CYP450 Liver Enzyme and its effects on Methadone.

[drscience]

Hi, I am a Methadone patient, and just took some phenobarbital after reading extensively on the chemical.

What I failed to understand was Phenobarbs effect on CYP450 and if it wlll make me metabolize my Methadone faster.

Anyone have any info on this?

Thanks in advance,

Mike

 

[AromaticNitrogen]

Phenobarb tends to act as an inducer of different cyp enzymes, some of which are responsible for metabolism of methadone. It could decrease the AUC plasma concentration of methadone when coadministered. Basically yes, phenobarbital will generally increase the rate of methadone metabolism.

 

[Erikmen]

Which is not good as Methadone should be in the bloodstream for a longer period. That could perhaps anticipate some of the w/d symptoms.

 

[aced126]

Acute barbiturate exposure does not upregulate P450 enzymes. If you rarely take barbiturates this shouldn't be a problem.

Chronic barbiturate exposure upregulates ALA synthase, resulting in increased poryphrin synthesis, which results in more heme synthesis and thus more P450 enzymes (which incorporate a heme group in their structure). CYP 1A2, 2C9, 2C19 and 3A4 are induced, of which 3A4 is one of the enzymes responsible for metabolising methadone.