Prescribing prophylactic co-trimoxazole

Co-trimoxazole is a combination product containing sulfamethoxazole and trimethoprim, which are two inhibitors of bacterial folic acid synthesis (National Center for Biotechnology Information). The two components act synergistically, providing a bacteriostatic effect, which is used to treat or prevent a range of Gram positive or negative infections. One indication for cotrimoxazole is for the treatment and prevention of pneumonia caused by Pneumocystis jirovecii.

The BNF (Joint Formulary Committee, 2019) recommended doses for treating pneumonia from this cause are listed in Box 1.

Box 1.Treatment for Pneumocystis jirovecii (Pneumocystis carinii) infections (undertaken where facilities for appropiate montioring avaliable–consult microbiologist and product literature)By mouth, or by intravenous infusionFor child120 mg/kg daily in 2–4 divided doses for 14–21 days, oral route preferred for childrenFor adult120 mg/kg daily in 2–4 divided doses for 14–21 days

What would be the ideal four times daily intravenous treatment dose for a 48 kg adult?