dapsone + trimethoprim

**Dapsone + trimethoprim** is a combination of two oral small molecule antimicrobials sometimes used in the treatment of infections, notably as an alternative regimen for **Pneumocystis pneumonia (PCP)** in patients with AIDS who are intolerant of the standard trimethoprim-sulfamethoxazole regimen. Dapsone acts as a bacteriostatic agent by inhibiting dihydropteroate synthase, thereby blocking folate synthesis in bacteria. Trimethoprim is an antifolate antibacterial that inhibits bacterial dihydrofolate reductase, preventing DNA synthesis and bacterial survival. The combination provides dual inhibition in the folate pathway. Notably, a bidirectional pharmacokinetic interaction exists: dapsone increases trimethoprim concentrations and vice versa, leading to increased toxicity risk, including hematologic effects. Clinical trials show reduced treatment failures in PCP compared with dapsone or trimethoprim alone, but with increased adverse side effects, often necessitating therapy discontinuation[1][3][7].

Brand names

none known specific for this combination

Other names

dapsone + trimethoprim