Sulfamethoxazole
in BACTRIM
“Sulfa mask”
Needs a back trim → paired with TMP in Bactrim
What it isSulfonamide blocking dihydropteroate synthase, paired with trimethoprim; urinary infection, MRSA skin infection and PJP.
Why this oneThe sequential blockade with trimethoprim is synergistic, and it is the only oral first-line agent for Pneumocystis.
What limits itHyperkalemia, severe cutaneous reactions, and it raises warfarin effect through CYP2C9. Avoid in late pregnancy and G6PD deficiency.
FDA-approved for
- bacterial infections (~1961)
NO BOXED WARNINGS
Principal riskHyperkalemia and severe cutaneous reactions
Classes and tags
Clinical profile
Defining liabilitySulfonamide hypersensitivity and crystalluria
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