HIV-1 infection, treatment: Oral:
Antiretroviral therapy-naive patients:
Note: Fosamprenavir is not recommended as a component of initial therapy for the treatment of HIV (HHS [adults] 2019).
Unboosted regimen: 1.4 g twice daily (without ritonavir).
Ritonavir-boosted regimens:
Once-daily regimen: Fosamprenavir 1.4 g once daily plus ritonavir 100 to 200 mg once daily.
Twice-daily regimen: Fosamprenavir 700 twice daily plus ritonavir 100 mg twice daily.
Protease inhibitor-experienced patients: Fosamprenavir 700 mg twice daily plus ritonavir 100 mg twice daily. Note: Once-daily administration is not recommended in protease inhibitor-experienced patients.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustments provided in the manufacturer's labeling (has not been studied); however, dosage adjustment unlikely due to minimal (eg, 1%) renal elimination of unchanged amprenavir.
Mild impairment (Child-Pugh class A): Reduce dosage of fosamprenavir to 700 mg twice daily without concurrent ritonavir (therapy naive) or fosamprenavir 700 mg twice daily plus ritonavir 100 mg once daily (therapy naive or PI experienced).
Moderate impairment (Child-Pugh class B): Reduce dosage of fosamprenavir to 700 mg twice daily without concurrent ritonavir (therapy naive) or fosamprenavir 450 mg twice daily plus ritonavir 100 mg once daily (therapy naive or PI experienced).
Severe impairment (Child-Pugh class C): Reduce dosage of fosamprenavir to 350 mg twice daily without concurrent ritonavir (therapy naive) or fosamprenavir 300 mg twice daily plus ritonavir 100 mg once daily (therapy naive or PI experienced).
(For additional information see "Fosamprenavir: Pediatric drug information")
Note: Gene mutation and antiretroviral (ARV) resistance patterns should be evaluated (refer to https://www.iasusa.org/ for more information) when necessary.
HIV-1 infection, treatment: Note: Although FDA approved, fosamprenavir is no longer recommended for use in pediatric patients due to low exposure levels (HHS [pediatric] 2019). If used, it should be in combination with other ARV agents. Do not administer fosamprenavir (with or without ritonavir) to protease inhibitor-experienced pediatric patients <6 months of age. In addition, once-daily dosing of fosamprenavir (with or without ritonavir) is not recommended in any pediatric patient (HHS [pediatric] 2018]).
Protease inhibitor-naive patients:
Ritonavir unboosted regimen: Children ≥2 years and Adolescents: Note: Manufacturer labeling may not reflect current practice. Oral: 30 mg/kg/dose twice daily; maximum dose 1,400 mg/dose.
Ritonavir-boosted regimen: Infants, Children, and Adolescents: Note: Manufacturer labeling may not reflect current practice. Per the manufacturer, use only in infants born at ≥38 weeks GA and who are at least 28 days PNA; however, experts recommend to avoid use in infants <6 months due to low systemic exposure (HHS [pediatric] 2018): Oral:
<11 kg: Fosamprenavir 45 mg/kg/dose plus ritonavir 7 mg/kg/dose twice daily.
11 to <15 kg: Fosamprenavir 30 mg/kg/dose plus ritonavir 3 mg/kg/dose twice daily.
15 to <20 kg: Fosamprenavir 23 mg/kg/dose plus ritonavir 3 mg/kg/dose twice daily.
≥20 kg: Fosamprenavir 18 mg/kg/dose (maximum dose: 700 mg/dose) twice daily plus ritonavir 3 mg/kg/dose (maximum dose: 100 mg/dose) twice daily.
Protease inhibitor-experienced: Ritonavir-boosted regimen: Note: Manufacturer labeling may not reflect current practice. Infants ≥6 months, Children, and Adolescents: Oral:
<11 kg: Fosamprenavir 45 mg/kg/dose plus ritonavir 7 mg/kg/dose twice daily.
11 to <15 kg: Fosamprenavir 30 mg/kg/dose plus ritonavir 3 mg/kg/dose twice daily.
15 to <20 kg: Fosamprenavir 23 mg/kg/dose plus ritonavir 3 mg/kg/dose twice daily.
≥20 kg: Fosamprenavir 18 mg/kg/dose (maximum dose: 700 mg/dose) twice daily plus ritonavir 3 mg/kg/dose twice daily (maximum dose: 100 mg/dose) twice daily.
Note: When combined with ritonavir, fosamprenavir tablets may be administered to children who weigh ≥39 kg.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Infants, Children, and Adolescents: No dosage adjustment necessary (HHS [pediatric] 2018).
There are no pediatric specific dosage adjustments provided in the manufacturer's labeling (has not been studied); based on experience in adult patients, dosing adjustment is suggested.
Refer to adult dosing.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Suspension, Oral, as calcium:
Lexiva: 50 mg/mL (225 mL) [contains methylparaben, polysorbate 80, propylene glycol, propylparaben; grape bubblegum peppermint flavor]
Tablet, Oral, as calcium:
Lexiva: 700 mg
Generic: 700 mg
May be product dependent
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Suspension, Oral, as calcium:
Telzir: 50 mg/mL (225 mL) [contains methylparaben, polysorbate 80, propylene glycol, propylparaben]
Tablet, Oral, as calcium:
Telzir: 700 mg
Oral suspension: Administer without food. Readminister dose of suspension if emesis occurs within 30 minutes after dosing. Shake suspension vigorously prior to use.
Tablet: Administer with food if taken with ritonavir. May be administered without regard to food if not taken with ritonavir.
Oral: Do not administer concurrently with antacids or buffered formulations of other medications (separate administration by 1 hour).
Oral suspension: Administer with food. Readminister dose of suspension if emesis occurs within 30 minutes after dosing. Shake suspension vigorously prior to use.
Tablets: Administer with food to pediatric patients.
HIV-1 infection, treatment: Treatment of HIV-1 infection, in combination with other antiretroviral agents. Note: Fosamprenavir is not recommended as a component of initial therapy for the treatment of HIV (HHS [adults] 2019).
Lexiva may be confused with Levitra, Pexeva
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
>10%:
Dermatologic: Skin rash (≤19%; onset: ~11 days; duration: ~13 days)
Endocrine & metabolic: Hypertriglyceridemia (>750 mg/dL: ≤11%)
Gastrointestinal: Diarrhea (5% to 13%; moderate-to-severe)
1% to 10%:
Central nervous system: Fatigue (2% to 4%; moderate-to-severe), headache (2% to 4%; moderate-to-severe)
Dermatologic: Pruritus (7% to 8%)
Endocrine & metabolic: Hyperglycemia (>251 mg/dL: ≤2%)
Gastrointestinal: Increased serum lipase (>2x ULN: 5% to 8%), nausea (3% to 7%; moderate-to-severe), vomiting (2% to 6%; moderate-to-severe), abdominal pain (≤2%; moderate-to-severe)
Hematologic & oncologic: Neutropenia (<750 cells/mm3: 3%)
Hepatic: Increased serum transaminases (>5x ULN: 4% to 8%)
<1%, postmarketing, and/or case reports: Angioedema, cerebrovascular accident, hypercholesterolemia, myocardial infarction, nephrolithiasis, oral paresthesia, Stevens-Johnson syndrome
Clinically significant hypersensitivity (eg, Stevens-Johnson syndrome) to fosamprenavir, amprenavir, or any component of the formulation; coadministration with drugs highly dependent on CYP3A4 for clearance and for which elevated plasma concentrations are associated with serious and/or life-threatening events (eg, alfuzosin, rifampin, ergot derivatives [eg, dihydroergotamine, ergonovine, ergotamine, methylergonovine], cisapride, St. John's wort, lovastatin, lomitapide, simvastatin, pimozide, delavirdine, sildenafil [when used for treatment of pulmonary arterial hypertension], midazolam, or triazolam); use of flecainide, lurasidone, or propafenone with concomitant ritonavir therapy.
Also refer to the ritonavir monograph, if used in combination with ritonavir, for additional contraindications.
