Metoclopramide Opioids

DOMPERIDONE, METOCLOPRAMIDE OPIOIDS 1. i efficacy of domperidone on gut motility by opioids 2. Metodopramide T speed of onset and effect of oral morphine 1. Antagonist effect 2. Uncertain metodopramide may promote the absorption of morphine by increasing gastric emptying 1. Caution with co-administration 2. Be aware that the effects of oral morphine are T... 

Etomidate, maprotiline, metoclopramide, opioids (intrathecally), physostigmine... 

B. Two medicines, ipecac and apomorphine, induce vomiting. Metoclopramide is a prokinetic with antiemetic properties and therefore would have the opposite of the desired effect. Morphine is an opioid with analgesic and sedating properties. Promethazine and ondansetron are also antiemetics, not emetics. 

Drugs and chemicals are known to cause activated interaction. The depressant action of opioid drugs is enhanced by drugs acting on the central nervous system (CNS) such as alcohol, anesthetics, anxiolytics, hypnotics, tricyclic antidepressants, and antipsychotics. Concomitant administration of opioid analgesics and monoamine oxidase inhibitors (MAOIs) should be avoided, or extra care should be taken if such a therapy is inevitable. Fatal reactions are reported when treated along with selegiline. Interactions also are reported with cyclizine, cimetidine, mexiletine, cisapride, metoclopramide, or domperidone. 

Metoclopramide increases the rate of absorption of oral morphine and increases its rate of onset and sedative effects. However, opioids may antagonise the effects of metoclopramide on gastric emptying. The use of droperidol with opioids can be beneficial, but an increase in sedation appears to occur. 

Metoclopramide increases the rate of gastric emptying so that the rate of morphine absorption from the small intestine is increased. An alternative idea is that both drugs act additively on opiate receptors to increase sedation. Droperidol may also enhance adverse effects such as sedation, and in some cases respiratory depression, possibly through opioid and other receptor sites in the CNS. In one case the respiratory depression was not reversed by naloxone, suggesting that the droperidol was at least partially if not completely responsible. ... 

Morphine appears to antagonise the effects of metoclopramide on gastric emptying. As a reduction in gastric motility occurs with all opioids they would all be expected to interact with metoclopramide, and other motility stimulants such as domperidone. However, these drugs are commonly used together and the clinical significance of such effects is not clear. Consider also Opioids + Antiemetics Ondansetron , below. 

McNeill Ml, Ho ET, Kenny GNC. Effect of i.v. metoclopramide on gastric emptying after opioid premedication. BrJAnaes i (1990) 64,450-2. 

A study in 8 healthy subjects found that a single 600-microgram dose of intravenous atropine reduced the rate of absorption of a single 400-mg oral dose of mexiletine, but the mexiletine AUC remained unaffected. Intravenous metoclopramide 10 mg hastened the absorption of mexiletine but similarly did not affect the AUC. Metoclopramide tended to reverse the effect of diamorphine on plasma mexiletine levels in one clinical trial (see also Mexiletine + Opioids , p.268). 

For the treatment of nausea and vomiting ondansetron or metoclopramide is often useful. For management of constipation one should consider that tolerance does not usually develop for the constipating effects of opioids. Laxatives and/or stool softeners should be used prophylactically from the beginning of opioid therapy. Agents that increase gastrointestinal propulsion should not be used as it may increase the risk of bowel perforation, if the patient has ileus and impacted stool. 

---