diphenoxylate hydrochloride and atropine sulfate (co-phenotrope (UK))
Pharmacologic class: Anticholinergic, meperidine congener
Therapeutic class: Antidiarrheal
Controlled substance schedule V
Pregnancy risk category C
Action
Acts on smooth muscle of GI tract by decreasing peristalsis, which inhibits motility. (Small amount of atropine is added to reduce abuse potential.)
Availability
Liquid: 2.5 mg diphenoxylate and 0.025 mg atropine/5 ml
Tablets: 2.5 mg diphenoxylate and 0.025 mg atropine
Indications and dosages
➣ Diarrhea
Adults: Initially, 5 mg P.O. three to four times daily, then 5 mg/day as needed (not to exceed 20 mg/day). Decrease dosage when desired response occurs.
Children: Initially, 0.3 to 0.4 mg/kg P.O. (liquid only) daily in four divided doses. Decrease dosage when desired response occurs.
Dosage adjustment
• Elderly patients
Contraindications
• Hypersensitivity to drug
• Obstructive jaundice
• Diarrhea associated with pseudomembranous colitis or enterotoxinproducing bacteria
• Angle-closure glaucoma
• Concurrent MAO inhibitor use
• Children younger than age 2
Precautions
Use cautiously in:
• inflammatory bowel disease; prostatic hypertrophy; severe hepatic disease (use with extreme caution)
• concurrent use of drugs that cause physical dependence; history of physical drug dependence
• elderly patients
• pregnant or breastfeeding patients
• children (safety not established in children younger than age 12).
Administration
☞ Don't confuse brand name Lomotil with Lamictal (an anticonvulsant). Serious errors have been reported.
• Withhold drug if patient has severe fluid or electrolyte imbalance.
• Administer with food if GI upset occurs.
☞ Don't give within 14 days of MAO inhibitors.
Adverse reactions
CNS: dizziness, confusion, drowsiness, headache, insomnia, nervousness
CV: tachycardia
EENT: blurred vision, dry eyes
GI: nausea, vomiting, constipation, epigastric distress, ileus, dry mouth
GU: urinary retention
Skin: flushing
Interactions
Drug-drug. CNS depressants (including antihistamines, sedative-hypnotics, opioids): increased CNS depression
Anticholinergic-like drugs (including tricyclic antidepressants, disopyramide): increased anticholinergic effects
MAO inhibitors: hypertensive crisis
Drug-diagnostic tests. Amylase: increased level
Drug-herbs. Angel's trumpet, jimsonweed, scopolia: increased anticholinergic effects
Drug-behaviors. Alcohol use: increased CNS depression
Patient monitoring
☞ Assess for and report abdominal distention and signs or symptoms of decreased peristalsis.
• Watch for signs and symptoms of dehydration.
• Assess frequency and consistency of bowel movements.
Patient teaching
• Instruct patient to report persistent diarrhea.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• Tell patient that prolonged use may lead to dependence.
• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.