usmleasr
Forum Guru
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can anyone describe, drug interactions of ethanol, in acute and chronic settings?
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| dxtxpx
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http://www.bnf.org/bnf/bnf/current/doc/41001i20.h...
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| usmleasr
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ya..i saw in this link that , drug..chlorpropamide has disulfiram like effect..actually in acute setting alcohol occupies cyt-p450 and reduces metabolism of drugs...but in chronic alcohol user..enzyme is induced and drugs are metabolized fast...is that correct?
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| asmi
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acute ethanol .use....inhibitor of cyto P450.
chronic ethanol use........inducer of cyto P450.
it follows zero order kinetics
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| asmi
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this artical will definately help us..
http://www.doctorniruprasad.com/Theguidforman.htm...
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| asmi
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Alcohol (Ethanol) and Drug Interactions
Alcohol is a brain (CNS) depressant, and therefore additive with other CNS depressants such as antihistamines, narcotics, Xanax, Valium, opiates.
Impairment can occur at significantly lower levels of blood alcohol levels due to this additive effect on the brain. For example: alcohol usage and concomitant ingestion of opiates.
Effects of alcohol on the liver via P450 enzyme causes reduced metabolism of other medications and therefore may increase the concentration of a given drug which is metabolized by this enzyme.
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| asmi
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one more ...
CYTOCHROME-P450 COMPLEX:
There are multiple isotypes.
CYT-P450-2 and CYT-P450-3A are responsible for the metabolism of most drugs.
CYT-P450-3A4 metabolizes many drugs in the GI-Tract, where it decreases the bioavailability of many orally absorbed drugs.
INDUCERS of CYT-P450 COMPLEX: Drugs that increase the production of Cytochrome-P450 enzymes.
ANTI-CONVULSANTS: Phenobarbitol, Phenytoin, Carbamazepine induce CYT-P450-3A4
Phenobarbitol, Phenytoin also induce CYT-P450-2B1
Polycyclic Aromatics (PAH): Induce CYT-P450-1A1
Glucocorticoids induce CYT-P450-3A4
Chronic Alcohol, Isoniazid induce CYT-P450-2E1. This is important as this drug activates some carcinogens such as Nitrosamines.
Chronic alcoholics have up-regulated many of their CYT-P450 enzymes.
INHIBITORS of CYT-P450 COMPLEX: Drugs that inhibit the production of Cytochrome-P450 enzymes.
Acute Alcohol suppresses many of the CYT-P450 enzymes, explaining some of the drug-interactions of acute alcohol use.
Erythromycin, Ketanazole inhibit CYT-P450-3A4.
Terfenadine (Seldane) is metabolized by CYT-P450-3A4, so the toxic unmetabolized form builds up in the presence of Erythromycin. The unmetabolized form is toxic and causes lethal arrhythmias. This is why Seldane was taken off the market.
Chloramphenicol, Cimetidine, Disulfiram also inhibit CYT-P450's.
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| usmleasr
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O.M.G(oh my god)
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