barbiturates contraindicated in porphyria patients - USMLE Forums
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Old 07-14-2011
yasirsattar75's Avatar
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Biochemistry barbiturates contraindicated in porphyria patients

barbiturate indduces p450 enzyme system and increases the formation of heme? and as in porphyrias there is enzyme deficiency such as urobillinogen decarboxylase and porphobillinogen decarboxylase etc .. so more heme formation provokes porphyrias .. can anyone explain more plz ....
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Old 07-14-2011
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Ya sure it's cuz the p450 enzymes contain heme in their structure.. So if u have a deficiency in one of the enzymes of the heme pathway, and u take a barbiturate it will increase sythesis of p450 which will result in accumulation of the substrates that come before the enzmes deficient in the heme pathway..
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