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Doxazosin: Drug information

Doxazosin: Drug information
(For additional information see "Doxazosin: Patient drug information" and see "Doxazosin: Pediatric drug information")

For abbreviations, symbols, and age group definitions used in Lexicomp (show table)
Brand Names: US
  • Cardura;
  • Cardura XL
Brand Names: Canada
  • APO-Doxazosin;
  • JAMP-Doxazosin;
  • TEVA-Doxazosin
Pharmacologic Category
  • Alpha 1 Blocker;
  • Antihypertensive
Dosing: Adult

Note: If therapy is discontinued for more than several days, begin with initial dose and retitrate as needed due to risk of orthostatic hypotension.

Benign prostatic hyperplasia

Benign prostatic hyperplasia (monotherapy or combination therapy):

Note: In patients with moderate to severe predominant storage lower urinary tract symptoms, use in combination with beta-3 agonist or anticholinergic agent. In patients with a significantly enlarged prostate (prostate volume >30 mL, prostate-specific antigen >1.5 ng/dL, or palpable prostate enlargement on digital rectal exam), use in combination with 5-alpha reductase inhibitor (Ref).

Immediate release: Oral: Initial: 1 mg once daily in the morning or evening; may titrate by doubling the daily dose (eg, to 2 mg, then 4 mg, then 8 mg) at 1- to 2-week intervals up to 8 mg once daily based on patient response and tolerability; maximum dose: 8 mg/day.

Extended release: Oral: 4 mg once daily in the morning; may titrate based on response and tolerability after 3 to 4 weeks to 8 mg once daily; maximum dose: 8 mg/day.

Conversion to extended release from immediate release: If immediate release is normally taken in the evening, do not administer evening dose. Then start extended-release product the following morning at lowest dose (4 mg once daily) and titrate.

Hypertension

Hypertension (alternative agent):

Note: Not recommended for initial management but may be considered as additional therapy for resistant hypertension in patients who do not respond adequately to combination therapy with preferred agents (Ref).

Immediate release: Oral: Initial: 1 mg once daily; titrate gradually as needed based on response and tolerability up to a dose of 16 mg once daily (Ref).

Ureteral stone(s) expulsion

Ureteral stone(s) expulsion (off-label use):

Note: Consider for use in patients with ureteral stones >5 and ≤10 mm (Ref). Although most evidence exists for distal ureteral stones, given the low side effect profile of alpha-blockers, may consider use in patients with stones in any location of ureter (Ref). Additionally, may consider for use after shock wave lithotripsy to help pass stone fragments (Ref). A uroselective alpha-blocker (eg, tamsulosin) may be preferred to decrease risk of hypotension (Ref).

Immediate release: Oral: 4 mg once daily in the evening until stone passage or for up to 4 weeks (Ref).

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Kidney Impairment: Adult

The renal dosing recommendations are based upon the best available evidence and clinical expertise. Senior Editorial Team: Bruce Mueller, PharmD, FCCP, FASN, FNKF; Jason A. Roberts, PhD, BPharm (Hons), B App Sc, FSHP, FISAC; Michael Heung, MD, MS.

Altered kidney function: No dosage adjustment necessary for any degree of kidney dysfunction (Ref).

Hemodialysis, intermittent (thrice weekly): Not significantly dialyzed (Carlson 1986): No supplemental dose or dosage adjustment necessary (Ref).

Peritoneal dialysis: Unlikely to be significantly dialyzed (highly protein bound): No dosage adjustment necessary (Ref).

CRRT: No dosage adjustment necessary (Ref).

PIRRT (eg, sustained, low-efficiency diafiltration): No dosage adjustment necessary (Ref).

Dosing: Hepatic Impairment: Adult

Mild to moderate impairment (Child-Pugh class A or B): There are no dosage adjustments provided in the manufacturer’s labeling; use with caution.

Severe impairment (Child-Pugh class C): Use is not recommended.

Dosing: Pediatric

(For additional information see "Doxazosin: Pediatric drug information")

Note: If drug is discontinued for greater than several days, consider beginning with initial dose and retitrate as needed.

