Bentyl (Dicyclomine Hydrochloride) - Drug Interactions, Contraindications, Overdosage

DRUG INTERACTIONS

Drug Interactions

The following agents may increase certain actions or side effects of anticholinergic drugs: amantadine, antiarrhythmic agents of Class I (e.g., quinidine), antihistamines, antipsychotic agents (e.g., phenothiazines), benzodiazepines, MAO inhibitors, narcotic analgesics (e.g., meperidine), nitrates and nitrites, sympathomimetic agents, tricyclic antidepressants, and other drugs having anticholinergic activity.

Anticholinergics antagonize the effects of antiglaucoma agents. Anticholinergic drugs in the presence of increased intraocular pressure may be hazardous when taken concurrently with agents such as corticosteroids. (See also CONTRAINDICATIONS.)

Anticholinergic agents may affect gastrointestinal absorption of various drugs, such as slowly dissolving dosage forms of digoxin; increased serum digoxin concentration may result. Anticholinergic drugs may antagonize the effects of drugs that alter gastrointestinal motility, such as metoclopramide. Because antacids may interfere with the absorption of anticholinergic agents, simultaneous use of these drugs should be avoided. The inhibiting effects of anticholinergic drugs on gastric hydrochloric acid secretion are antagonized by agents used to treat achlorhydria and those used to test gastric secretion.

OVERDOSAGE

Signs and Symptoms

The signs and symptoms of overdosage are headache; nausea; vomiting; blurred vision; dilated pupils; hot, dry skin; dizziness; dryness of the mouth; difficulty in swallowing; and CNS stimulation. A curare-like action may occur (i.e., neuromuscular blockade leading to muscular weakness and possible paralysis).

A 37-year-old female reported numbness on the left side, cold fingertips, blurred vision, abdominal and flank pain, decreased appetite, dry mouth, and nervousness following ingestion of 320 mg daily (four 20 mg tablets QID) for four days. These events resolved after discontinuing the dicyclomine.

Oral LD ₅₀

The acute oral LD₅₀ of the drug is 625 mg/kg in mice.

Minimum Human Lethal Dose/Maximum Human Dose Recorded

The amount of drug in a single dose that is ordinarily associated with symptoms of overdosage or that is likely to be life-threatening, has not been defined. The maximum human oral dose recorded was 600 mg by mouth in a 10-month-old child and approximately 1500 mg in an adult, each of whom survived. In three of the infants who died following administration of dicyclomine hydrochloride (see WARNINGS), the blood concentrations of drug were 200, 220, and 505 ng/mL, respectively.

Dialysis

It is not know if BENTYL is dialyzable.

Treatment

Treatment should consist of gastric lavage, emetics, and activated charcoal. Sedatives (e.g., short-acting barbiturates, benzodiazepines) may be used for management of overt signs of excitement. If indicated, an appropriate parenteral cholinergic agent may be used as an antidote.

CONTRAINDICATIONS

1. Obstructive uropathy
2. Obstructive disease of the gastrointestinal tract
3. Severe ulcerative colitis (See PRECAUTIONS)
4. Reflux esophagitis
5. Unstable cardiovascular status in acute hemorrhage
6. Glaucoma
7. Myasthenia gravis
8. Evidence of prior hypersensitivity to dicyclomine hydrochloride or other ingredients of these formulations
9. Infants less than 6 months of age (See WARNINGS and PRECAUTIONS: Information for Patients.)
10. Nursing Mothers (See WARNINGS and PRECAUTIONS: Information for Patients.)