The Cytochrome P450 2C19 enzyme (CYP2C19) plays a major role in drug metabolism. Different CYP2C19 variants are associated with varying activity levels. CYP2C19 genotyping screening assay tests for the presence of three specific CYP2C19 variants, which are associated with altered metabolism of drugs including clopidogrel. This assay can be useful in guiding drug selection and dosage adjustments for medications metabolised by this enzyme. It can help healthcare providers personalise treatment plans, optimize drug efficacy, and minimize the risk of adverse drug reactions based on an individual's genotype.
CYP2C19 genotyping involves identifying these genetic variations by analysing an individual's DNA sample, typically obtained through a blood or buccal swab. The genetic testing can determine a person's CYP2C19 genotype, which categorises individuals into different metabolizer phenotypes:
- Ultra-rapid metabolizers (UMs): UMs have genetic variations that lead to increased enzyme activity, resulting in faster drug metabolism. This phenotype is less common and may require dosage adjustments to achieve optimal therapeutic effects.
- Normal metabolizers (NMs): NMs have two functional copies of the CYP2C19 gene, resulting in normal enzyme activity. They can effectively metabolize drugs that are substrates of CYP2C19.
- Intermediate metabolizers (IMs): IMs have one functional and one non-functional copy of the CYP2C19 gene. Their enzyme activity may be reduced compared to normal metabolizers, but to a lesser extent than poor metabolizers.
- Poor metabolizers (PMs): These individuals have two non-functional copies of the CYP2C19 gene, resulting in significantly reduced or no enzyme activity. They may require dose adjustments or alternative medications, as certain drugs metabolized by CYP2C19 may accumulate in their system and lead to adverse effects or reduced efficacy.