Decarboxylation, reduction and hydrolysis can yield active metabolites from the parent drug. Major therapeutic indications
and metabolic routes of these drugs are reviewed.
Changes in the logP values (determined and calculated) from the parent drug to the active metabolite show certain characteristics in comparison
to other phase I metabolic alterations. Metabolic decarboxylation of parent drug is commonly associated with increase in lipophilicity.
However, in some cases, decarboxylation may cause a reduction in lipophilicity. Ester hydrolysis generally unmasks either the
polar carboxylic or hydroxyl group with the outcome of an increase in hydrophilicity. On the contrary, hydrolysis of phosphate ester
means a huge increase in the lipophilic character of the drug, as the highly polar phosphate group is removed.