Opioids antidiarrheal action

These dm may produce withdrawal symptoms in those physically dependent on the narcotics. The patient must not have taken any opiate for the last 7 to 10 days. Naloxone may prevent die action of opioid antidiarrheals, antitussives, and analgesics. This drug is used cautiously during lactation. 

Diphenoxylate + Atropine (Lomotil, Lonox) [C V] [Opioid Antidiarrheal] Uses D Action Constipating m CTidine congener, X GI motihty Dose Adults. Initial, 5 mg PO tid—qid until controlled, then 2.5-5 mg PO bid 20 mg/d max Peds >2 y. 0.3-0.4 mg/kg/24 h (of diphenoxylate) bid-qid, 10 mg/d max Caution [C, +] Contra Obstructive jaundice, D d/t bacterial Infxn children <2 y Disp Tabs, Liq SE Drowsiness, dizziness, xCTostomia, blurred vision, urinary retention, constipation Interactions T Effects W/ CNS depressants, opioids, EtOH, T risk HTN crisis W7 MAOIs EMS Monitor for Sxs of electrolyte disturbances and hypovolemia d/t D OD May cause Szs, hypotension, and anticholinergic effects (xerostomia [dry mouth], urine retention, flushed skin) activated charcoal may be effective for OD... 

You are on your way to take an examination and you suddenly get an attack of diarrhea. If you stop at a nearby drugstore for an over-the-counter opioid with antidiarrheal action, you will be asking for... 

Kappa receptor activation does not appear to be responsible for dependence, euphoria, or effects on smooth muscle. Increases in cerebral blood flow and (possibly) increased intracranial pressure result from the respiratory depressant actions of opioid analgesics. The latter effects are due to increased arterial PrOj, which results from mu receptor inhibition of the medullary respiratory center. However, the activation of kappa receptors contributes to analgesia at the spinal level and is probably responsible for sedative actions of the opioids. The answer is (D). Codeine and possibly nalbuphine could decrease gastrointestinal peristalsis but not without marked side effects (and a prescription). Dextromethorphan is a cough suppressant. The other two drugs listed are opioids with antidiarrheal actions. Diphenoxylate is not available over-the-counter since it is a constituent of a proprietary combination that includes atropine sulfate (Lomotil). Loperamide is available over-the-counter. The answer is (D). 

Opioids. Activation of opioid receptors in the enteric nerve plexus results in inhibition of propulsive motor activity and enhancement of segmentation activity. This antidiarrheal effect was formerly induced by application of opium tincture (paregoric) containing morphine. Because of the CNS effects (sedation, respiratory depression, physical dependence), derivatives with peripheral actions have been developed. Whereas diphenoxylate can still produce clear CNS effects, loperamide does not Lullmann, Color Atlas of Pharmacology... 

The antidiarrheal activity of codeine results from two actions. First, there is a decrease in the propulsive contractile activity of the small and large intestines, which delays the forward movement of the contents of the intestines. Second, codeine causes an increase in the absorption of water from the intestinal contents. These gastrointestinal effects are mediated by specific opioid receptors in the gut (as we will see in... 

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. 

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