doubt ? - spring09

[ArchivalUser]

does TMP-SMX have any effect on cytochrome p450 ...??

[ArchivalUser]

Sulphamethoxazole is extensively metabolized in vivo; its metabolic pathways involve acetylation, oxidation and glucuronidation

Oxidation takes place at different positions of the molecule: the unstable, reactive hydroxylamine metabolite is formed by oxidation of the N4 nitrogen atom while oxidation of the C5 methyl group leads to the stable 5-hydroxy metabolite.

Formation of both metabolites by cytochrome P450-mediated reaction was demonstrated in vitro using human liver microsomes. In vitro more sulphamethoxazole was N-hydroxylated than 5-hydroxylated.

You can follow this link... to see how deep they can go with it and why it is important to know.
http://jac.oxfordjournals.org/cgi/reprin...l_B/55.pdf

Good Luck

[ArchivalUser]

Sulphamethoxazole is extensively metabolized in vivo; its metabolic pathways involve acetylation, oxidation and glucuronidation

Oxidation takes place at different positions of the molecule: the unstable, reactive hydroxylamine metabolite is formed by oxidation of the N4 nitrogen atom while oxidation of the C5 methyl group leads to the stable 5-hydroxy metabolite.

Formation of both metabolites by cytochrome P450-mediated reaction was demonstrated in vitro using human liver microsomes. In vitro more sulphamethoxazole was N-hydroxylated than 5-hydroxylated.

You can follow this link... to see how deep they can go with it and why it is important to know.
http://jac.oxfordjournals.org/cgi/reprin...l_B/55.pdf

Good Luck

[ArchivalUser]

Hi spring09
TMP-SMX may act as an inhibitor of P450, thereby increasing the levels, and possibly toxicity, of other substrates, e.g. phenytoin.
Hope you're doing well

[ArchivalUser]

thanks !!
so if a pt. is on warfarin , and tmp-smx , we decrease the dose of warfarin ..right ..
it's in the fred exam .

[ArchivalUser]

Affirmative, as far as I am concerned