Isozymes responsible for metabolism

Failure of contraceptive therapy and breakthrough bleeding have been noted repeatedly in patients concurrently taking various enzyme-inducing anticonvulsant drugs (305,314). These include phenytoin, primidone, ethosux-imide, phenobarbital, and carbamazepine. The specific isozyme responsible for metabolic 2-hydroxylation of ethinylestradiol is CYP3A4, which is induced by... 

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