The dosage of co-trimoxazole in childhood.

Co-trimoxazole, a mixture of one part trimethoprim (TMP) and five parts of sulphamethoxazole (SMX) in fixed ratio was given to 48 children aged between one and 48 months twice daily for up to seven days. Twenty were relatively healthy and 28 were very ill. Dosage was based on age. Plasma concentrations of both drugs were measured just before a dose was due and some three hours later. They were in the efective but not toxic range and serve to justify the simple regimen which generated them.