Professional and Linguistic Assessments Board (PLAB) Practice Exam

Disable ads (and more) with a membership for a one time $2.99 payment

Enhance your chances of passing the PLAB Exam. Study with our practice quizzes that feature multiple choice questions, comprehensive hints, and explanations. Prepare with confidence!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

Practice this question and more.

Which drug is noted as a P450 inducer?

Phenytoin
Diazepam
Metoprolol
Amiodarone

The correct answer is: Phenytoin

Phenytoin is recognized as a potent inducer of the cytochrome P450 enzyme system, particularly affecting CYP2C and CYP3A4 enzymes. As an anticonvulsant medication, it increases the metabolic activity of other drugs that are substrates for these enzymes, thereby reducing their plasma concentrations and effectiveness. This induction can lead to interactions where the efficacy of other medications decreases, necessitating dosage adjustments. In contrast, diazepam, metoprolol, and amiodarone primarily do not induce the P450 enzymes. Diazepam is a benzodiazepine metabolized mainly through conjugation and does not significantly induce P450 enzymes. Metoprolol, a beta-blocker, is metabolized by CYP2D6 but is not an inducer of the P450 system. Amiodarone, while it has a complex profile affecting various drug metabolizing enzymes, acts mainly as an inhibitor rather than an inducer of the P450 system. Therefore, phenytoin's role as a P450 inducer is the reason it stands out as the correct choice in this context.