Name: Trimethoprim-Sulfamethoxazole (Bactrim, Septra)
Class: Antimicrobial
Mechanism: Acts on two sequential steps in synth of folic acid. PABA competitive inhib, dihydrofolate reductase inhib. Bacteriostatic.
Absorption: Oral, IV
Distrib.:
Metabolism.:
Excretion, t½:
Toxicity/S.E.s: Megaloblastic anemia, leukopenia, granulocytopenia (prevented by admin. of folic acid)
Utility: Uncomp. UTIs, otitis media, acute exacerbations of chronic bronchitis, various pneumonias. DOC for Travelers’ diarrhea (esp. in kids), P. carinii pneumonia, Shigella enteritis, systemic Salmonella infects, prostatitis.
Special Features: Trimethoprim = highly selective inhib. of bacterial dihydrofolate reductase. For diarrhea, treat until symptoms resolve, or no longer than 3 days.