Penetration of trimethoprim and sulphamethoxazole into the aqueous humour.

Abstract

Trimethoprim (TM) (2,4-diamino-5-(3,4,5-trimethoxybenzyl)-pyrimidine) is an anti- bacterial agent. It blocks the folic acid synthesis of bacteria in the manner of the sulphonamides, but acts at a different stage in the synthesis. TM and sulphonamides have a synerg- istic effect (Bushby and Hitchings, i968), and thus a combination ofTM and sulphonamide has a broad-spectrum bactericidal action (B6hni, I969). The sulphonamide used in combined preparations has been sulphamethoxazole (SMZ) which in man has practically the same rate of secretion and elimination as TM, the half-life of both being approximately io hrs (Rieder, I963; Schwartz and Ziegler, I969).