Proper Administration of Lomotil (Diphenoxylate with Atropine)
Lomotil (diphenoxylate hydrochloride with atropine sulfate) should be administered at an initial dose of 4 mg (2 tablets) followed by 2 mg (1 tablet) after every loose stool, not exceeding 16 mg daily for adults with diarrhea. 1, 2
Dosage Guidelines for Adults
- Initial dose: 4 mg (2 tablets) 1
- Maintenance dose: 2 mg (1 tablet) after each loose stool 1
- Maximum daily dose: 16 mg (8 tablets) per day 1
- Allow sufficient time between doses (at least 2-4 hours) to avoid rebound constipation 1
- Continue until diarrhea resolves, then discontinue after a 12-hour diarrhea-free interval 1
Important Administration Considerations
- Lomotil requires a prescription, unlike loperamide which is available over-the-counter 3
- Lomotil is generally less effective than loperamide for acute diarrhea 1
- Intestinal transit is more prolonged by both diphenoxylate and atropine in Lomotil than by loperamide alone 1
- Lomotil may cause drowsiness or dizziness; patients should be cautioned about activities requiring mental alertness 2
- Avoid alcohol, barbiturates, and tranquilizers during Lomotil treatment due to potential interactions 2
Contraindications and Warnings
- NOT RECOMMENDED FOR CHILDREN UNDER 2 YEARS OF AGE due to risk of serious adverse effects 1, 2, 4
- Contraindicated in severe dysentery with high fever or blood in stool 1, 3
- Use with caution in patients with hepatic dysfunction as it may prolong the biological half-lives of other drugs 2
- May interact with MAO inhibitors 2
- Potentiation of action can occur with concomitant use of alcohol, barbiturates, and tranquilizers 2
Special Populations
- Pregnancy: Use only if benefits justify potential risks (Pregnancy Category C) 2
- Nursing mothers: Use with caution as metabolites may be secreted in breast milk 2
- Elderly: May require dose adjustment due to potential for increased sensitivity to side effects 2
Monitoring and Follow-up
- Monitor for signs of dehydration and electrolyte imbalance, especially in moderate to severe diarrhea 1
- If diarrhea persists for more than 48 hours despite treatment, consider alternative therapy or additional diagnostic evaluation 1
- If symptoms worsen (fever, bloody stools, severe abdominal pain), discontinue Lomotil and seek medical attention 1
Clinical Pearls
- For traveler's diarrhea, Lomotil is less preferred than loperamide due to its lower efficacy and higher side effect profile 1
- In cancer treatment-induced diarrhea, Lomotil can be used but may require addition of other agents if symptoms persist 1
- Accidental overdose, particularly in children, can cause respiratory depression that may respond to naloxone 4