Pyrimethamine

Definition

Pyrimethamine is an antiparasitic drug primarily used to treat toxoplasmosis and malaria. It works by inhibiting dihydrofolate reductase, an enzyme necessary for the replication of protozoal DNA.

5 Must Know Facts For Your Next Test

1. Pyrimethamine is often combined with sulfadiazine to enhance its efficacy against Toxoplasma gondii.
2. The drug can cause side effects such as bone marrow suppression, which necessitates monitoring blood cell counts during treatment.
3. Pyrimethamine is classified as a folic acid antagonist because it disrupts the production of tetrahydrofolic acid in parasites.
4. It has been used both in prophylaxis and treatment of malaria, particularly for strains resistant to other antimalarial drugs.
5. Resistance to pyrimethamine can occur through mutations in the dihydrofolate reductase gene of the parasite.

Review Questions

• What enzyme does pyrimethamine inhibit, and why is this important?
• Why is pyrimethamine often combined with sulfadiazine in treating toxoplasmosis?
• What are common side effects associated with pyrimethamine?

Related terms

Toxoplasmosis: A parasitic infection caused by Toxoplasma gondii, often treated with pyrimethamine.

Dihydrofolate Reductase: An enzyme targeted by pyrimethamine to inhibit protozoal DNA synthesis.

Folic Acid Antagonist: A class of drugs that includes pyrimethamine, which interferes with folic acid metabolism in parasites.