Sulfonamides: Sulfamethoxazole, Sulfisoxazole, and Sulfadiazine
–
Gram-positive
– Gram-negative bacteria
–
Chlamydiae
–
Nocardia
– Commonly used to treat infections of the urinary and lower respiratory tracts:
MRSA pneumonia, Otitis media and some cases of gonorrhea
– Trimethoprim is often combined with sulfamethoxazole for bactericidal effects
TMP/SMX, aka, Bactrim.
– Sulfonamides competitively bind dihydropteroate synthase (in place of para-aminobenzoic acid ((PABA))
Inhibit early steps in folic acid synthesis
– Trimethoprim inhibits dihydrofolate reductase
– Enzyme modification
– Reduction of drug uptake
– Increased drug efflux
– Increased PABA synthesis
- Adverse effects of Sulfonamides
– Hypersensitivity, with potential for Stevens-Johnson syndrome or toxic epidermal necrolysis
– Drug-induced hemolytic anemia, which is more likely in individuals with G6PD deficiencies
– Nephrotoxicity
– Aseptic meningitis, specifically associated with TMP/SMX
