Trimethoprims affinity for bacterial dihydrofolate reductase is several thousand times greater than its affinity for human dihydrofolate reductase. Sulfamethoxazole inhibits dihydropteroate synthase, an enzyme involved further upstream in the same pathway. Trimethoprim and sulfamethoxazole are commonly used in combination due to possible synergistic effects, and reduced development of resistance. This benefit has been questioned. History
Trimethoprim was first used in 1962. In 1972, it was used as a prophylactic treatment for urinary tract infections in Finland.Its name is derived from trimethyloxy-pyrimidine. See also
Tetroxoprim
Iclaprim

References
External links
"Trimethoprim". Drug Information Portal. U.S. National Library of Medicine.
References
External links

Medline Plus article on Nasal Discharge