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Pyrimethamine (PYR)
Pyrimethamine inhibits dihydrofolate reductase, blocking the synthesis of tetrahydrofolate and thereby preventing DNA synthesis in parasites and certain microorganisms.
Pyrimethamine inhibits dihydrofolate reductase, blocking the synthesis of tetrahydrofolate and thereby preventing DNA synthesis in parasites and certain microorganisms. Used for Malaria (treatment and prophylaxis), Toxoplasmosis, Pneumocystis jirovecii pneumonia (PCP) prophylaxis and treatment.
At a glance
| Generic name | Pyrimethamine (PYR) |
|---|---|
| Sponsor | Erasmus Medical Center |
| Drug class | Antifolate antimalarial and antiparasitic agent |
| Target | Dihydrofolate reductase (DHFR) |
| Modality | Small molecule |
| Therapeutic area | Infectious Disease |
| Phase | FDA-approved |
Mechanism of action
Pyrimethamine is a competitive inhibitor of dihydrofolate reductase (DHFR), an enzyme essential for converting dihydrofolate to tetrahydrofolate in the one-carbon transfer pathway. By blocking this enzyme, it depletes tetrahydrofolate pools, which are critical cofactors for nucleotide synthesis. This mechanism is particularly effective against parasites and certain bacteria that cannot salvage preformed nucleotides from their host, making them dependent on de novo synthesis.
Approved indications
- Malaria (treatment and prophylaxis)
- Toxoplasmosis
- Pneumocystis jirovecii pneumonia (PCP) prophylaxis and treatment
Common side effects
- Megaloblastic anemia
- Thrombocytopenia
- Leukopenia
- Rash
- Gastrointestinal disturbances
- Folate deficiency
Key clinical trials
- Combining Latency Reversing Agents to Address the HIV Reservoir (PHASE1, PHASE2)
- Sanaria PfSPZ Challenge With Pyrimethamine Chemoprophylaxis (PfSPZ-CVac Approach): Phase 1 Trial to Determine Safety and Protective Efficacy of Sanaria PfSPZ Challenge With Concurrent Pyrimethamine Treatment That Inhibits Development of Asexual B... (PHASE1)
- ACT MALI: Treatment of Malaria Based on Combination Therapies (PHASE4)
Primary sources
Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.
| Source | Used for |
|---|---|
| ClinicalTrials.gov | Trial enrolment, design, endpoints, results |
Competitive intelligence
For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:
- Pyrimethamine (PYR) CI brief — competitive landscape report
- Pyrimethamine (PYR) updates RSS · CI watch RSS
- Erasmus Medical Center portfolio CI