Propantheline bromide inhibits gastrointestinal motility and diminishes gastric acid secretion. The drug also inhibits the action of acetylcholine at the postganglionic nerve endings of the parasympathetic nervous system.
Propantheline bromide is extensively metabolized in man primarily by hydrolysis to the inactive materials xanthene-9-carboxylic acid and (2-hydroxyethyl) diisopropylmethylammonium bromide. In a bioavailability study, peak plasma concentrations of propantheline were achieved in about one hour, following a single oral dose.
The plasma elimination half-life of propantheline is about 1.6 hours. Approximately 70% of the dose is excreted in the urine, mostly as metabolites. The urinary excretion of propantheline is about 3% after oral tablet administration.
Dosage & Administration
Adult dose: The usual initial adult dose of propantheline bromide tablets is 15 mg taken 30 minutes before each meal and 30 mg at bedtime (a total of 75 mg daily). Subsequent dosage adjustment should be made according to the patient’s individual response and tolerance.
Pediatric Use: Safety and effectiveness in children have not been established.
Anticholinergics may delay absorption of other medication given concomitantly. Excessive cholinergic blockade may occur if propantheline is given concomitantly with belladonna alkaloids or synthetic and semisynthetic anticholinergic agents, narcotic analgesics such as meperidine, Type 1 antiarrhythmic drugs (e.g., disopyramide, procainamide, or quinidine), antihistamines, phenothiazines, tricyclic antidepressants, or other psychoactive drugs. Propantheline may also potentiate the sedative effect of phenothiazines. Increased intraocular pressure may result from concurrent administration of anticholinergics and corticosteroids.
Concurrent use of propantheline with slow-dissolving tablets of digoxin may cause increased serum digoxin levels. This interaction can be avoided by using only those digoxin tablets that rapidly dissolve by USP standards.
Propantheline is contraindicated in patients with:
- Glaucoma, since mydriasis is to be avoided.
- Obstructive disease of the gastrointestinal tract (pyloroduodenal stenosis, achalasia, paralytic ileus, etc.).
- Obstructive uropathy (e.g., bladder-neck obstruction due to prostatic hypertrophy).
- Intestinal atony of elderly or debilitated patients.
- Severe ulcerative colitis or toxic megacolon complicating ulcerative colitis.
- Unstable cardiovascular adjustment in acute hemorrhage.
- Myasthenia gravis.
Pregnancy & Lactation
Pregnancy Category C. Animal reproduction studies have not been conducted with propantheline. It is also not known whether propantheline can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Propantheline should be given to a pregnant woman only if clearly needed.
Nursing Mothers: It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when propantheline is administered to a nursing woman. Suppression of lactation may occur with anticholinergic drugs.