Genetic variants that alter drug metabolism

Regarding genetic variants that alter drug metabolism. Which of the following statements is true? a. All the statements are true b. Drugs with a narrow therapeutic index, small increases in drug levels can lead to toxicity or small decreases in drug levels can lead to failure of drug therapy c. Drugs with a high therapeutic index such as warfarin is not a concern since it is not inactivated by CYP2C9 d. Drugs with a high therapeutic index, altered rates of metabolism will have significant effects on clinical outcomes When administering a drug, which of the following is not necessarily as important to determine the response of a drug? A. timing of administration B. Dosage C. Route D. Frequency