Antidiarrheal agents opioids

The opioids contain natural and synthetic compounds that are medicinally used as analgesic, antidiarrheal, and antitussive agents. Opioids are CNS depressants and decrease blood pres-... 

Gastrointestinal effects Constipation occurs through decreased intestinal peristalsis, which is probably mediated by effects on opioid receptors in the enteric nervous system. This powerful action is the basis for the clinical use of these drugs as antidiarrheal agents. 

Observational studies Tincture of opium is a preparation of powdered opium, which contains morphine, codeine, papaverine, and alcohol. It is used as an antidiarrheal agent, to treat neonatal abstinence syndrome, in the management of pain, and traditionally for the management of opioid dependency in some Asian countries. In an open study, opium-dependent subjects were allocated to three different doses of tincture of opium twice a day 10 ml (6.66 mg morphine equivalents n = 13), 20 ml (13.3 mg morphine equivalents n = 8), and 30 ml (20 mg morphine equivalents n = 11) [1 j. In all the subjects tincture of opium effectively suppressed withdrawal symptoms without causing significant adverse effects. 

E. Antidiarrbeal Agents The most effective antidiarrheal drugs are the opioids and derivatives of opioids that have been selected for maximal antidiarrheal and minimal CNS effect. Of the latter group, the most important are diphenoxylate and loperamide, meperidine analogs with very weak analgesic effects. Difenoxin, the active metabolite of diphenoxylate, is also available as a prescription medication. Diphenoxylate is formulated with antimuscarinic alkaloids to reduce the already minimal likelihood of abuse loperamide is formulated alone and sold over the counter as such. 

A. Diphenoxylate is an opioid analog of meperidine. It is metabolized to difenoxin, which has fivefold the antidiarrheal activity of diphenoxylate. Both agents have opioid effects (see p 286) in overdose. 

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