antibioticsbooks

Folate Antagonists
17
Agents: trimethoprim/sulfamethoxazole
(TMP/SMX), dapsone, pyrimethamine,
sulfadiazine, sulfadoxine
The combination drug TMP/SMX is the most
widely used folate antagonist, active against both
bacterial and parasitic/fungal infections. TMP/
SMX was once considered a broad-spectrum antibacterial
drug that has since fallen victim to the
relentless march of antibiotic resistance; however,
it is still a drug of choice for a number of indications.
Resistance varies considerably by geographic
region, so consider your local antibiogram before
using TMP/SMX as empiric therapy. The other
agents are used against parasitic/fungal infections.
The information below refers to TMP/SMX except
where noted.
Mechanism of Action
These drugs inhibit steps in the folate biosynthesis
pathway, depleting the pool of nucleosides and ultimately
leading to inhibition of DNA synthesis in
susceptible organisms.