PROPANTHELINE BROMIDE
Clinical safety rating: safe
Animal studies have demonstrated safety
Antimuscarinic; competitively blocks acetylcholine at postganglionic muscarinic receptors, inhibiting parasympathetic nerve impulses.
| Metabolism | Hepatic metabolism via ester hydrolysis; major metabolites include xanthene-9-carboxylic acid and diisopropylamine ethanol. |
| Excretion | Approximately 70% renal (tubular secretion) as metabolites and unchanged drug; 30% biliary/fecal. |
| Half-life | Terminal half-life 2.5-4 hours; clinically, dosing every 6 hours maintains therapeutic levels. |
| Protein binding | Less than 5% bound; primarily to albumin. |
| Volume of Distribution | 0.9-1.2 L/kg; indicates widespread tissue distribution. |
| Bioavailability | Oral: 10-30% due to extensive first-pass metabolism. |
| Onset of Action | Oral: 30-45 minutes; IV: 1-2 minutes. |
| Duration of Action | Oral: 4-6 hours (up to 8 hours with extended release); IV: 2-4 hours. |
15 mg orally 3 times daily before meals and 30 mg at bedtime; initial dose may be 15 mg 3 times daily.
| Dosage form | TABLET |
| Renal impairment | GFR 30-50 mL/min: reduce dose to 7.5 mg 3 times daily; GFR <30 mL/min: avoid use. |
| Liver impairment | Child-Pugh class B: reduce dose by 50%; Child-Pugh class C: avoid use. |
| Pediatric use | Infants and children: 1-2 mg/kg/day orally divided every 6-8 hours; maximum 75 mg/day. |
| Geriatric use | Initiate at 7.5 mg orally 2-3 times daily due to increased anticholinergic sensitivity; titrate cautiously. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other anticholinergic drugs can have additive effects Contraindicated in patients with glaucoma or severe ulcerative colitis.
| Breastfeeding | M/P ratio unknown. Propantheline bromide passes into breast milk in small amounts; anticholinergic effects in the infant are possible (e.g., constipation, urinary retention). Caution advised; consider alternatives. |
| Teratogenic Risk | Category C. First trimester: Limited human data; animal studies show fetal resorption and delayed ossification at high doses. Second and third trimesters: No specific malformation patterns; potential for anticholinergic effects (tachycardia, decreased GI motility) in the newborn if used near term. |
■ FDA Black Box Warning
None
| Common Effects | GI spasms |
| Serious Effects |
Hypersensitivity to propantheline; glaucoma (narrow-angle); obstructive uropathy (e.g., bladder neck obstruction due to prostatic hypertrophy); obstructive GI tract disease (e.g., pyloroduodenal stenosis); paralytic ileus; intestinal atony in elderly or debilitated patients; severe ulcerative colitis; toxic megacolon; myasthenia gravis; unstable cardiovascular status in acute hemorrhage.
| Precautions | Use with caution in patients with autonomic neuropathy, hepatic or renal disease, hyperthyroidism, coronary artery disease, congestive heart failure, cardiac arrhythmias, hypertension, hiatal hernia, prostatic hypertrophy, and in hot or humid environments (risk of heat stroke). May cause drowsiness or blurred vision. |
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| Fetal Monitoring | Monitor maternal heart rate, urinary retention, and GI motility. Fetal monitoring should include heart rate assessment during prolonged use; consider non-stress test if signs of fetal distress. |
| Fertility Effects | No direct evidence of impaired fertility in humans. Animal studies reported reduced implantation rates at high doses. Theoretical anticholinergic effects on reproductive tract secretions may alter cervical mucus. |