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diphenoxylate/atropine (dye-fen-ox-i-late/a-troe-peen)

Logen, Lomanate, Lomotil, Lonox

difenoxin/atropine (dye-fen-ox-in/a-troe-peen)



Therapeutic: antidiarrheals

Pharmacologic: anticholinergics

Schedule V (diphenoxylate/atropine), IV (difenoxin/atropine)


Adjunctive therapy in the treatment of diarrhea.


Inhibits excess GI motility. Structurally related to opioid analgesics but has no analgesic properties. Atropine added to discourage abuse. Therapeutic Effects: Decreased GI motility with subsequent decrease in diarrhea.

Adverse Reactions/Side Effects

CNS: dizziness, confusion, drowsiness, headache, insomnia, nervousness. EENT: blurred vision, dry eyes. CV: tachycardia. GI: constipation, dry mouth, epigastric distress, ileus, nausea, vomiting. GU: urinary retention. Derm: flushing.


Examination and Evaluation

  • Monitor improvements in GI symptoms (decreased diarrhea) to help document whether drug therapy is successful.

  • Assess dizziness that might affect gait, balance, and other functional activities (See Appendix C). Report balance problems and functional limitations to the physician, and caution the patient and family/caregivers to guard against falls and trauma.

  • Monitor other CNS side effects such as confusion, drowsiness, blurred vision, headache, nervousness, or insomnia. Report severe or prolonged CNS symptoms to the physician.

  • Assess heart rate, ECG, and heart sounds, especially during exercise (See Appendices G, H). Report increased heart rate (tachycardia) or symptoms of other arrhythmias such as palpitations, chest discomfort, shortness of breath, fainting, and fatigue/weakness.


  • Because of the tachycardia, use caution during aerobic exercise and other forms of therapeutic exercise. Assess exercise tolerance frequently (blood pressure, heart rate, fatigue levels), and terminate exercise immediately if any untoward responses occur (See Appendix L).

Patient/Client-Related Instruction

  • Advise patient to avoid alcohol and foods that may increase GI irritation and diarrhea.

  • Instruct patient to report other bothersome side effects such as severe or prolonged urinary retention, skin redness/warmth, or GI problems (constipation, nausea, vomiting, heartburn, dry mouth).


Absorption: Well absorbed from the GI tract.

Distribution: Enters breast milk.

Metabolism and Excretion: Diphenoxylate—mostly metabolized by the liver with some conversion to an active antidiarrheal compound (difenoxin). Difenoxin—metabolized by the liver. Minimal excretion in urine.

Half-life: Diphenoxylate—2.5 hr; difenoxin—4.5 hr.

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TIME/ACTION PROFILE (antidiarrheal action)

Difenoxin-PO 45–60 min 2 hr 3–4 hr
Diphenoxylate-PO 45–60 min 2 hr 3–4 hr


Contraindicated in: Hypersensitivity; Severe liver disease; Infectious diarrhea (due to Escherichia coli, Salmonella, or Shigella); Diarrhea associated with pseudomembranous colitis; Dehydrated patients; Angle-closure glaucoma; Children <2 yr; Known alcohol intolerance (some liquid diphenoxylate/atropine products only).


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