Canadian labeling: Additional contraindications (not in US labeling): Coadministration with antihistamines, GI motility agents, amiodarone, diazepam, flurazepam, lidocaine (systemic), quetiapine.
Concerns related to adverse effects:
• Body fat increase: May cause an increase in body fat.
• Hemolytic anemia: Acute hemolytic anemia has been reported in association with amprenavir use.
• Hepatic effects: May cause transaminase elevations, hepatitis, and/or exacerbate preexisting hepatic dysfunction; use with caution in patients with underlying hepatic disease, such as hepatitis B or C or cirrhosis.
• Hypersensitivity reactions: Protease inhibitors have been associated with a variety of hypersensitivity events (some severe), including rash, anaphylaxis (rare), angioedema, bronchospasm, erythema multiforme, and/or Stevens-Johnson syndrome (rare). It is generally recommended to discontinue treatment if severe rash or moderate symptoms accompanied by other systemic symptoms occur.
• Immune reconstitution syndrome: Patients may develop immune reconstitution syndrome resulting in the occurrence of an inflammatory response to an indolent or residual opportunistic infection during initial HIV treatment or activation of autoimmune disorders (eg, Graves disease, polymyositis, Guillain-Barré syndrome) later in therapy; further evaluation and treatment may be required.
• Lipid elevations: Increases in total cholesterol and triglycerides have been reported; screening should be done prior to therapy and periodically throughout treatment.
• Nephrolithiasis: Cases have been reported in postmarketing surveillance; temporary or permanent discontinuation of therapy should be considered if symptoms develop.
• Sulfonamide allergy: Use with caution in patients with sulfonamide allergy. In clinical trials, the incidence of rash did not differ appreciably in patients with or without a history of sulfonamide allergy.
Disease-related concerns:
• Diabetes: Changes in glucose tolerance, hyperglycemia, exacerbation of diabetes, diabetic ketoacidosis, and new-onset diabetes mellitus have been reported in patients receiving protease inhibitors.
• Hemophilia A or B: Use with caution in patients with hemophilia A or B; increased bleeding during protease inhibitor therapy has been reported.
• Hepatic impairment: Use with caution; dosage adjustment required.
Special populations:
• Protease inhibitor-experienced adults: Once-daily fosamprenavir/ritonavir is not recommended in protease inhibitor-experienced adults.
Dosage forms specific issues:
• Polysorbate 80: Some dosage forms may contain polysorbate 80 (also known as Tweens). Hypersensitivity reactions, usually a delayed reaction, have been reported following exposure to pharmaceutical products containing polysorbate 80 in certain individuals (Isaksson 2002; Lucente 2000; Shelley 1995). Thrombocytopenia, ascites, pulmonary deterioration, and renal and hepatic failure have been reported in premature neonates after receiving parenteral products containing polysorbate 80 (Alade 1986; CDC 1984).
• Propylene glycol: Some dosage forms may contain propylene glycol; large amounts are potentially toxic and have been associated with hyperosmolality, lactic acidosis, seizures, and respiratory depression; use caution (AAP 1997; Zar 2007).
Some dosage forms may contain propylene glycol; in neonates, large amounts of propylene glycol delivered orally, intravenously (eg, >3,000 mg/day), or topically have been associated with potentially fatal toxicities which can include metabolic acidosis, seizures, renal failure, and CNS depression; toxicities have also been reported in children and adults including hyperosmolality, lactic acidosis, seizures, and respiratory depression; use caution (AAP 1997; Shehab 2009).
Substrate of CYP2C9 (minor), CYP2D6 (minor), CYP3A4 (major), P-glycoprotein/ABCB1 (minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential; Inhibits CYP3A4 (moderate)
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the Lexicomp drug interactions program by clicking on the “Launch drug interactions program” link above.
Abemaciclib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Abemaciclib. Management: Monitor for increased abemaciclib toxicities if combined with moderate CYP3A4 inhibitors. Consider reducing the abemaciclib dose in 50 mg decrements if necessary. Risk C: Monitor therapy
Acalabrutinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Acalabrutinib. Management: Reduce acalabrutinib dose to 100 mg once daily with concurrent use of a moderate CYP3A4 inhibitor. Monitor patient closely for both acalabrutinib response and evidence of adverse effects with any concurrent use. Risk D: Consider therapy modification
Adagrasib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Adagrasib. Risk C: Monitor therapy
Alfentanil: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Alfentanil. Management: If use of alfentanil and moderate CYP3A4 inhibitors is necessary, consider dosage reduction of alfentanil until stable drug effects are achieved. Frequently monitor patients for respiratory depression and sedation when these agents are combined. Risk D: Consider therapy modification
Alfuzosin: Fosamprenavir may increase the serum concentration of Alfuzosin. Risk X: Avoid combination
Alitretinoin (Systemic): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Alitretinoin (Systemic). Risk C: Monitor therapy
ALPRAZolam: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of ALPRAZolam. Management: Consider alternatives to this combination when possible. If combined, consider an alprazolam dose reduction and monitor for increased alprazolam effects and toxicities (eg, sedation, lethargy). Risk D: Consider therapy modification
Amiodarone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Amiodarone. Risk C: Monitor therapy
AmLODIPine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of AmLODIPine. Risk C: Monitor therapy
Antidiabetic Agents: Hyperglycemia-Associated Agents may diminish the therapeutic effect of Antidiabetic Agents. Risk C: Monitor therapy
Apixaban: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Apixaban. Risk C: Monitor therapy
Aprepitant: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Aprepitant. Risk X: Avoid combination
ARIPiprazole: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of ARIPiprazole. Management: Monitor for increased aripiprazole pharmacologic effects. Aripiprazole dose adjustments may or may not be required based on concomitant therapy, indication, or dosage form. Consult full interaction monograph for specific recommendations. Risk C: Monitor therapy
ARIPiprazole Lauroxil: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of ARIPiprazole Lauroxil. Risk C: Monitor therapy
Artemether and Lumefantrine: Protease Inhibitors may increase the serum concentration of Artemether and Lumefantrine. Specifically, the concentrations of lumefantrine may be increased. Protease Inhibitors may decrease the serum concentration of Artemether and Lumefantrine. Specifically, concentrations of artemether and dihydroartemisinin (DHA), the active metabolite of artemether, may be decreased. Risk C: Monitor therapy
Astemizole: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Astemizole. Management: Avoid concomitant use of astemizole and moderate CYP3A4 inhibitors whenever possible. If combined, monitor closely for increased astemizole toxicities, especially for QTc interval prolongation. Risk D: Consider therapy modification
Asunaprevir: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Asunaprevir. Risk X: Avoid combination
Atazanavir: May increase serum concentrations of the active metabolite(s) of Fosamprenavir. Fosamprenavir may decrease the serum concentration of Atazanavir. Management: Consider alternatives to this combination. Safe and effective doses of fosamprenavir and atazanavir have not been established for concurrent use. Risk D: Consider therapy modification
Atogepant: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Atogepant. Risk C: Monitor therapy
Atorvastatin: May increase serum concentrations of the active metabolite(s) of Fosamprenavir. Fosamprenavir may increase the serum concentration of Atorvastatin. Management: Use the lowest atorvastatin dose necessary and limit the atorvastatin dose to 20 mg daily in patients taking fosamprenavir. Monitor patients for signs and symptoms of myopathy at initiation of therapy and with any dose increase. Risk D: Consider therapy modification
Avacopan: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Avacopan. Risk C: Monitor therapy
Avanafil: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Avanafil. Management: The maximum avanafil dose is 50 mg per 24-hour period when used together with a moderate CYP3A4 inhibitor. Patients receiving such a combination should also be monitored more closely for evidence of adverse effects (eg, hypotension, syncope, priapism). Risk D: Consider therapy modification
Avapritinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Avapritinib. Management: Avoid use of moderate CYP3A4 inhibitors with avapritinib. If this combination cannot be avoided, reduce the avapritinib dose to 100 mg daily for the treatment of GIST or to 50 mg daily for the treatment of advanced systemic mastocytosis. Risk D: Consider therapy modification
Axitinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Axitinib. Risk C: Monitor therapy
Barnidipine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Barnidipine. Risk C: Monitor therapy
Bedaquiline: CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Bedaquiline. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Bedaquiline. Risk C: Monitor therapy
