Question

1a.) Drug C goes through the cytochrome P450 enzyme. Drug D is anti-inducer of cytochrome P450. A patient has been using Drug C with good results. The patient has now started therapy with Drug D. What will happen to the concentrations of Drug C? (Choices: Increase, Decrease, Stay the same, Not enough info given)

1b.) Drug C goes through the cytochrome P450 enzyme. Drug D is an inhibitor of cytochrome P450. A patient has been using Drug D with good results. The patient has now started therapy with Drug D. What will happen to the concentration of Drug C? (Choices: Increase, Decrease, Stay the same, Not enough info given)

Answer 1

1.a. Drug C goes through the cytochrome P450 enzyme.

Drug D is anti-inducer of cytochrome P450.

If both the drugs are taken simultaneously the, Drug D will impart anti-inducer action or oposing or inhibiting action on the cytochrome P450 enzyme, hence will increase the concentrations of Drug C. It may cause the toxicity of drug C.

1.b. Drug C goes through the cytochrome P450 enzyme

Drug D is an inhibitor of cytochrome P450.

If both the drugs are taken simultaneously the, Drug D will decrease the methabolism of drug C as it inhibit the metabolizing enzyme cytochrome P450.

Hence the concentration of Drug C will increase.