Class: Antidiarrheal. C-V
Dosage Forms. Tablet: Diphenoxylate 2.5 mg with atropine 0.025 mg; Solution: Diphenoxylate 2.5 mg/5 mL with atropine 0.025 mg/5 mL
Common FDA Label Indication, Dosing, and Titration.
1. Diarrhea: Children 2 y and older, 0.3 mg-0.4 mg/kg/d (diphenoxylate) po qid to max of 20 mg/d (diphenoxylate); Adults, 2 tablets po qid until diarrhea resolves, then reduce dose to maintain efficacy, to max of 20 mg/d (diphenoxylate)
Off-Label Uses. None
MOA. Diphenoxylate is a synthetic meperidine congener without analgesic activity that slows GI motility. Because high doses of diphenoxylate (40-60 mg) cause systemic opioid activity, atropine is added in subtherapeutic amounts to decrease abuse potential.
Drug Characteristics: Diphenoxylate/Atropine
Medication Safety Issues: Diphenoxylate/Atropine
Drug Interactions: Diphenoxylate/Atropine
Adverse Reactions: Diphenoxylate/Atropine
Efficacy Monitoring Parameters. Frequency and volume of bowel movements; body temperature; blood in stool.
Toxicity Monitoring Parameters. Monitor for signs of atropine toxicity and for abdominal distention.
Key Patient Counseling Points. This drug can cause dry mouth, blurred vision, drowsiness, or dizziness; use caution while driving or performing other tasks requiring alertness, coordination, or physical dexterity. Avoid alcohol and other CNS depressants. Seek medical attention if diarrhea persists or if fever, palpitations, or abdominal distention occurs. Ensure max daily dose is not exceeded to avoid toxicity.
Clinical Pearls. Signs of atropine toxicity often referred to as “dry as a bone, hot as a hare, red as a beet, blind as a bat, mad as a hatter.” Higher than usual doses may be administered to patients receiving irinotecan.