Phenothiazine metabolites in plasma (total, including primary and secondary metabolites)

Why This Test Is Done

Your healthcare provider may order this test if you’re taking phenothiazine medications, such as prochlorperazine or promethazine. It helps ensure the drug is at an appropriate level to manage symptoms while minimizing side effects. This is particularly important if you’re taking these drugs long-term or at high doses.

What to Expect Before the Test

No special preparation is needed. You may have a blood draw from a vein in your arm, similar to other routine blood tests. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Results are not typically provided as a single number but rather as a qualitative or semi-quantitative assessment of metabolite presence. High levels may indicate overdose or improper metabolism, while low levels could suggest insufficient drug concentration. Your provider will interpret results in the context of your symptoms and medication regimen.

Possible Side Effects or Risks

The most common risk is mild discomfort at the needle site, such as bruising or slight pain. Rarely, blood tests can cause allergic reactions or infections, though these are uncommon. If you experience severe pain, swelling, or signs of infection (like fever), contact your provider immediately.