Studying the pharmacokinetics of the metabolites is important because some metabolites possess pharmacological activities similar to those of the parent drug and other metabolites have serious adverse effects.
a- Examples of metabolites that are pharmacologically active:
N-acetylprocainamide (Has antiarrhythmic effect)
b- Examples of metabolites that have toxic effects:
Carbamazepine epoxide (Has serious adverse effects)
The metabolite plasma concentration can be higher or lower than the parent drug concentration depending on the pharmacokinetic parameters of the drug, and the metabolite. So, it is important to determine how the change in each pharmacokinetic parameter will affect the drug/metabolite profiles in the body.