Benidipine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Benidipine. Risk C: Monitor therapy
Benzhydrocodone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Benzhydrocodone. Specifically, the concentration of hydrocodone may be increased. Risk C: Monitor therapy
Betibeglogene Autotemcel: Antiretroviral Agents may diminish the therapeutic effect of Betibeglogene Autotemcel. Risk X: Avoid combination
Blonanserin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Blonanserin. Risk C: Monitor therapy
Bortezomib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Bortezomib. Risk C: Monitor therapy
Bosentan: Protease Inhibitors may increase the serum concentration of Bosentan. Management: Dose adjustment of bosentan and increased monitoring for bosentan toxicities is necessary when these agents are combined. See full drug interaction monograph for details. Risk D: Consider therapy modification
Bosutinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Bosutinib. Risk X: Avoid combination
Brexpiprazole: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Brexpiprazole. Management: The brexpiprazole dose should be reduced to 25% of usual if used together with both a moderate CYP3A4 inhibitor and a strong or moderate CYP2D6 inhibitor, or if a moderate CYP3A4 inhibitor is used in a CYP2D6 poor metabolizer. Risk C: Monitor therapy
Brigatinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Brigatinib. Management: Avoid concurrent use of brigatinib with moderate CYP3A4 inhibitors when possible. If such a combination cannot be avoided, reduce the dose of brigatinib by approximately 40% (ie, from 180 mg to 120 mg, from 120 mg to 90 mg, or from 90 mg to 60 mg). Risk D: Consider therapy modification
Bromocriptine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Bromocriptine. Management: The bromocriptine dose should not exceed 1.6 mg daily with use of a moderate CYP3A4 inhibitor. The Cycloset brand specifically recommends this dose limitation, but other bromocriptine products do not make such specific recommendations. Risk D: Consider therapy modification
Budesonide (Oral Inhalation): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Budesonide (Oral Inhalation). Risk C: Monitor therapy
Budesonide (Systemic): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Budesonide (Systemic). Management: Avoid the concomitant use of CYP3A4 inhibitors and oral budesonide. If patients receive both budesonide and CYP3A4 inhibitors, they should be closely monitored for signs and symptoms of corticosteroid excess. Risk D: Consider therapy modification
Budesonide (Topical): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Budesonide (Topical). Risk X: Avoid combination
Buprenorphine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Buprenorphine. Risk C: Monitor therapy
BusPIRone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of BusPIRone. Risk C: Monitor therapy
Cabozantinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cabozantinib. Risk C: Monitor therapy
Cannabis: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cannabis. More specifically, tetrahydrocannabinol and cannabidiol serum concentrations may be increased. Risk C: Monitor therapy
CarBAMazepine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of CarBAMazepine. Risk C: Monitor therapy
Cariprazine: CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Cariprazine. Specifically, concentrations of didesmethylcariprazine (DDCAR), the primary active metabolite of cariprazine, may increase. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cariprazine. Risk C: Monitor therapy
Ceritinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ceritinib. Risk C: Monitor therapy
Cilostazol: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cilostazol. Management: Decrease the dose of cilostazol to 50 mg twice daily when combined with moderate CYP3A4 inhibitors. Risk D: Consider therapy modification
Cisapride: Fosamprenavir may increase the serum concentration of Cisapride. Risk X: Avoid combination
Clarithromycin: Protease Inhibitors may decrease serum concentrations of the active metabolite(s) of Clarithromycin. Protease Inhibitors may increase the serum concentration of Clarithromycin. Management: Do not exceed clarithromycin doses greater than 1,000 mg/day in patients taking protease inhibitors. If CrCL is 30 to 60 mL/min, reduced clarithromycin dose 50%. If CrCL is less than 30 mL/min, reduced clarithromycin dose 75%. Risk D: Consider therapy modification
Clindamycin (Systemic): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Clindamycin (Systemic). Risk C: Monitor therapy
Clofazimine: May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Risk C: Monitor therapy
Clorazepate: Fosamprenavir may increase the serum concentration of Clorazepate. Risk C: Monitor therapy
CloZAPine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of CloZAPine. Risk C: Monitor therapy
Cobicistat: May increase the serum concentration of Fosamprenavir. However, the magnitude of this change is unclear, and dosing recommendations for this combination are not available. Risk X: Avoid combination
Cobimetinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Cobimetinib. Management: Avoid this combination when possible. If concurrent short term (14 days or less) use cannot be avoided, reduce the cobimetinib dose from 60 mg to 20 mg daily. Avoid concomitant use in patients already receiving reduced cobimetinib doses. Risk D: Consider therapy modification
Codeine: CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Codeine. Risk C: Monitor therapy
Colchicine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Colchicine. Management: Reduce colchicine dose as directed when using with a moderate CYP3A4 inhibitor, and increase monitoring for colchicine-related toxicity. See interaction monograph for details. Use extra caution in patients with impaired renal and/or hepatic function. Risk D: Consider therapy modification
Conivaptan: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Conivaptan. Risk C: Monitor therapy
Copanlisib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Copanlisib. Risk C: Monitor therapy
Crizotinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Crizotinib. Risk C: Monitor therapy
Cyclophosphamide: Protease Inhibitors may enhance the adverse/toxic effect of Cyclophosphamide. Specifically, the incidences of neutropenia, infection, and mucositis may be increased. Protease Inhibitors may increase the serum concentration of Cyclophosphamide. Risk C: Monitor therapy
CycloSPORINE (Systemic): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of CycloSPORINE (Systemic). Risk C: Monitor therapy
CYP3A4 Inducers (Moderate): May decrease serum concentrations of the active metabolite(s) of Fosamprenavir. Risk C: Monitor therapy
CYP3A4 Inducers (Strong): May decrease serum concentrations of the active metabolite(s) of Fosamprenavir. Risk C: Monitor therapy
CYP3A4 Inhibitors (Moderate): May increase the serum concentration of Fosamprenavir. Risk C: Monitor therapy
CYP3A4 Inhibitors (Strong): May increase the serum concentration of Fosamprenavir. Risk C: Monitor therapy
Dabrafenib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Dabrafenib. Risk C: Monitor therapy
Dapoxetine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Dapoxetine. Management: The dose of dapoxetine should be limited to 30 mg per day when used together with a moderate inhibitor of CYP3A4. Risk D: Consider therapy modification
Daridorexant: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Daridorexant. Management: Limit the daridorexant dose to 25 mg, no more than once per night, when combined with moderate CYP3A4 inhibitors. Risk D: Consider therapy modification
Darifenacin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Darifenacin. Risk C: Monitor therapy
Darunavir: Protease Inhibitors may decrease the serum concentration of Darunavir. Protease Inhibitors may increase the serum concentration of Darunavir. Risk X: Avoid combination
Dasatinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Dasatinib. Risk C: Monitor therapy
Deflazacort: CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Deflazacort. Management: Administer one third of the recommended deflazacort dose when used together with a strong or moderate CYP3A4 inhibitor. Risk D: Consider therapy modification
Delamanid: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Delamanid. Risk C: Monitor therapy
Delavirdine: Fosamprenavir may decrease the serum concentration of Delavirdine. The active metabolite amprenavir is likely responsible for this effect. Delavirdine may increase the serum concentration of Fosamprenavir. Specifically, delavirdine may increase concentrations of the active metabolite amprenavir. Risk X: Avoid combination
DexAMETHasone (Systemic): May decrease the serum concentration of Fosamprenavir. Fosamprenavir may increase the serum concentration of DexAMETHasone (Systemic). Risk C: Monitor therapy
DiazePAM: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of DiazePAM. Risk C: Monitor therapy
DilTIAZem: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of DilTIAZem. Risk C: Monitor therapy
Disopyramide: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Disopyramide. Risk C: Monitor therapy
DOCEtaxel: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of DOCEtaxel. Risk C: Monitor therapy
Dofetilide: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Dofetilide. Risk C: Monitor therapy
