In the metabolism of drugs, an individual can be classified in one of five categories (metabolism phenotype) for each gene, based on the activity of these pharmacogenomic proteins as defined by the Clinical Pharmacogenetics Implementation Consortium (CPIC):

Normal (formerly extensive metabolizer) (NM/EM)

• Fully functional enzyme activity.

Intermediate metabolizer (IM)

• Decreased enzyme activity (activity between normal and poor metabolizer).

Poor Metabolizer (PM)

• Little to no enzyme activity.

Rapid/Ultrarapid Metabolizer (UM)

• Increased enzyme activity compared to normal metabolizers.

By considering an individual’s genetics relative to drug metabolizing enzymes, targets, receptors and transporters, healthcare providers can now apply this information to prescribing for optimal drug therapy.