Dysfunctional voiding

Dysfunctional voiding: Limited data available, efficacy results variable: Children ≥3 years and Adolescents: Oral: Immediate release: Initial: 0.5 mg once daily at bedtime; some trials maintained a fixed dose; others titrated at weekly or biweekly intervals to effect as tolerated (maximum daily dose: 2 mg/day) (Ref). In some trials, a larger initial dose (1 mg/day) was used in patients weighing >40 to 50 kg (Ref).

Hypertension

Hypertension: Limited data available: Children and Adolescents: Oral: Immediate release: Initial: 1 mg/day; maximum daily dose: 4 mg/day (Ref).

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Kidney Impairment: Pediatric

There are no dosage adjustments provided in manufacturer's labeling; however, limited data suggest renal impairment does not significantly alter pharmacokinetic parameters.

Dosing: Hepatic Impairment: Pediatric

Mild to moderate impairment (Child Pugh class A or B): There are no dosage adjustments provided in the manufacturer’s labeling, use with caution.

Severe impairment (Child-Pugh class C): There are no pediatric specific recommendations; however, based on experience in adult patients, use is not recommended.

Dosing: Older Adult

Refer to adult dosing.

Avoid use for hypertension treatment (alternative agents have superior risk-benefit profiles) (Ref).

Dosage Forms: US

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Cardura: 1 mg

Cardura: 1 mg, 2 mg [scored]

Cardura: 2 mg [scored; contains fd&c yellow #6 (sunset yellow), quinoline yellow (d&c yellow #10)]

Cardura: 4 mg [scored]

Cardura: 4 mg [scored; contains fd&c yellow #6 (sunset yellow)]

Generic: 1 mg, 2 mg, 4 mg

Tablet, Oral, as mesylate:

Cardura: 8 mg [scored; contains fd&c blue #2 (indigotine), quinoline yellow (d&c yellow #10)]

Generic: 8 mg

Tablet Extended Release 24 Hour, Oral:

Cardura XL: 4 mg, 8 mg

Generic Equivalent Available: US

May be product dependent

Dosage Forms: Canada

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Generic: 1 mg, 2 mg, 4 mg

Administration: Adult

Oral:

Extended release: Swallow tablets whole; do not crush, cut, chew, or divide. Administer with morning meal.

Bariatric surgery: Some institutions may have specific protocols that conflict with these recommendations; refer to institutional protocols as appropriate. Switch to IR formulation.

Immediate release: Administer daily dose either in the morning or evening.

Administration: Pediatric

Oral: Immediate release: Administer without regard to meals at the same time each day

Use: Labeled Indications

Benign prostatic hyperplasia: Treatment of signs and symptoms of benign prostatic hyperplasia.

Hypertension (immediate release only): Management of hypertension. Note: Alpha blockers are not recommended as first-line therapy (ACC/AHA [Whelton 2018]).

Use: Off-Label: Adult

Ureteral stone(s), expulsion

Medication Safety Issues
Sound-alike/look-alike issues:

Doxazosin may be confused with doxapram, doxepin, DOXOrubicin

Cardura may be confused with Cardene, Cordarone, Cordran, Coumadin, K-Dur, Ridaura

Older Adult: High-Risk Medication:

Beers Criteria: Doxazosin is identified in the Beers Criteria as a potentially inappropriate medication for hypertension in patients 65 years and older due to its high risk of orthostatic hypotension. Avoid use for hypertension treatment (alternative agents have superior risk-benefit profiles) (Beers Criteria [AGS 2019]).

Adverse Reactions (Significant): Considerations
Floppy iris syndrome

Intraoperative floppy iris syndrome (IFIS) has been reported in patients with current or prior use of alpha-1 blockers undergoing cataract surgery (Ref). Studies report significantly higher surgical complication rates for patients who experience IFIS (Ref).

Mechanism: Not completely established; may be related to a combination of the pharmacologic action (ie, inhibition of the iris dilator smooth muscle contraction) and long-term smooth muscle atrophy from accumulation in iris pigment epithelial cells (Ref).

