Sulfamethazine is a synthetic chemotherapeutic agent from the sulfamide group. Trimethoprim is a synthetic chemotherapeutic agent derived from diaminopyrimidine.
Separately, each component has a bacteriostatic mechanism, but sulfamethazine and trimethoprim, taken in a 4: 1 ratio, enhance the effect of the drug and give it a bactericidal nature of action.
Such synergy is manifested due to the fact that its components affect two sequential processes that are necessary for the synthesis of tetrahydrofolic acid or bacterial folic acid, which plays a major role in the synthesis of bacterial purines. The bacterial wall is impermeable to folates, so the synthesis of purines depends on the intrinsic synthesizing ability of microorganisms.