Co-phenotrope

Comprehensive information about Lomotil and allied drugs is under the article Diphenoxylate.

The drug combination diphenoxylate/atropine (trade name Lomotil) is a popular oral anti-diarrheal in the United States, manufactured by Pfizer. Its UK BAN generic name is co-phenotrope.

Its active ingredients are diphenoxylate and atropine. Diphenoxylate is anti-diarrheal and atropine is anticholinergic. A subtherapeutic amount of atropine sulfate is present to discourage deliberate overdosage. Atropine has no anti-diarrheal properties, but will cause tachycardia when overused. The medication diphenoxylate works by slowing down the movement of the intestines. In some cases Lomotil has been shown to ease symptoms of opiate/opioid withdrawal.

The inactive ingredients of Lomotil (as a liquid; it comes in pill form as well) are cherry flavor, citric acid, ethyl alcohol 15%, FD&C Yellow No. 6, glycerin, sodium phosphate, sorbitol, and water.

Other trade names for the same therapeutic combination are Lofene, Logen, Lomanate and Lonox, among others. In other countries, Lomotil may have other names.

In the United States, Lomotil is classified as a Schedule V controlled substance by federal law, and is available only for a medical purpose.^[1]

Contraindications

Absolute contraindications for Lomotil are:

• Allergy to diphenoxylate or atropine
• Diarrhea associated with pseudomembranous enterocolitis, diarrhea caused by antibiotic treatment, or diarrhea caused by enterotoxin-producing bacteria.
• Presence of jaundice

Interactions

Interactions with other drugs:

• Antidepressants (e.g. Elavil, Prozac)^[2]
• Monoamine oxidase inhibitors (e.g. Nardil, Parnate)
• Opioid analgesics^[2]
• Sedatives (e.g. Ambien, Sonata)^[2]

Diarrhea that is caused by some antibiotics such as cefaclor, erythromycin or tetracycline can worsen with Lomotil.

Safety

The drug combination is generally safe in short-term use and with recommended dosage. In doses used for the treatment of diarrhea, whether acute or chronic, diphenoxylate has not produced addiction.

Lomotil may cause several side-effects, such as dry mouth, headache, constipation and blurred vision. Since it may also cause drowsiness or dizziness, Lomotil should not be used by motorists, operators of hazardous machinery, etc. It is not recommended for children under two years of age.

Toxicity

Lomotil may cause serious health problems when overdosed. Signs and symptoms of adverse effects may include any or several of the following: convulsions, respiratory depression (slow or stopped breathing), dilated eye pupils, nystagmus (rapid side-to-side eye movements), erythema (flushed skin), gastrointestinal constipation, nausea, vomiting, paralytic ileus, tachycardia (rapid pulse), drowsiness and hallucinations. Symptoms of toxicity may take up to 12 hours to appear.

Treatment of Lomotil overdose must be initiated immediately after diagnosis and may include the following: ingestion of activated charcoal, laxative and a counteracting medication (narcotic antagonist).

References