Onset: Varied; may occur with current (within a few days to months of initiation) or prior use (years following discontinuation) (Ref). A minimum 3-month duration of alpha-1 blocker use has been proposed as a risk for IFIS (Ref).

Risk factors:

• Individual alpha-1 blocker (risk highest with tamsulosin) (Ref)

• Hypertension (Ref)

• Males (Ref)

• Older age (Ref)

• Decreased preoperative dilated pupil diameter (Ref)

Orthostatic hypotension

Doxazosin is associated with orthostatic hypotension, which can manifest as dizziness and vertigo; however, some studies suggest that the differences in blood pressure reduction in the standing versus sitting position are not significantly different with use of doxazosin (Ref).

Mechanism: Dose-related; related to the pharmacologic action (ie, inhibition of vascular smooth muscle contraction and vasodilation) (Ref).

Onset: Varied; “first dose” orthostatic hypotension may occur 2 to 6 hours after dose. However, has also occurred months after initiation (Ref).

Risk factors:

• Individual alpha-1 blocker (risk lowest with tamsulosin) (Ref)

• First dose or redose after dose interruption (Ref)

• Rapid increase in dose

• Concurrent medications that cause orthostatic hypotension (eg, antihypertensives, nitrates, phosphodiesterase-5 inhibitors) (Ref)

• Females >65 years of age (Ref)

• Alcohol use (Ref)

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Adverse reactions reported in adults.

>10%: Nervous system: Dizziness (≤19%) (table 1), fatigue (≤12%), malaise (≤12%), vertigo (≤16%) (table 2)

Doxazosin: Adverse Reaction: Dizziness

Drug (Doxazosin)

Placebo

Dose

Dosage Form

Indication

Number of Patients (Doxazosin)

Number of Patients (Placebo)

Comments

16%

9%

1 to 16 mg once daily in hypertensives and 0.5 to 8 mg once daily in normotensives

Immediate-release tablets

Benign prostatic hyperplasia

665

300

Including vertigo

19%

9%

1 to 16 mg once daily

Immediate-release tablets

Hypertension

339

336

N/A

9%

2%

1 to 8 mg once daily

Immediate-release tablets

Hypertension

651

156

N/A

5%

2%

4 to 8 mg once daily

Extended-release tablets

Hypertension

666

156

N/A

Doxazosin: Adverse Reaction: Vertigo

Drug (Doxazosin)

Placebo

Dose

Dosage Form

Indication

Number of Patients (Doxazosin)

Number of Patients (Placebo)

Comments

16%

9%

1 to 16 mg once daily in hypertensives and 0.5 to 8 mg once daily in normotensives

Immediate-release tablets

Benign prostatic hyperplasia

665

300

Including dizziness

4%

0.6%

1 to 8 mg once daily

Immediate-release tablets

Hypertension

651

156

N/A

2%

0.6%

4 to 8 mg once daily

Extended-release tablets

Hypertension

666

156

N/A

1% to 10%:

Cardiovascular: Edema (≤3%), hypotension (≤2%), orthostatic hypotension (1% to 2%) (table 3)

Doxazosin: Adverse Reaction: Orthostatic Hypotension

Drug (Doxazosin)

Placebo

Dose

Dosage Form

Indication

Number of Patients (Doxazosin)

Number of Patients (Placebo)

2%

0.6%

1 to 8 mg once daily

Immediate-release tablets

Hypertension

651

156

1%

0.6%

4 to 8 mg once daily

Extended-release tablets

Hypertension

666

156

Gastrointestinal: Abdominal pain (2%), dyspepsia (1%), nausea (1% to 2%), xerostomia (1%)

Genitourinary: Urinary tract infection (1%)

Nervous system: Asthenia (4% to 7%), drowsiness (1% to 5%), headache (6%)

Neuromuscular & skeletal: Myalgia (≤1%)

Renal: Polyuria (2%)

Respiratory: Dyspnea (1% to 3%), respiratory tract infection (5%), rhinitis (3%)

<1%:

