Example: After is administration of 500 mg procainamide (PA) to a patient, the AUC of PA was 12.5 mg-hr/L while the AUC for the major metabolite N-acetylprocainamide (NAPA) was 10.6 mg-hr/L. When a single iv dose of 250 mg NAPA was administered to the same patient, NAPA AUC was 17.0 mg-hr/L. Calculate the fraction of PA dose metabolized to NAPA.
The metabolite AUC is dependent
on the amount of the metabolite
formed and CLT(m).
CLT(m) can be determined after
administration of the preformed
metabolite
This means that after PA administration 31% of the dose is metabolized to NAPA