Dolutegravir: Fosamprenavir may decrease the serum concentration of Dolutegravir. Specifically, Fosamprenavir/Ritonavir may decrease the serum concentration of Dolutegravir. The individual contributions of Fosamprenavir and Ritonavir to this effect are unknown. Management: Increase dolutegravir to 50 mg twice/day in adults. Increase weight-based dose to twice daily in pediatric patients. Recommendations vary for combo products; see interaction monograph for details. Not recommended with Dovato or Juluca brand combos. Risk D: Consider therapy modification
Domperidone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Domperidone. Risk X: Avoid combination
DOXOrubicin (Conventional): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of DOXOrubicin (Conventional). Risk X: Avoid combination
Dronabinol: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Dronabinol. Risk C: Monitor therapy
Dronedarone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Dronedarone. Risk C: Monitor therapy
Ebastine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ebastine. Risk C: Monitor therapy
Efavirenz: May decrease serum concentrations of the active metabolite(s) of Fosamprenavir. Management: For once-daily fosamprenavir/ritonavir with efavirenz, increase ritonavir dose to 300 mg/day in adult patients. No ritonavir dose adjustment is required if using twice-daily fosamprenavir/ritonavir. Risk D: Consider therapy modification
Elbasvir and Grazoprevir: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Elbasvir and Grazoprevir. Risk C: Monitor therapy
Eletriptan: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Eletriptan. Risk X: Avoid combination
Elexacaftor, Tezacaftor, and Ivacaftor: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Elexacaftor, Tezacaftor, and Ivacaftor. Management: When combined with moderate CYP3A4 inhibitors, two elexacaftor/tezacaftor/ivacaftor (100 mg/50 mg/75 mg) tablets should be given in the morning, every other day. Ivacaftor (150 mg) should be given in the morning, every other day on alternate days. Risk D: Consider therapy modification
Eliglustat: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Eliglustat. Management: Reduce eliglustat dose to 84 mg daily in CYP2D6 EMs when used with moderate CYP3A4 inhibitors. Avoid use of moderate CYP3A4 inhibitors in CYP2D6 IMs or PMs. Use in CYP2D6 EMs or IMs also taking strong or moderate CYP2D6 inhibitors is contraindicated. Risk D: Consider therapy modification
Elivaldogene Autotemcel: Antiretroviral Agents may diminish the therapeutic effect of Elivaldogene Autotemcel. Management: Avoid use of antiretroviral medications for at least one month, or for the amount of time required for elimination of the retroviral medication, prior to stem cell mobilization and until the all apheresis cycles are finished Risk X: Avoid combination
Encorafenib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Encorafenib. Management: Avoid use of encorafenib and moderate CYP3A4 inhibitors when possible. If combined, decrease the encorafenib dose from 450 mg to 225 mg; 300 mg to 150 mg; and 225 mg or 150 mg to 75 mg. Resume prior dose once inhibitor discontinued for 3 to 5 half-lives. Risk D: Consider therapy modification
Entrectinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Entrectinib. Management: Avoid moderate CYP3A4 inhibitors during treatment with entrectinib. Reduce dose to 200 mg/day if combination cannot be avoided in adults and those 12 yrs of age or older with a BSA of at least 1.5 square meters. Avoid if BSA is less than 1.5 square meters Risk D: Consider therapy modification
Eplerenone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Eplerenone. Management: If coadministered with moderate CYP3A4 inhibitors, the max dose of eplerenone is 25 mg daily if used for heart failure; if used for hypertension initiate eplerenone 25 mg daily, titrate to max 25 mg twice daily. Risk D: Consider therapy modification
Ergot Derivatives (Vasoconstrictive CYP3A4 Substrates): Fosamprenavir may increase the serum concentration of Ergot Derivatives (Vasoconstrictive CYP3A4 Substrates). Risk X: Avoid combination
Erlotinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Erlotinib. Risk C: Monitor therapy
Erythromycin (Systemic): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Erythromycin (Systemic). Risk C: Monitor therapy
Estrogen Derivatives: Protease Inhibitors may decrease the serum concentration of Estrogen Derivatives. Protease Inhibitors may increase the serum concentration of Estrogen Derivatives. Risk C: Monitor therapy
Eszopiclone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Eszopiclone. Risk C: Monitor therapy
Etravirine: May increase serum concentrations of the active metabolite(s) of Fosamprenavir. Specifically, amprenavir concentrations may increase. Risk X: Avoid combination
Everolimus: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Everolimus. Risk C: Monitor therapy
Fedratinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Fedratinib. Risk C: Monitor therapy
Felodipine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Felodipine. Risk C: Monitor therapy
FentaNYL: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of FentaNYL. Management: Consider fentanyl dose reductions when combined with a moderate CYP3A4 inhibitor. Monitor for respiratory depression and sedation. Upon discontinuation of a CYP3A4 inhibitor, consider a fentanyl dose increase; monitor for signs and symptoms of withdrawal. Risk D: Consider therapy modification
Fexinidazole: May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Risk X: Avoid combination
Finerenone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Finerenone. Risk C: Monitor therapy
Flibanserin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Flibanserin. Management: Use of flibanserin with moderate CYP3A4 inhibitors is contraindicated. If starting flibanserin, start 2 weeks after the last dose of the CYP3A4 inhibitor. If starting a CYP3A4 inhibitor, start 2 days after the last dose of flibanserin. Risk X: Avoid combination
Flurazepam: Fosamprenavir may increase the serum concentration of Flurazepam. Risk C: Monitor therapy
Fluticasone (Nasal): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Fluticasone (Nasal). Risk C: Monitor therapy
Fluticasone (Oral Inhalation): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Fluticasone (Oral Inhalation). Risk C: Monitor therapy
Fosaprepitant: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Fosaprepitant. Risk X: Avoid combination
Fosphenytoin: May decrease the serum concentration of Fosamprenavir. Fosamprenavir may decrease the serum concentration of Fosphenytoin. Specifically, fosamprenavir boosted with ritonavir may decrease phenytoin concentrations. Risk C: Monitor therapy
Fusidic Acid (Systemic): May increase the serum concentration of CYP3A4 Substrates (High risk with Inhibitors). Risk X: Avoid combination
Garlic: May decrease the serum concentration of Protease Inhibitors. Risk X: Avoid combination
Gilteritinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Gilteritinib. Risk C: Monitor therapy
Glasdegib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Glasdegib. Risk C: Monitor therapy
GuanFACINE: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of GuanFACINE. Management: Reduce the extended-release guanfacine dose 50% when combined with a moderate CYP3A4 inhibitor. Monitor for increased guanfacine toxicities when these agents are combined. Risk D: Consider therapy modification
Halofantrine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Halofantrine. Risk C: Monitor therapy
Histamine H2 Receptor Antagonists: May decrease the serum concentration of Fosamprenavir. Cimetidine may also inhibit the metabolism of the active metabolite amprenavir, making its effects on fosamprenavir/amprenavir concentrations difficult to predict. Risk C: Monitor therapy
Hormonal Contraceptives: Protease Inhibitors may decrease the serum concentration of Hormonal Contraceptives. Specifically, protease inhibitors may decrease concentrations of estrogens. Protease Inhibitors may increase the serum concentration of Hormonal Contraceptives. Specifically, protease inhibitors may increase concentrations of progestins. Management: Use alternative or additional nonhormonal forms of contraception when estrogen-containing hormonal contraceptives are combined with protease inhibitors. Progestin-only contraceptives can be used without back up, but monitor for progestin toxicities. Risk D: Consider therapy modification
HYDROcodone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of HYDROcodone. Risk C: Monitor therapy
Ibrutinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ibrutinib. Management: When treating B-cell malignancies, decrease ibrutinib to 280 mg daily when combined with moderate CYP3A4 inhibitors. When treating graft versus host disease, monitor patients closely and reduce the ibrutinib dose as needed based on adverse reactions. Risk D: Consider therapy modification
Ifosfamide: CYP3A4 Inhibitors (Moderate) may decrease serum concentrations of the active metabolite(s) of Ifosfamide. Risk C: Monitor therapy
Iloperidone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Iloperidone. Risk C: Monitor therapy
Indinavir: May increase serum concentrations of the active metabolite(s) of Fosamprenavir. Management: Consider alternatives to this combination. Safe and effective doses of fosamprenavir and indinavir during coadministration have not been established. Risk D: Consider therapy modification
Infigratinib: CYP3A4 Inhibitors (Moderate) may decrease serum concentrations of the active metabolite(s) of Infigratinib. CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Infigratinib. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Infigratinib. Risk X: Avoid combination