Cardiovascular: Angina pectoris, chest pain, palpitations, syncope, tachycardia

Endocrine & metabolic: Decreased libido, hot flash

Gastrointestinal: Diarrhea

Genitourinary: Dysuria, impotence

Neuromuscular & skeletal: Arthralgia

Respiratory: Epistaxis

Frequency not defined: Hematologic & oncologic: Decreased neutrophils

Postmarketing:

Cardiovascular: Acute myocardial infarction, bradycardia (Pigot 2022), cardiac arrhythmia

Dermatologic: Alopecia, pruritus, skin rash, urticaria

Endocrine & metabolic: Gynecomastia (Viola 2014)

Gastrointestinal: Anorexia, gastrointestinal obstruction, vomiting

Genitourinary: Hematuria, nocturia, priapism (Avisrror 2000), urinary frequency

Hematologic & oncologic: Leukopenia, purpuric disease, thrombocytopenia

Hepatic: Abnormal hepatic function tests, cholestatic hepatitis, hepatitis, jaundice

Hypersensitivity: Angioedema (Piller 2006)

Nervous system: Agitation, cerebrovascular accident (Mansoor 2002), hypoesthesia, myasthenia, nervousness, paresthesia

Neuromuscular & skeletal: Muscle cramps

Ophthalmic: Blurred vision, intraoperative floppy iris syndrome (cataract surgery) (Haridas 2013)

Respiratory: Aggravated bronchospasm

Contraindications

Hypersensitivity to doxazosin, other quinazolines (eg, prazosin, terazosin), or any component of the formulation.

Canadian labeling: Additional contraindications (not in US labeling): Galactose intolerance, the congenital lactase deficiency or glucose-galactose malabsorption.

Warnings/Precautions

Concerns related to adverse effects:

• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks that require mental alertness (eg, operating machinery or driving).

• Hematologic effect: Decreases in WBC and neutrophil count have been reported; WBC and neutrophils returned to normal after discontinuation.

Disease-related concerns:

• Cardiovascular disease: Use with caution in patients with heart failure, angina pectoris, or recent acute myocardial infarction (within the last 6 months). If symptoms of angina pectoris appear or worsen, discontinue use. In a scientific statement from the American Heart Association, doxazosin has been determined to be an agent that may exacerbate underlying myocardial dysfunction (magnitude: moderate) (AHA [Page 2016]).

• Hepatic impairment: Use with caution in patients with mild to moderate impairment (Child-Pugh class A and B); monitor blood pressure and for symptoms of hypotension. Not recommended in severe impairment (Child-Pugh class C) (extensively metabolized).

Special populations:

• Cataract surgery patients: Intraoperative floppy iris syndrome has been observed in cataract surgery patients who were on or were previously treated with alpha-1 blockers; there appears to be no benefit in discontinuing alpha-blocker therapy prior to surgery. May require modifications to surgical technique; instruct patients to inform ophthalmologist of current or previous alpha-1 blocker use when considering eye surgery.

Dosage form specific issues:

• Extended release: Consists of drug within a nondeformable matrix; following drug release/absorption, the matrix/shell is expelled in the stool. The use of nondeformable products in patients with known stricture/narrowing of the GI tract has been associated with symptoms of obstruction. Use caution in patients with increased GI retention (eg, chronic constipation) as doxazosin exposure may be increased.

Other warning/precautions:

• Appropriate use: Extended release: Not indicated for use in women or for the treatment of hypertension.

Metabolism/Transport Effects

Substrate of CYP2C19 (minor), CYP2D6 (minor), CYP3A4 (minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential

Drug Interactions

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.

