Opioid-related drugs

Opioid-related drugs

Opioid-related drugs decrease peristalsis (involuntary, progres-sive, wavelike intestinal movement that pushes fecal matter along) in the intestines and include:

• diphenoxylate with atropine

• loperamide.

Pharmacokinetics

The combination drug diphenoxylate with atropine is readily absorbed from the GI tract. However, loperamide isn’t absorbed well after oral administration.

Distribution, metabolism, and excretion

Both drugs are distributed in serum, metabolized in the liver, and excreted primarily in stool. Diphenoxylate with atropine is metabolized to difenoxin, its biologically active major metabolite.

Pharmacodynamics

Diphenoxylate with atropine and loperamide slow GI motility bydepressing peristalsis in the large and small intestines. Thesedrugs also decrease expulsive contractions throughout the colon.

Pharmacotherapeutics

Diphenoxylate with atropine and loperamide are used to treat acute, nonspecific diarrhea. Loperamide is used to treat chronic diarrhea.

Drug interactions

Diphenoxylate with atropine and loperamide may enhance the depressant effects of barbiturates, alcohol, opioids, tranquilizers,and sedatives. (See Adverse reactions to opioid-related drugs.)