Irinotecan Products: CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Irinotecan Products. Specifically, the serum concentration of SN-38 may be increased. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Irinotecan Products. Risk C: Monitor therapy
Isavuconazonium Sulfate: CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Isavuconazonium Sulfate. Specifically, CYP3A4 Inhibitors (Moderate) may increase isavuconazole serum concentrations. Risk C: Monitor therapy
Isradipine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Isradipine. Risk C: Monitor therapy
Itraconazole: May increase serum concentrations of the active metabolite(s) of Fosamprenavir. Specifically, amprenavir concentrations may be increased. Fosamprenavir may increase the serum concentration of Itraconazole. Management: Limit the adult maximum itraconazole dose to 200 mg/day with fosamprenavir/ritonavir. In patients receiving fosamprenavir without ritonavir, patients receiving greater than 400 mg/day itraconazole may also require dose reduction. Risk D: Consider therapy modification
Ivabradine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ivabradine. Risk X: Avoid combination
Ivacaftor: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ivacaftor. Management: Ivacaftor dose reductions may be required; consult full drug interaction monograph content for age- and weight-specific dosage recommendations. Risk D: Consider therapy modification
Ivosidenib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ivosidenib. Management: Avoid use of moderate CYP3A4 inhibitors with ivosidenib whenever possible. If combined, monitor for increased ivosidenib toxicities, including QTc prolongation. Risk D: Consider therapy modification
Ixabepilone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ixabepilone. Risk C: Monitor therapy
Ketoconazole (Systemic): May increase serum concentrations of the active metabolite(s) of Fosamprenavir. Specifically, amprenavir concentrations may be increased. Fosamprenavir may increase the serum concentration of Ketoconazole (Systemic). Management: Limit the adult maximum ketoconazole dose to 200 mg/day with fosamprenavir/ritonavir. In patients receiving fosamprenavir without ritonavir, patients receiving greater than 400 mg/day ketoconazole may also require dose reduction. Risk D: Consider therapy modification
Lapatinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lapatinib. Risk C: Monitor therapy
Larotrectinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Larotrectinib. Risk C: Monitor therapy
Lefamulin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lefamulin. Management: Monitor for lefamulin adverse effects during coadministration of lefamulin tablets with moderate CYP3A4 inhibitors. Risk C: Monitor therapy
Lemborexant: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lemborexant. Risk X: Avoid combination
Lercanidipine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lercanidipine. Risk C: Monitor therapy
Levamlodipine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Levamlodipine. Risk C: Monitor therapy
Levoketoconazole: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Levoketoconazole. Risk C: Monitor therapy
Levomethadone: Fosamprenavir may decrease the serum concentration of Levomethadone. Risk C: Monitor therapy
Levomilnacipran: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Levomilnacipran. Risk C: Monitor therapy
Lidocaine (Systemic): CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Lidocaine (Systemic). Specifically, concentrations of monoethylglycinexylidide (MEGX) may be increased. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lidocaine (Systemic). Risk C: Monitor therapy
Lomitapide: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lomitapide. Risk X: Avoid combination
Lonafarnib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lonafarnib. Risk X: Avoid combination
Lopinavir: Fosamprenavir may decrease the serum concentration of Lopinavir. Specifically, amprenavir (the active metabolite of fosamprenavir) may decrease the serum concentration of lopinavir. Lopinavir may decrease the serum concentration of Fosamprenavir. Specifically, lopinavir/ritonavir may decrease the serum concentration of amprenavir (the active metabolite of fosamprenavir) Risk X: Avoid combination
Lovastatin: Fosamprenavir may increase the serum concentration of Lovastatin. Risk X: Avoid combination
Lumateperone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lumateperone. Management: Limit the lumateperone dose to 21 mg once daily when used with a moderate CYP3A4 inhibitor. Risk D: Consider therapy modification
Lurasidone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lurasidone. Management: US labeling recommends reducing lurasidone dose by 50% with a moderate CYP3A4 inhibitor and initiating 20 mg/day, max 80 mg/day. Some non-US labels recommend initiating lurasidone 20 mg/day, max 40 mg/day. Avoid concurrent use of grapefruit products. Risk D: Consider therapy modification
Lurbinectedin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Lurbinectedin. Management: Avoid concomitant use of lurbinectedin and moderate CYP3A4 inhibitors when possible. If combined, consider a lurbinectedin dose reduction as clinically indicated. Risk D: Consider therapy modification
Macitentan: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Macitentan. Risk C: Monitor therapy
Manidipine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Manidipine. Risk C: Monitor therapy
Maraviroc: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Maraviroc. Risk C: Monitor therapy
Mavacamten: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Mavacamten. Management: Start mavacamten at 5 mg/day if stable on a moderate CYP3A4 inhibitor. For those stable on mavacamten who are initiating a moderate CYP3A4 inhibitor, reduce mavacamten dose by one dose level. Risk D: Consider therapy modification
Meperidine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Meperidine. Risk C: Monitor therapy
Methadone: Fosamprenavir may decrease the serum concentration of Methadone. Risk C: Monitor therapy
MethylPREDNISolone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of MethylPREDNISolone. Risk C: Monitor therapy
Methysergide: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Methysergide. Risk X: Avoid combination
Midazolam: Protease Inhibitors may increase the serum concentration of Midazolam. Management: Oral midazolam is contraindicated with protease inhibitors. Avoid use with nasal midazolam. Consider alternatives to use with other routes of midazolam (IV, IM) when possible. Consider use of lower midazolam doses if combined. Risk X: Avoid combination
Midostaurin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Midostaurin. Risk C: Monitor therapy
MiFEPRIStone: Fosamprenavir may increase the serum concentration of MiFEPRIStone. Management: For treatment of hyperglycemia in Cushing's syndrome, start mifepristone at 300 mg/day, may titrate to a maximum of 900 mg/day. If starting fosamprenavir and taking > 300 mg/day mifepristone, decrease the mifepristone dose by 300 mg/day. Risk D: Consider therapy modification
Mirodenafil: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Mirodenafil. Risk C: Monitor therapy
Mitapivat: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Mitapivat. Management: When coadministered with moderate CYP3A4 inhibitors, doses of mitapivat should not exceed 20 mg twice daily. Additionally, patients should be monitored for changes in hemoglobin response and increased mitapivat adverse effects. Risk D: Consider therapy modification
Mobocertinib: CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Mobocertinib. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Mobocertinib. Management: Avoid use of moderate CYP3A4 inhibitors with mobocertinib when possible. If combined, the mobocertinib dose should be reduced by approximately 50% (ie, from 160 mg to 80 mg, 120 mg to 40 mg, or 80 mg to 40 mg). Monitor QTc interval closely. Risk D: Consider therapy modification
Naldemedine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Naldemedine. Risk C: Monitor therapy
Nalfurafine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Nalfurafine. Risk C: Monitor therapy
Naloxegol: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Naloxegol. Management: The use of naloxegol and moderate CYP3A4 inhibitors should be avoided. If concurrent use is unavoidable, reduce naloxegol dose to 12.5 mg once daily and monitor for signs of opiate withdrawal (eg, hyperhidrosis, chills, diarrhea, anxiety, irritability). Risk D: Consider therapy modification
Nelfinavir: May increase serum concentrations of the active metabolite(s) of Fosamprenavir. Management: Consider alternatives to this combination. Safe and effective doses of fosamprenavir and nelfinavir during coadministration have not been established. Risk D: Consider therapy modification
Neratinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Neratinib. Risk C: Monitor therapy
Nevirapine: May decrease serum concentrations of the active metabolite(s) of Fosamprenavir. Fosamprenavir may increase the serum concentration of Nevirapine. Management: Coadministration of nevirapine and fosamprenavir is not recommended without concurrent ritonavir. However, when nevirapine and fosamprenavir/ritonavir (twice daily) are used in combination, no dose adjustment is required. Risk D: Consider therapy modification
NIFEdipine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of NIFEdipine. Risk C: Monitor therapy
Nilotinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Nilotinib. Risk C: Monitor therapy
NiMODipine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of NiMODipine. Risk C: Monitor therapy
