Monoamine oxidase with meperidine

Meperidine should not be combined with monoamine oxidase inhibitors because of the possibility of severe respiratory depression or excitation, delirium, hyperpyrexia, and convulsions. 

Meperidine Demerol 50-100 mg every 3 hours An effective pain reliever but potentially fatal if given in combination with antidepressants known as MAO (monoamine oxidase) inhibitors can also cause seizures... 

Adverse effects Large doses of meperidine cause tremors, muscle twitches, and rarely, convulsions. The drug differs from opioids in that in large doses it dilates the pupil and causes hyperactive reflexes. Severe hypotension can occur when the drug is administered postoperatively. When used with major neuroleptics, depression is greatly enhanced. Administration to patients taking monoamine oxidase inhibitors (see p. 123) can provoke severe reactions such as convulsions and hyperthermia. Meperidine can cause dependence, and can substitute for morphine or heroin in use by addicts. Cross-tolerance with the other opioids occurs. 

MPPP, also referred to as meperidine, is a synthetic analgesic with morphinelike properties. If the chemical reaction used to synthesize MPPP is not carefully regulated, a toxic by-product is also produced. When this latter molecule, MPTP, is inadvertently consumed, it is converted in the brain to MPP+, a neurotoxic agent, in an oxidation reaction catalyzed by monoamine oxidase (see p. 517). 

Diphenoxylate is an opiate (schedule V) with antidiarrheal properties. It is usually dispensed with atropine and sold as Lomotil. The atropine is added to discourage the abuse of diphenoxylate by narcotic addicts who are tolerant to massive doses of narcotic but not to the CNS stimulant effects of atropine. Diphenoxylate shonld be used cautiously in patients with obstructive jaundice because of its potential for hepatic coma, and in patients with diarrhea cansed by pseudomembranous colitis because of its potential for toxic megacolon. In addition, it should be used cautiously in the treatment of diarrhea caused by poisoning or by infection by Shigella, Salmonella, and some strains of E. coli because expulsion of intestinal contents may be a protective mechanism. Diphenoxylate should be used with extreme caution in patients with impaired hepatic function, cirrhosis, advanced hepatorenal disease, or abnormal liver function test results, because the drug may precipitate hepatic coma. Because diphenoxylate is structurally related to meperidine, it may cause hypertension when combined with monoamine oxidase inhibitors. As a narcotic, it will augment the CNS depressant effects of alcohol, hypnotic-sedatives, and numerous other drugs, such as neuroleptics or antidepressants that cause sedation. 

Monoamine oxidase inhibitors (MAOIs) must be administered with utmost caution in conjunction with narcotic analgesics by virtue of their extremely intensified activity, for instance patients treated with MAOIs when treated with meperidine give rise to such a severe reaction that may sometimes even prove to be fatal. 

Meperidine has a strong adverse reaction when given to patients receiving a monoamine oxidase inhibitor. This drug interaction has been seen recently in patients with Parkinson s disease taking the monoamine oxidase-selective inhibitor selegiline (Eldepryl). 

The monoamine oxidase inhibitors (MAOIs) work through augmented activity of dopamine, as monoamine oxidase normally degrades norepinephrine and serotonin. The MAOIs are rarely used clinically due to their adverse effects, notably orthostatic hypotension, peripheral edema, myoclonic jerks, weakness, and insomnia. Hypertensive crisis can result when combined with sympathomimetics, including over-the-counter products such as ephe-drine and pseudoephedrine. Further, MAOIs are known to contribute to the serotonin syndrome and use of meperidine must be avoided in such patients. Patients on MAOI need to restrict tyramine-rich foods, as well [1,2]. 

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