Cytochrome P450 2C19 Phenotyping (Metabolizer Typing)

Why This Test Is Done

Doctors may order this test if you’re prescribed medications that rely on CYP2C19 for metabolism, such as clopidogrel (Plavix) for blood thinning or escitalopram (Lexapro) for depression. It helps avoid side effects or reduced effectiveness by matching the right dose to your genetic profile.

How the Test Works

The test analyzes a small sample of your blood (serum or plasma) to assess how efficiently your body processes specific drugs. It doesn’t measure drug levels directly but evaluates your genetic capacity to metabolize them.

What to Expect Before the Test

No special preparation is needed. Bring a list of all medications (including over-the-counter and supplements) you take, as some may affect results. Avoid alcohol for 24 hours before testing, as it can influence enzyme activity.

Test Results and Interpretation

Results are categorized as *extensive metabolizers*, *intermediate metabolizers*, or *poor metabolizers*—indicating how quickly your body breaks down drugs. Your doctor will use these findings to adjust your medication plan.