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In view of the small amount of atropine present (0.025 mg/tablet), such effects such as dryness of the skin and mucous membranes, flushing, hyperthermia, tachycardia and urinary retention are very unlikely to occur, except perhaps in children.

Many of the adverse effects reported during clinical investigation of MOTOFEN (difenoxin and atropine) ® are difficult to distinguish from symptoms associated with the diarrheal syndrome. However, the following events were reported at the stated frequencies:

Gastrointestinal

Nausea, 1 in 15 patients; vomiting, 1 in 30 patients; dry mouth, 1 in 30 patients; epigastric distress, 1 in 100 patients; and constipation, 1 in 300 patients.

Central Nervous System

Dizziness and lightheadedness, 1 in 20 patients; drowsiness, 1 in 25 patients; and headache, 1 in 40 patients; tiredness, nervousness, insomnia and confusion ranged from 1 in 200 to 1 in 600 patients.

Other less frequent reactions

Burning eyes and blurred vision occurred in a few cases.

The following adverse reactions have been reported in patients receiving chemically-related drugs: numbness of extremities, euphoria, depression, sedation, anaphylaxis, angioneurotic edema, urticaria, swelling of the gums, pruritus, toxic megacolon, paralytic ileus, pancreatitis, and anorexia.

THIS MEDICATION SHOULD BE KEPT IN A CHILD-RESISTANT CONTAINER AND OUT OF THE REACH OF CHILDREN SINCE AN OVERDOSAGE MAY RESULT IN SEVERE RESPIRATORY DEPRESSION AND COMA, POSSIBLY LEADING TO PERMANENT BRAIN DAMAGE OR DEATH.

Drug Abuse And Dependence

MOTOFEN (difenoxin and atropine) ® (difenoxin hydrochloride with atropine sulfate) tablets are a Schedule IV controlled substance.

Addiction to (dependence on) difenoxin hydrochloride is theoretically possible at high dosage. Therefore, the recommended dosage should not be exceeded. Because of the structural and pharmacological similarities of difenoxin hydrochloride to drugs with a definite addiction potential, MOTOFEN (difenoxin and atropine) ® should be administered with considerable caution to patients who are receiving addicting drugs, to individuals known to be addiction prone, or to those in whom histories suggest may increase the dosage on their own initiative.

Since the chemical structure of difenoxin hydrochloride is similar to meperidine hydrochloride, the concurrent use of MOTOFEN (difenoxin and atropine) ® with monoamine oxidase inhibitors may, in theory, precipitate a hypertensive crisis.

MOTOFEN (difenoxin and atropine) ® may potentiate the action of barbiturates, tranquilizers, narcotics, and alcohol. When these medications are used concomitantly with MOTOFEN (difenoxin and atropine) ®, the patient should be closely monitored.

Diphenoxylate hydrochloride, from which the principal active metabolite difenoxin is derived, was found to inhibit the hepatic microsomal enzyme system at a dose of 2 mg/kg/day in studies conducted with male rats. Therefore, difenoxin has the potential to prolong the biological half-lives of drugs for which the rate of elimination is dependent on the microsomal drug metabolizing enzyme system.

Last reviewed on RxList: 5/12/2009
This monograph has been modified to include the generic and brand name in many instances.