The relative bioavailability of co-trimoxazole suspensions

The relative bioavailability of a co-trimoxazole suspension manufactured by VEB Berlin-Chemie (B); Belocid-Suspension was compared with a widespread used suspension (V) in healthy male students (22-29 ys. aged). A single oral dose of 160 mg trimethoprim (TPM) and 800 mg sulphamethoxazole (SMZ) produced similar blood levels with either preparation. The TMP peak levels were 1.44 +/- 0.18 (B) and 1.40 +/- 0.26 mg/l (V), respectively after 1.5 and 1.0 h on an average. The AUC amounted to 18.94 +/- 2.25 (B) and 17.19 +/- 3.62 mg . h/l (V), respectively. About one half (52.5%) of the given TMP dose was excreted unchanged by kidney within 48 h after administration of the respective suspension. The SMZ peak levels run to 37.2 +/- 10.3 (B) and 38.6 +/- 5.4 mg/l (V) after 3.6 +/- 3.5 and 1.3 +/- 0.8 h. The AUC were identical: 682.3 +/- 126.2 (B) vs. 686.9 +/- 165.8 mg . h/l (V). After both preparations 67% of the given SMZ dose could be detected in urine within 48 h. In two out of the eight volunteers the absorption of B was delayed, but it passed off to the same extent. In all other cases absorption of the suspension was accelerated in comparison with tablet administration studies reported. Peak blood levels of TMP and SMZ after ingestion of the suspensions reach the lower range of values resulting from tablet intake. Both suspensions are regarded interchangeable with respect to bioavailability, which is also comparable to co-trimoxazole tablets.