Nisoldipine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Nisoldipine. Risk X: Avoid combination
Nitrendipine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Nitrendipine. Risk C: Monitor therapy
Olaparib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Olaparib. Management: Avoid use of moderate CYP3A4 inhibitors with olaparib, if possible. If such concurrent use cannot be avoided, the dose of olaparib tablets should be reduced to 150 mg twice daily and the dose of olaparib capsules should be reduced to 200 mg twice daily. Risk D: Consider therapy modification
Oliceridine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Oliceridine. Risk C: Monitor therapy
Olmutinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Olmutinib. Risk C: Monitor therapy
Ombitasvir, Paritaprevir, Ritonavir, and Dasabuvir: May increase serum concentrations of the active metabolite(s) of Fosamprenavir. Fosamprenavir may increase the serum concentration of Ombitasvir, Paritaprevir, Ritonavir, and Dasabuvir. Management: Use of ritonavir-boosted fosamprenavir with ombitasvir/paritaprevir/ritonavir/dasabuvir is not recommended. Consider a reduced dose of fosamprenavir 1400 mg once daily (unboosted) when used with ombitasvir/paritaprevir/ritonavir/dasabuvir. Risk D: Consider therapy modification
Orelabrutinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Orelabrutinib. Risk X: Avoid combination
Orlistat: May decrease the serum concentration of Antiretroviral Agents. Risk C: Monitor therapy
OxyCODONE: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of OxyCODONE. Serum concentrations of the active metabolite Oxymorphone may also be increased. Risk C: Monitor therapy
PACLitaxel (Conventional): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of PACLitaxel (Conventional). Risk C: Monitor therapy
PACLitaxel (Protein Bound): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of PACLitaxel (Protein Bound). Risk C: Monitor therapy
Pacritinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Pacritinib. Risk X: Avoid combination
Palbociclib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Palbociclib. Risk C: Monitor therapy
Palovarotene: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Palovarotene. Risk C: Monitor therapy
Panobinostat: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Panobinostat. Risk C: Monitor therapy
PARoxetine: Fosamprenavir may decrease the serum concentration of PARoxetine. The active metabolite amprenavir is likely responsible for this effect. Risk C: Monitor therapy
PAZOPanib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of PAZOPanib. Risk C: Monitor therapy
Pemigatinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Pemigatinib. Management: If combined use cannot be avoided, reduce the pemigatinib dose from 13.5 mg daily to 9 mg daily, or from 9 mg daily to 4.5 mg daily. Resume prior pemigatinib dose after stopping the moderate inhibitor once 3 half-lives of the inhibitor has passed. Risk D: Consider therapy modification
Pexidartinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Pexidartinib. Management: Avoid use of pexidartinib with moderate CYP3A4 inhibitors if possible. If combined, the pexidartinib dose should be reduced. Decrease 800 mg or 600 mg daily doses to 200 mg twice daily. Decrease doses of 400 mg per day to 200 mg once daily. Risk D: Consider therapy modification
Phenytoin: Fosamprenavir may decrease the serum concentration of Phenytoin. Specifically, fosamprenavir boosted with ritonavir may decrease phenytoin concentrations. Phenytoin may decrease the serum concentration of Fosamprenavir. Specifically, phenytoin may decrease the concentration of the active metabolite amprenavir. Risk C: Monitor therapy
Pimavanserin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Pimavanserin. Risk C: Monitor therapy
Pimecrolimus: CYP3A4 Inhibitors (Moderate) may decrease the metabolism of Pimecrolimus. Risk C: Monitor therapy
Pimozide: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Pimozide. Risk X: Avoid combination
Piperaquine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Piperaquine. Risk C: Monitor therapy
PONATinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of PONATinib. Risk C: Monitor therapy
Posaconazole: May decrease serum concentrations of the active metabolite(s) of Fosamprenavir. Fosamprenavir may decrease the serum concentration of Posaconazole. Risk C: Monitor therapy
Prazepam: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Prazepam. Risk C: Monitor therapy
Praziquantel: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Praziquantel. Risk C: Monitor therapy
Propafenone: Fosamprenavir may increase the serum concentration of Propafenone. Management: Concurrent use of ritonavir-boosted fosamprenavir with propafenone is contraindicated. The use of non-ritonavir-boosted fosamprenavir with propafenone is not specifically contraindicated but should only be undertaken with caution. Risk X: Avoid combination
QUEtiapine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of QUEtiapine. Risk C: Monitor therapy
QuiNIDine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of QuiNIDine. Risk C: Monitor therapy
Quinidine (Non-Therapeutic): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Quinidine (Non-Therapeutic). Risk C: Monitor therapy
QuiNINE: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of QuiNINE. Risk C: Monitor therapy
Raltegravir: Fosamprenavir may decrease the serum concentration of Raltegravir. Raltegravir may decrease the serum concentration of Fosamprenavir. Risk X: Avoid combination
Ranolazine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ranolazine. Management: Limit the ranolazine dose to a maximum of 500 mg twice daily in patients concurrently receiving moderate CYP3A4 inhibitors. Monitor for increased ranolazine effects and toxicities during concomitant use. Risk D: Consider therapy modification
Red Yeast Rice: Fosamprenavir may increase the serum concentration of Red Yeast Rice. Risk X: Avoid combination
Regorafenib: CYP3A4 Inhibitors (Moderate) may decrease serum concentrations of the active metabolite(s) of Regorafenib. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Regorafenib. Risk C: Monitor therapy
Ribociclib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ribociclib. Risk C: Monitor therapy
Rifabutin: Fosamprenavir may increase serum concentrations of the active metabolite(s) of Rifabutin. Rifabutin may increase the serum concentration of Fosamprenavir. Fosamprenavir may increase the serum concentration of Rifabutin. Management: Reduce rifabutin doses during fosamprenavir coadministration, by at least 50% when used with fosamprenavir alone or 75% (to a dose of 150 mg every other day or 3 times per week) when used with fosamprenavir/ritonavir. Risk D: Consider therapy modification
RifAMPin: May decrease the serum concentration of Fosamprenavir. Specifically, concentrations of amprenavir (active metabolite) may be decreased. Risk X: Avoid combination
Rimegepant: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Rimegepant. Management: If taking rimegepant for the acute treatment of migraine, avoid a second dose of rimegepant within 48 hours when used concomitantly with moderate CYP3A4 inhibitors. No dose adjustment needed if using rimegepant for prevention of episodic migraine. Risk D: Consider therapy modification
Rivaroxaban: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Rivaroxaban. This warning is more specifically for drugs that are inhibitors of both CYP3A4 and P-glycoprotein. For erythromycin, refer to more specific erythromycin-rivaroxaban monograph recommendations. Risk C: Monitor therapy
Roflumilast-Containing Products: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Roflumilast-Containing Products. Risk C: Monitor therapy
Rosuvastatin: Protease Inhibitors may increase the serum concentration of Rosuvastatin. Risk C: Monitor therapy
Rupatadine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Rupatadine. Risk C: Monitor therapy
Ruxolitinib (Systemic): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ruxolitinib (Systemic). Risk C: Monitor therapy
Salmeterol: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Salmeterol. Risk C: Monitor therapy
Saquinavir: May decrease serum concentrations of the active metabolite(s) of Fosamprenavir. Management: Consider alternatives to this combination. Safe and effective doses of fosamprenavir and saquinavir during coadministration have not been established. Risk X: Avoid combination
SAXagliptin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of SAXagliptin. Risk C: Monitor therapy
Selpercatinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Selpercatinib. Management: Avoid combination if possible. If use is necessary, reduce selpercatinib dose as follows: from 120 mg twice/day to 80 mg twice/day, or from 160 mg twice/day to 120 mg twice/day. Risk D: Consider therapy modification
Selumetinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Selumetinib. Management: Avoid concomitant use when possible. If combined, selumetinib dose reductions are recommended and vary based on body surface area and selumetinib dose. For details, see the full drug interaction monograph or selumetinib prescribing information. Risk D: Consider therapy modification
Sertindole: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Sertindole. Risk X: Avoid combination
Sildenafil: Protease Inhibitors may increase the serum concentration of Sildenafil. Management: Use of protease inhibitors and sildenafil for the treatment of PAH is contraindicated. If using sildenafil for the treatment of erectile dysfunction, limit the sildenafil dose to 25 mg and do not use more frequently than every 48 hours. Risk D: Consider therapy modification