Alpha-/Beta-Agonists: Alpha1-Blockers may diminish the vasoconstricting effect of Alpha-/Beta-Agonists. Similarly, Alpha-/Beta-Agonists may antagonize Alpha1-Blocker vasodilation. Risk C: Monitor therapy

Alpha1-Agonists: Alpha1-Blockers may diminish the vasoconstricting effect of Alpha1-Agonists. Similarly, Alpha1-Agonists may antagonize Alpha1-Blocker vasodilation. Risk C: Monitor therapy

Alpha1-Blockers: May enhance the antihypertensive effect of other Alpha1-Blockers. Risk X: Avoid combination

Amifostine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Amifostine. Management: When used at chemotherapy doses, hold blood pressure lowering medications for 24 hours before amifostine administration. If blood pressure lowering therapy cannot be held, do not administer amifostine. Use caution with radiotherapy doses of amifostine. Risk D: Consider therapy modification

Amphetamines: May diminish the antihypertensive effect of Antihypertensive Agents. Risk C: Monitor therapy

Antipsychotic Agents (Second Generation [Atypical]): Blood Pressure Lowering Agents may enhance the hypotensive effect of Antipsychotic Agents (Second Generation [Atypical]). Risk C: Monitor therapy

Barbiturates: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Risk C: Monitor therapy

Benperidol: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Risk C: Monitor therapy

Beta-Blockers: May enhance the orthostatic hypotensive effect of Alpha1-Blockers. The risk associated with ophthalmic products is probably less than systemic products. Risk C: Monitor therapy

Brigatinib: May diminish the antihypertensive effect of Antihypertensive Agents. Brigatinib may enhance the bradycardic effect of Antihypertensive Agents. Risk C: Monitor therapy

Brimonidine (Topical): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Risk C: Monitor therapy

Bromperidol: May diminish the hypotensive effect of Blood Pressure Lowering Agents. Blood Pressure Lowering Agents may enhance the hypotensive effect of Bromperidol. Risk X: Avoid combination

Calcium Channel Blockers: Alpha1-Blockers may enhance the hypotensive effect of Calcium Channel Blockers. Risk C: Monitor therapy

CYP3A4 Inhibitors (Strong): May increase the serum concentration of Doxazosin. Risk C: Monitor therapy

Dapoxetine: May enhance the orthostatic hypotensive effect of Alpha1-Blockers. Risk C: Monitor therapy

Dexmethylphenidate: May diminish the therapeutic effect of Antihypertensive Agents. Risk C: Monitor therapy

Diazoxide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Risk C: Monitor therapy

DULoxetine: Blood Pressure Lowering Agents may enhance the hypotensive effect of DULoxetine. Risk C: Monitor therapy

Flunarizine: May enhance the therapeutic effect of Antihypertensive Agents. Risk C: Monitor therapy

Herbal Products with Blood Pressure Increasing Effects: May diminish the antihypertensive effect of Antihypertensive Agents. Risk C: Monitor therapy

Herbal Products with Blood Pressure Lowering Effects: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Risk C: Monitor therapy

Hypotension-Associated Agents: Blood Pressure Lowering Agents may enhance the hypotensive effect of Hypotension-Associated Agents. Risk C: Monitor therapy

Levodopa-Containing Products: Blood Pressure Lowering Agents may enhance the hypotensive effect of Levodopa-Containing Products. Risk C: Monitor therapy

Loop Diuretics: May enhance the hypotensive effect of Antihypertensive Agents. Risk C: Monitor therapy

Lormetazepam: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Risk C: Monitor therapy

Methylphenidate: May diminish the antihypertensive effect of Antihypertensive Agents. Risk C: Monitor therapy

Molsidomine: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Risk C: Monitor therapy

Nicorandil: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Risk C: Monitor therapy

Nitroprusside: Blood Pressure Lowering Agents may enhance the hypotensive effect of Nitroprusside. Risk C: Monitor therapy

Obinutuzumab: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Management: Consider temporarily withholding blood pressure lowering medications beginning 12 hours prior to obinutuzumab infusion and continuing until 1 hour after the end of the infusion. Risk D: Consider therapy modification

Pentoxifylline: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Risk C: Monitor therapy

Pholcodine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Pholcodine. Risk C: Monitor therapy

Phosphodiesterase 5 Inhibitors: May enhance the hypotensive effect of Alpha1-Blockers (Nonselective). Management: Ensure patient is stable on one agent prior to initiating the other, and always initiate combination using the lowest possible dose of the drug being added. When tadalafil is used for treatment of BPH, concurrent alpha 1-blockers are not recommended. Risk D: Consider therapy modification

Prostacyclin Analogues: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Risk C: Monitor therapy

Quinagolide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Risk C: Monitor therapy

Rilmenidine: Alpha1-Blockers may enhance the hypotensive effect of Rilmenidine. Risk C: Monitor therapy

Pregnancy Considerations

Doxazosin crosses the placenta (Versmissen 2016).

