METHSCOPOLAMINE BROMIDE
Clinical safety rating: safe
Other anticholinergic drugs can have additive effects Can cause drowsiness and confusion.
Antimuscarinic agent that competitively antagonizes acetylcholine at muscarinic receptors, inhibiting gastrointestinal motility and secretions.
| Metabolism | Primarily hepatic via hydrolysis and conjugation. |
| Excretion | Primarily renal excretion of unchanged drug and metabolites; approximately 60-70% excreted in urine within 24 hours, with the remainder eliminated in feces via biliary excretion. |
| Half-life | Terminal elimination half-life is approximately 1.5-2 hours in adults; clinical context: requires frequent dosing (every 4-6 hours) to maintain therapeutic effect. |
| Protein binding | Approximately 30-50% bound primarily to albumin; low binding suggests minimal displacement interactions. |
| Volume of Distribution | Vd approximately 2-4 L/kg; indicates extensive distribution into tissues, including the central nervous system (quaternary ammonium structure limits CNS penetration). |
| Bioavailability | Oral: 10-25% due to poor absorption and first-pass metabolism; Intramuscular: approximately 100%. |
| Onset of Action | Oral: 30-60 minutes; Intramuscular: 10-20 minutes; Intravenous: within 2-5 minutes. |
| Duration of Action | Oral: 4-6 hours; Parenteral: 3-4 hours; clinical notes: shorter duration with IV administration due to rapid redistribution. |
2.5 to 5 mg orally three times daily and at bedtime; or 0.25 to 1 mg subcutaneously or intramuscularly every 6 to 8 hours.
| Dosage form | TABLET |
| Renal impairment | No specific guidelines; use with caution in severe renal impairment (CrCl <30 mL/min) due to potential for anticholinergic toxicity. |
| Liver impairment | No specific guidelines; use with caution in severe hepatic impairment (Child-Pugh class C) due to reduced metabolism. |
| Pediatric use | Safety and efficacy not established in pediatric patients; no standard weight-based dosing available. |
| Geriatric use | Initiate at lower end of dosing range due to increased sensitivity to anticholinergic effects (e.g., confusion, constipation, urinary retention). |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other anticholinergic drugs can have additive effects Can cause drowsiness and confusion.
| FDA category | Animal |
| Breastfeeding | Methscopolamine bromide is excreted into breast milk in small amounts. M/P ratio is unknown. Anticholinergic effects in the infant are unlikely due to low oral bioavailability. However, caution is advised; monitor infant for anticholinergic symptoms (e.g., constipation, dry mouth, tachycardia). |
| Teratogenic Risk | Methscopolamine bromide is an anticholinergic agent. Data in pregnant women are limited. Animal studies have not been reported. Anticholinergics as a class are not strongly associated with major malformations. Potential risks include transient neonatal anticholinergic effects (e.g., ileus, tachycardia) if used near term. Use only if clearly needed. |
■ FDA Black Box Warning
None.
| Common Effects | nausea |
| Serious Effects |
["Glaucoma (particularly angle-closure)","Obstructive uropathy (e.g., bladder neck obstruction due to prostatic hypertrophy)","Obstructive diseases of the gastrointestinal tract (e.g., pyloroduodenal stenosis)","Myasthenia gravis","Toxic megacolon","Severe ulcerative colitis","Hepatic or renal impairment with risk of toxicity","Hypersensitivity to methscopolamine bromide or any component"]
| Precautions | ["May cause blurred vision (avoid driving or operating machinery until effects resolve)","Use caution in patients with glaucoma, prostatic hyperplasia, or urinary retention","May precipitate acute angle-closure glaucoma","Use in high environmental temperatures may cause heat stroke","Elderly patients may be more sensitive to anticholinergic effects"] |
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| Fetal Monitoring | Monitor maternal heart rate and blood pressure due to anticholinergic effects. In the fetus, assess heart rate variability; tachycardia may occur. In neonates, observe for transient anticholinergic effects (e.g., decreased gastrointestinal motility, urinary retention). |
| Fertility Effects | No specific human data on fertility. Anticholinergic agents may theoretically interfere with ovulation via hypothalamic-pituitary effects, but clinical significance is unclear. No known impact on spermatogenesis. |