| Analgesics |
| Anticholinergics |
| Antihistamines |
| Antispasmodics |
| Antidepressants |
| Antipsychotics |
| Cation-containing agents |
| Iron supplements |
| Aluminum (antacids, sucralfate) |
| Barium |
| Neurally active agents |
| Opiates |
| Antihypertensives |
| Ganglionic blockers |
| Vinca alkaloids |
| Calcium channel blockers |
| 5HT3 antagonists |