Silodosin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Silodosin. Risk C: Monitor therapy
Simeprevir: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Simeprevir. Risk X: Avoid combination
Simvastatin: Fosamprenavir may increase the serum concentration of Simvastatin. Risk X: Avoid combination
Sirolimus (Conventional): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Sirolimus (Conventional). Management: Monitor for increased serum concentrations of sirolimus if combined with a moderate CYP3A4 inhibitor. Lower initial sirolimus doses or sirolimus dose reductions will likely be required. Risk D: Consider therapy modification
Sirolimus (Protein Bound): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Sirolimus (Protein Bound). Management: Reduce the dose of protein bound sirolimus to 56 mg/m2 when used concomitantly with a moderate CYP3A4 inhibitor. Risk D: Consider therapy modification
Solifenacin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Solifenacin. Risk C: Monitor therapy
Sonidegib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Sonidegib. Management: Avoid concomitant use of sonidegib and moderate CYP3A4 inhibitors when possible. When concomitant use cannot be avoided, limit CYP3A4 inhibitor use to less than 14 days and monitor for sonidegib toxicity (particularly musculoskeletal adverse reactions). Risk D: Consider therapy modification
St John's Wort: May decrease the serum concentration of Fosamprenavir. Risk X: Avoid combination
SUNItinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of SUNItinib. Risk C: Monitor therapy
Suvorexant: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Suvorexant. Management: The recommended dose of suvorexant is 5 mg daily in patients receiving a moderate CYP3A4 inhibitor. The dose can be increased to 10 mg daily (maximum dose) if necessary for efficacy. Risk D: Consider therapy modification
Tacrolimus (Systemic): Protease Inhibitors may decrease the metabolism of Tacrolimus (Systemic). Management: Consider reducing the tacrolimus dose to 1 mg once or twice per week if coadministered with protease inhibitors that are strong inhibitors of CYP3A4. Monitor response, plasma concentrations (as appropriate), and for signs of toxicity. Risk D: Consider therapy modification
Tacrolimus (Topical): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tacrolimus (Topical). Risk C: Monitor therapy
Tadalafil: Fosamprenavir may increase the serum concentration of Tadalafil. Management: Initiate tadalafil for pulmonary arterial hypertension at 20 mg after at least 1 week of fosamprenavir therapy. Increase to tadalafil 40 mg as tolerated. For erectile dysfunction, limit the tadalafil dose to 10 mg every 72 hours. Risk D: Consider therapy modification
Tamsulosin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tamsulosin. Risk C: Monitor therapy
Tazemetostat: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tazemetostat. Management: Avoid when possible. If combined, reduce tazemetostat dose from 800 mg twice daily to 400 mg twice daily, from 600 mg twice daily to 400 mg in AM and 200 mg in PM, or from 400 mg twice daily to 200 mg twice daily. Risk D: Consider therapy modification
Telithromycin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Telithromycin. Risk C: Monitor therapy
Temsirolimus: CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Temsirolimus. Specifically, concentrations of sirolimus may be increased. Risk C: Monitor therapy
Terfenadine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Terfenadine. Risk C: Monitor therapy
Tetrahydrocannabinol: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tetrahydrocannabinol. Risk C: Monitor therapy
Tetrahydrocannabinol and Cannabidiol: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tetrahydrocannabinol and Cannabidiol. Risk C: Monitor therapy
Tezacaftor and Ivacaftor: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tezacaftor and Ivacaftor. Management: If combined with moderate CYP3A4 inhibitors, give tezacaftor/ivacaftor in the morning, every other day; give ivacaftor in the morning, every other day on alternate days. Tezacaftor/ivacaftor dose depends on age and weight; see full Lexi-Interact monograph Risk D: Consider therapy modification
Thiotepa: CYP3A4 Inhibitors (Moderate) may decrease serum concentrations of the active metabolite(s) of Thiotepa. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Thiotepa. Risk C: Monitor therapy
Ticagrelor: CYP3A4 Inhibitors (Moderate) may decrease serum concentrations of the active metabolite(s) of Ticagrelor. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ticagrelor. Risk C: Monitor therapy
Tipranavir: Protease Inhibitors may increase the serum concentration of Tipranavir. Tipranavir may decrease the serum concentration of Protease Inhibitors. Risk X: Avoid combination
Tofacitinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tofacitinib. Risk C: Monitor therapy
Tolterodine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tolterodine. Risk C: Monitor therapy
Tolvaptan: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Tolvaptan. Management: Avoid this combination with Samsca brand of tolvaptan. Reduce dose for Jynarque brand: 90 mg AM and 30 mg PM, reduce to 45 mg AM and 15 mg PM; 60 mg AM and 30 mg PM, reduce to 30 mg AM and 15 mg PM; 45 mg AM and 15 mg PM, reduce to 15 mg AM and PM. Risk D: Consider therapy modification
Toremifene: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Toremifene. Risk C: Monitor therapy
Trabectedin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Trabectedin. Risk C: Monitor therapy
TraMADol: CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of TraMADol. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of TraMADol. Risk C: Monitor therapy
TraZODone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of TraZODone. Risk C: Monitor therapy
Triazolam: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Triazolam. Management: Consider triazolam dose reduction in patients receiving concomitant moderate CYP3A4 inhibitors. Risk D: Consider therapy modification
Ubrogepant: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ubrogepant. Management: Use an initial ubrogepant dose of 50 mg and avoid a second dose for 24 hours when used with moderate CYP3A4 inhibitors. Risk D: Consider therapy modification
Udenafil: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Udenafil. Risk C: Monitor therapy
Ulipristal: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Ulipristal. Risk C: Monitor therapy
Valbenazine: CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Valbenazine. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Valbenazine. Risk C: Monitor therapy
Valproate Products: Protease Inhibitors may decrease the serum concentration of Valproate Products. Risk C: Monitor therapy
Vardenafil: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Vardenafil. Management: Limit Levitra (vardenafil) dose to a single 5 mg dose within a 24-hour period if combined with moderate CYP3A4 inhibitors. Avoid concomitant use of Staxyn (vardenafil) and moderate CYP3A4 inhibitors. Combined use is contraindicated outside of the US. Risk D: Consider therapy modification
Vemurafenib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Vemurafenib. Risk C: Monitor therapy
Venetoclax: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Venetoclax. Management: Reduce the venetoclax dose by at least 50% in patients requiring concomitant treatment with moderate CYP3A4 inhibitors. Resume the previous venetoclax dose 2 to 3 days after discontinuation of moderate CYP3A4 inhibitors. Risk D: Consider therapy modification
Verapamil: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Verapamil. Risk C: Monitor therapy
Vilazodone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Vilazodone. Risk C: Monitor therapy
VinBLAStine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of VinBLAStine. Risk C: Monitor therapy
VinCRIStine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of VinCRIStine. Risk C: Monitor therapy
VinCRIStine (Liposomal): CYP3A4 Inhibitors (Moderate) may increase the serum concentration of VinCRIStine (Liposomal). Risk C: Monitor therapy
Vindesine: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Vindesine. Risk C: Monitor therapy
Vinflunine: CYP3A4 Inhibitors (Moderate) may increase serum concentrations of the active metabolite(s) of Vinflunine. CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Vinflunine. Risk C: Monitor therapy
Voclosporin: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Voclosporin. Management: Decrease the voclosporin dose to 15.8 mg in the morning and 7.9 mg in the evening when combined with moderate CYP3A4 inhibitors. Risk D: Consider therapy modification
Vorapaxar: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Vorapaxar. Risk C: Monitor therapy
Warfarin: Fosamprenavir may increase the serum concentration of Warfarin. Risk C: Monitor therapy
Zanubrutinib: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Zanubrutinib. Management: Decrease the zanubrutinib dose to 80 mg twice daily during coadministration with a moderate CYP3A4 inhibitor. Further dose adjustments may be required for zanubrutinib toxicities, refer to prescribing information for details. Risk D: Consider therapy modification
Zopiclone: CYP3A4 Inhibitors (Moderate) may increase the serum concentration of Zopiclone. Risk C: Monitor therapy
Based on the Health and Humans Services (HHS) perinatal HIV guidelines, fosamprenavir (unboosted or boosted with ritonavir) is not one of the recommended antiretroviral agents for use in patients with HIV infection who are trying to conceive.
