[Diffusion of trimethoprim and sulfamethoxazole into the pleural fluid].

The level of Trimethoprim (TMP) and of Sulfamethoxazole (SMZ) in the fluid of both pleural effusion and plasma was determined in 7 patients on the first day of treatment consisting of two daily doses of 160 mg TMP and 800 mg SMZ. In 4 subjects, the levels were determined again on the third (J3) and fifth day of treatment (J5). Thus with TMP the ratio of pleural/plasma drug levels rose progressively from the first day of treatment to attain by 12 hours a mean value of 0.79 +/- 0.16; subsequently it stayed at about the same level for day 3 (J3) and day 5 (J5). As for SMZ, the ratio of the pleural plasma drug level reached a maximum at 8 hours on the first day of treatment (0.53 +/- 0.12) then rose progressively on day 3 (J3 0.58 +/- 0.06) and on day 5 to 0.71 (+/- 0.08). The levels of TMP in the pleural fluid were below those which are usually described in bronchial secretions. On the other hand those of SMZ are appreciably raised.