Application

Trimethoprim is used at a final concentration of ~4μg/mL for antibacterial activty.

Biochem/physiol Actions

Trimethoprim is a synthetic derivative of pyrimidine with antibacterial and antiprotozoal properties. Trimethoprim is an inhibitor of bacterial dihydrofolate reductase (DHFR), interfering with the conversion of dihydrofolate (DHF) to tetrahydrofolate (THF). THF is an essential precursor in the thymidine synthesis pathway, interference with this pathway inhibits bacterial DNA synthesis. Trimethoprim′s affinity for bacterial DHFR is several thousand times greater than its affinity for human DHFR. Trimethoprim is potentiated by Sulfonamides and the Trimethoprim-sulfamethazole combination is the most used form.