Question 1

Up to 21% of Asians are ultra-rapid 2D6 metabolizers, leading to:

A need to monitor drugs metabolized by 2D6 for toxicity
Increased dosages needed of drugs metabolized by 2D6, such as the selective
serotonin reuptake inhibitors
Decreased conversion of codeine to morphine by CYP 2D6
The need for lowered dosages of drugs, such as beta blockers

Question 2

Rifampin is a nonspecific CYP450 inducer that may:

Lead to toxic levels of rifampin and must be monitored closely
Cause toxic levels of drugs, such as oral contraceptives, when coadministered
Induce the metabolism of drugs, such as oral contraceptives, leading to therapeutic
failure
Cause nonspecific changes in drug metabolism

Question 3

Inhibition of P-glycoprotein by a drug such as quinidine may lead to:

Decreased therapeutic levels of quinidine
Increased therapeutic levels of quinidine
Decreased levels of a coadministered drug, such as digoxin, that requires P-glycoprotein for absorption and elimination
Increased levels of a coadministered drug, such as digoxin, that requires P-glycoprotein for absorption and elimination