Chronic maternal hypertension may increase the risk of birth defects, low birth weight, preterm delivery, stillbirth, and neonatal death. Actual fetal/neonatal risks may be related to duration and severity of maternal hypertension. Untreated hypertension may also increase the risks of adverse maternal outcomes, including gestational diabetes, myocardial infarction, preeclampsia, stroke, and delivery complications (ACOG 203 2019).

Agents other than doxazosin are more commonly used to treat hypertension in pregnancy (ACOG 203 2019; ESC [Regitz-Zagrosek 2018]). Females with preexisting hypertension may continue their medication during pregnancy unless contraindications exist (ESC [Regitz-Zagrosek 2018]). Although rare, use of doxazosin for the treatment of hypertension due to a pheochromocytoma during pregnancy has been described; treatment was generally started after the first trimester (Lenders 2019; van der Weerd 2017).

Breastfeeding Considerations

Doxazosin is present in breast milk.

Information is available from a single case report following a maternal dose of doxazosin 4 mg every 24 hours for 2 doses for urinary stones. Milk samples were obtained at various intervals over 24 hours, beginning ~17 hours after the first dose. Maternal serum samples were obtained at nearly the same times, beginning ~1 hour later. The highest serum and milk concentrations of doxazosin were observed ~1 hour after the dose. Using the highest milk concentration (4.15 mcg/L), the estimated dose to the breastfeeding infant was calculated to be <1% of the weight-adjusted maternal dose (Jensen, 2013). In general, breastfeeding is considered acceptable when the relative infant dose of a medication is <10% (Anderson 2016; Ito 2000).

In a second case report, doxazosin was not present in breast milk when sampled 30 hours after the last maternal dose. In this case, maternal doxazosin was administered for hypertension due to a pheochromocytoma, surgically removed after delivery. Doxazosin 4 mg once daily was used during pregnancy, increased to 6 mg/day prior to delivery, and 8 mg/day 3 days' postpartum prior to being discontinued (Versmissen 2016).

Dietary Considerations

Administer extended-release tablet with morning meal.

Monitoring Parameters

BP routinely and for at least 6 hours after initial dose and with each dose increase (standing and sitting/supine); monitor patients with mild to moderate impairment for symptoms of hypotension; prostate cancer screening prior to initiation and then as directed.

Benign prostatic hyperplasia: International Prostate Symptom Score (baseline and 4 to 12 weeks after treatment initiation); urinalysis (baseline); objective and subjective signs of relief of benign prostatic hyperplasia and lower urinary tract symptoms (AUA [Lerner 2021]).

Hypertension: The 2017 Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults (ACC/AHA [Whelton 2018]):

Confirmed hypertension and known CVD or 10-year ASCVD risk ≥10%: Target blood pressure <130/80 mm Hg is recommended

Confirmed hypertension without markers of increased ASCVD risk: Target blood pressure <130/80 mm Hg may be reasonable

Mechanism of Action

Hypertension: Competitively inhibits postsynaptic alpha1-adrenergic receptors which results in vasodilation of veins and arterioles and a decrease in total peripheral resistance and blood pressure; ~50% as potent on a weight by weight basis as prazosin.

BPH: Competitively inhibits postsynaptic alpha1-adrenergic receptors in prostatic stromal and bladder neck tissues. This reduces the sympathetic tone-induced urethral stricture causing BPH symptoms.