Patients with HIV infection not planning to become pregnant may use any available type of contraception, considering possible drug interactions and contraindications of the specific method. Consult drug interactions database for more detailed information specific to use of fosamprenavir and specific contraceptive methods.
Viral suppression sustained below the limits of detection with antiretroviral therapy (ART) and modification of therapy (if needed) is recommended in all patients with HIV infection who are planning a pregnancy. Optimization of the health of the person who will become pregnant and a discussion of the potential risks and benefits of ART during pregnancy is also recommended prior to conception. In most cases, recommendations from the HHS perinatal HIV guidelines (based on data obtained from cisgender women) can be applied to transgender and gender diverse people assigned female sex at birth.
Health care providers caring for couples planning a pregnancy when one or both partners are diagnosed with HIV infection may contact the National Perinatal HIV Hotline (888-448-8765) for clinical consultation (HHS [perinatal] 2021).
Fosamprenavir crosses the human placenta.
Outcome information specific to fosamprenavir use in pregnancy is no longer being reviewed and updated in the Health and Human Services (HHS) perinatal guidelines. The HHS perinatal HIV guidelines do not recommend fosamprenavir (unboosted or boosted with ritonavir) as one of the recommended antiretroviral agents for use during pregnancy and patients who are pregnant should be changed to a preferred or alternative therapy.
Maternal antiretroviral therapy (ART) may be associated with adverse pregnancy outcomes, including preterm delivery, stillbirth, low birth weight, and small for GA infants. Actual risks may be influenced by maternal factors such as disease severity, GA at initiation of therapy, and specific ART regimen; therefore, close fetal monitoring is recommended. Because there is clear benefit to appropriate treatment, maternal ART should not be withheld due to concerns for adverse neonatal outcomes. Long-term follow-up is recommended for all infants exposed to antiretroviral medications; children not diagnosed with HIV infection but who were exposed to ART in utero or as a neonate and develop significant organ system abnormalities of unknown etiology (particularly of the CNS or heart) should be evaluated for potential metabolic dysfunction. The risk of hepatic dysfunction and gestational diabetes may be increased in pregnant patients taking protease inhibitors. Consider performing the standard glucose screening test earlier in pregnancy in patients who initiated protease inhibitor therapy prior to conception.
ART is recommended for all pregnant people with HIV infection to maximize their health, maintain the viral load below the limit of detection and reduce the risk of perinatal transmission. Therapy should be individualized following a discussion of the potential risks and benefits of treatment during pregnancy. Patients on fully suppressive regimens prior to pregnancy generally may continue the same regimen considering known pregnancy outcomes and pharmacokinetic data. Monitoring of patients who are pregnant is more frequent than in patients who are not pregnant. ART initiated during pregnancy can be modified after delivery. In most cases, recommendations from the HHS perinatal HIV guidelines (based on data obtained from cisgender women) can be applied to transgender and gender diverse people assigned female sex at birth.
Data collection to monitor pregnancy and infant outcomes following exposure to ART is ongoing. Health care providers are encouraged to enroll patients who are pregnant exposed to antiretroviral medications as early in pregnancy as possible in the Antiretroviral Pregnancy Registry (1-800-258-4263 or www.APRegistry.com).
Health care providers caring for pregnant patients with HIV infection and their infants may contact the National Perinatal HIV Hotline (888-448-8765) for clinical consultation (HHS [perinatal] 2021).
It is not known if fosamprenavir is present in breast milk.
Maternal or infant antiretroviral therapy does not completely eliminate the risk of postnatal HIV transmission. In addition, multiclass-resistant virus has been detected in breastfeeding infants despite maternal therapy. In the United States, where formula is usually accessible, affordable, safe, and sustainable, and the risk of infant mortality due to diarrhea and respiratory infections is low, the Health and Human Services perinatal HIV guidelines do not recommend breastfeeding for patients with HIV infection when safer infant feeding options are available.
Information is available for counseling and managing patients with HIV infection who are considering breastfeeding (888-448-8765). In most cases, recommendations from the HHS perinatal HIV guidelines (based on data obtained from cisgender women) can be applied to transgender and gender diverse people assigned female sex at birth (HHS [perinatal] 2021).
Adults should take oral suspension without food; however, pediatric patients should take oral suspension with food. Adult patients may take tablets without regard to food if not taken with ritonavir. Pediatric (HHS [pediatric] 2018) and adult patients should take tablets with food if taken with ritonavir.
Prior to initiation and periodically during therapy, monitor viral load, CD4 count, glucose; triglycerides and cholesterol; liver function tests (in patients with underlying hepatitis B or C)
Fosamprenavir is rapidly and almost completely converted to amprenavir by cellular phosphatases in vivo. Amprenavir binds to the site of HIV-1 protease activity and inhibits cleavage of viral Gag-Pol polyprotein precursors into individual functional proteins required for infectious HIV. This results in the formation of immature, noninfectious viral particles.
Absorption: 63%
Protein-binding: ~90% (to alpha1-acid glycoprotein); decreased in hepatic impairment
Metabolism: Fosamprenavir is rapidly and almost completely converted to amprenavir by cellular phosphatases in gut epithelium; amprenavir is hepatically metabolized via CYP isoenzymes (primarily CYP3A4); glucuronide conjugation of oxidized metabolites also occurs
Bioavailability: Not established; food does not have a significant effect on absorption of tablets. Administration of oral suspension with food reduced maximal drug concentration (Cmax) by 46% and area under the curve (AUC) by 28%.
Half-life elimination: ~7.7 hours (amprenavir)
Time to peak, plasma: 1.5 to 4 hours (median: 2.5 hours)
Excretion: Minimal excretion of unchanged drug in urine (1%) and feces; 75% of dose excreted as metabolites via biliary tract into feces and 14% excreted as metabolites in urine
Hepatic function impairment: AUC of amprenavir was increased by ~22% in mild hepatic impairment, by ~70% in moderate hepatic impairment, and by ~80% in severe hepatic impairment. Protein binding also decreased.
Pediatric: For children 2 to 18 years of age, the AUC is 31.4 to 93.4 mcg•h/mL, Cmax is 5 to 6.07 mcg/mL, and Cmin is 0.454 to 2.69 mcg/mL.
Suspension (Lexiva Oral)
50 mg/mL (per mL): $0.95
Tablets (Fosamprenavir Calcium Oral)
700 mg (per each): $20.83
Tablets (Lexiva Oral)
700 mg (per each): $23.17
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