Which of the following statements is not true?

Though it may not be required, TDM should still be used to confirm adequate dosing.

Genotyping does not make TDM redundant.

A PM will metabolize the drug more slowly and therefore will need lower doses. CYP2D6 metabolizes many different drugs; it is not associated with just one class of drugs. Anytime a drug is taken that competes for the same metabolizing enzyme as another drug, there is potential for the concentrations of both drugs to be increased.

A patient has been characterized as a CYP2D6 poor metabolizer (PM) after genotyping.

Which of the following statements is not true?
A . The patient will likely need lower doses of CYP2D6-metabolized drugs.
B. The patient is less likely to require therapeutic drug monitoring (TDM) since the genotype is known.
C. CYP2D6 metabolizes many drugs, and so attention must be given to the doses of drugs from different classes.

Answer: B