Pharmacokinetics

Duration: >24 hours

Protein binding: ~98%

Metabolism: Extensively hepatic to active metabolites; primarily via CYP3A4; secondary pathways involve CYP2D6 and 2C9

Bioavailability: Immediate release: ~65%; Extended release relative to immediate release: 54% to 59%

Half-life elimination: Immediate release: ~22 hours; Extended release: 15 to 19 hours

Time to peak, serum: Immediate release: 2 to 3 hours; Extended release: 8 ± 3.7 to 9 ± 4.7 hours

Excretion: Feces (~63%, primarily as metabolites [4.8% as unchanged]); urine (9%, primarily as metabolites)

Pharmacokinetics: Additional Considerations

Hepatic function impairment: Immediate release: 40% increase in exposure in mild impairment (Child-Pugh class A).

Older adult: Extended release: Cmax and AUC increased 27% and 34% respectively in elderly patients.

Pricing: US

Tablet, 24-hour (Cardura XL Oral)

4 mg (per each): $7.07

8 mg (per each): $7.79

Tablets (Cardura Oral)

1 mg (per each): $6.15

2 mg (per each): $6.15

4 mg (per each): $6.45

8 mg (per each): $7.11

Tablets (Doxazosin Mesylate Oral)

1 mg (per each): $1.02 - $1.35

2 mg (per each): $0.97 - $1.35

4 mg (per each): $1.03 - $1.42

8 mg (per each): $1.49

Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.

Brand Names: International
  • Alfadil (SE);
  • Alfadil XL (PH);
  • Alfadoxin (CL);
  • Ascalan (AT);
  • Barova 4 (TH);
  • Cadex (IL);
  • Cadil (KR);
  • Cadlin (KR);
  • Cardenalin (JP);
  • Cardolin-2 (TH);
  • Cardular (DE, LB);
  • Cardular PP (DE);
  • Cardular Uro (DE);
  • Cardura (AE, AR, BB, BG, BH, CL, CO, CR, CY, CZ, DO, EG, GB, GR, GT, HK, HN, HU, ID, IE, IQ, IR, JO, KW, LT, LU, LY, MT, MX, MY, NI, NL, OM, PA, PK, PT, QA, RU, SA, SG, SV, SY, TH, TR, UA, UY, VE, YE, ZA, ZM);
  • Cardura CR (CH);
  • Cardura XL (CL, CN, CO, CR, DO, EE, GT, HK, HN, LT, LU, MT, MY, NI, PA, PE, PL, RO, SI, SK, SV, TH, ZW);
  • Cardura-XL S.R. (KR);
  • Carduran (AU, NO);
  • Carduran Neo (ES);
  • Carduran Retard (DK, IS);
  • Carduran XL (BR);
  • Cazosin (TH);
  • Curcard (BH, LB);
  • Dalgen (CO);
  • Dedralen (IT);
  • Diblocin (DE);
  • Diblocin PP (DE);
  • Diblocin Uro (DE);
  • Doka (HR);
  • Dophilin (TW);
  • Dorbantil (PY);
  • Dosabin (TW);
  • Dosan (NZ);
  • Dosin (BH, EG);
  • Dovozin (TH);
  • Doxaben (TW);
  • Doxaben XL (TW);
  • Doxacar (IE);
  • Doxacard (IN);
  • Doxacin (LB);
  • Doxacor (EG, PE);
  • Doxagamma (DE);
  • Doxan (TW);
  • Doxane (IE);
  • Doxatan (IE, MT);
  • Doxazone XL SR (KR);
  • Doxino (HK);
  • Doxolbran (AR);
  • Genzosin (TW);
  • Hibradren (AT);
  • Kamiren (CZ, HR, RO);
  • Kamiren XL (HK, MY, RO);
  • Kinxaben (TW);
  • Maguran (GR);
  • Magurol (JO, LK, MT, MY);
  • Mahurol (UA);
  • Myocard (DK);
  • Pencor (HK, MY, SG, TH);
  • Progandol (ES);
  • Prostasin (TH);
  • Pzocin XL (KR);
  • Saxobin (TW);
  • Supressin (AT);
  • Tarzos (EG);
  • Tonocardin (HR);
  • Tonokardin (HR);
  • Uriduct (DE);
  • Xadosin (TW);
  • Xadosin XL (TW);
  • Zoxan (VN);
  • Zoxan LP (FR);
  • Zoxon (CZ, UA)


For country code abbreviations (show table)
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