DICYCLOMINE HYDROCHLORIDE (PRESERVATIVE FREE)
Clinical safety rating: safe
Other anticholinergic drugs can have additive effects Contraindicated in patients with glaucoma or severe ulcerative colitis.
Competitive antagonist of muscarinic acetylcholine receptors (M1, M2, M3) in the gastrointestinal tract, producing antispasmodic effects by reducing smooth muscle contractions.
| Metabolism | Hepatic (major pathway): N-desmethylation via CYP3A4, minor pathways via CYP2D6. |
| Excretion | Renal (approximately 50-80% as unchanged drug and metabolites), biliary/fecal (minor, <10%) |
| Half-life | 5-8 hours; may be prolonged in elderly or patients with hepatic impairment |
| Protein binding | ~90% bound to plasma proteins, primarily albumin |
| Volume of Distribution | 3.0-3.5 L/kg; indicates extensive tissue distribution |
| Bioavailability | Oral: approximately 67% (due to first-pass metabolism); Intramuscular: 100% |
| Onset of Action | Oral: 1-2 hours; Intramuscular: 10-30 minutes |
| Duration of Action | Oral: 3-4 hours; Intramuscular: 3-4 hours |
| Molecular Weight | 345.95 |
20 mg intramuscularly every 4-6 hours.
| Dosage form | INJECTABLE |
| Renal impairment | No specific adjustment required; use caution in severe impairment. |
| Liver impairment | No specific adjustment required; use caution in severe impairment. |
| Pediatric use | Not recommended for use in pediatric patients. |
| Geriatric use | Initiate at lower dose (10 mg) due to increased sensitivity to anticholinergic effects. |
| 1st trimester | Avoid use; crosses placenta; potential anticholinergic effects. |
| 2nd trimester | Avoid use; limited safety data; anticholinergic adverse effects possible. |
| 3rd trimester | Avoid use; may cause neonatal anticholinergic effects. |
Clinical note
Other anticholinergic drugs can have additive effects Contraindicated in patients with glaucoma or severe ulcerative colitis.
| FDA category | Animal |
| Placental transfer | Crosses placenta; detected in fetal serum. |
| Breastfeeding | Excreted into breast milk in small amounts; avoid due to potential anticholinergic effects in infant; use only if clearly needed. |
■ FDA Black Box Warning
No FDA boxed warning.
| Common Effects | Dry mouth |
| Serious Effects |
Obstructive uropathyObstructive disease of the gastrointestinal tractSevere ulcerative colitisReflux esophagitisUnstable cardiovascular status in acute hemorrhageMyasthenia gravisGlaucomaHypersensitivity to dicyclomine
| Precautions | May cause anticholinergic effects: dry mouth, blurred vision, constipation, urinary retention, heat intolerance, Use cautiously in patients with glaucoma, hepatic/renal impairment, hyperthyroidism, coronary artery disease, tachycardia, prostatic hyperplasia, myasthenia gravis, May impair mental alertness; caution when driving or operating machinery, Risk of misdiagnosis in patients with intestinal obstruction or acute abdomen |
| Food/Dietary | No specific food interactions. However, alcohol and central nervous system depressants may enhance sedative effects. Avoid excessive consumption of caffeine or acidic foods that may worsen GI symptoms. |
Loading safety data…
| Lactation Rating | L3 |
| Teratogenic Risk | Animal studies have not shown fetal harm; no adequate human studies in pregnancy. Risk cannot be ruled out. Avoid first trimester if possible. |
| Fetal Monitoring | Monitor maternal anticholinergic adverse effects; fetal heart rate monitoring not routinely indicated unless maternal toxicity occurs. |
| Fertility Effects | No known adverse effects on human fertility; animal studies show no impairment. |
| Clinical Pearls | Dicyclomine hydrochloride is an anticholinergic agent used for irritable bowel syndrome (IBS). It can cause blurred vision, dry mouth, and urinary retention. Avoid in patients with glaucoma, myasthenia gravis, or obstructive uropathy. Use with caution in elderly due to fall risk. |
| Patient Advice | Take exactly as prescribed; do not exceed 40 mg per day in divided doses. · Do not take if you have glaucoma, severe constipation, or trouble urinating. · Avoid driving or operating heavy machinery if you experience blurred vision or dizziness. · Report any painful or difficult urination to your doctor immediately. · Swallow capsules whole; do not crush or chew. |