Comparison between sulbenicillin and piperacillin levels in serum and in bronchial secretions--a pharmacokinetic study.

: In order to assess pharmacokinetic differences between sulbenicillin (S) and piperacillin (P), two penicillin derivatives, 24 in-patients, 12 males and 12 females mean age 59.4 years, suffering from recurrent bronchial infections were enrolled. Patients were randomly allocated to S (12 patients) and to P (12 patients) and were given 2 g i.m. every 12 h of the awarded antibiotic, for a 7-day period. At the first and 7th day blood samples (0.25, 0.5, 1, 2, 4, 6, 8 and 12 h after dosing) as well as sputum samples (1, 2, 4, 8, 12 h after dosing) and urine samples (3, 6, 9 and 12 h after dosing) were collected, and the levels of S or P were determined by bacillus subtilis test. The pharmacokinetic analysis was performed by a standard program. On day 1 and 7 the mean peak serum concentration occurred at the first hour for S (39.9 +/- 5.2; 40.9 +/- 5.1 mcg/ml, respectively) and for P (32.2 +/- 5.4; 33.1 +/- 5.4 mcg/ml, respectively). Serum AUC0-12 and AUC0-00 (mg/l.h) levels of S were significantly higher (p less than 0.01 or less) than those of P on day 1 and 7. Similarly MRT (8 h) and Cmax (mg/l) where higher but only on day 7. Sputum AUC0-12 (mg/l.h) level of S was significantly higher (p less than 0.05) than that of P on day 1 and 7. In conclusion serum and sputum S appear to have a different pharmacokinetic profile in respect to P. However, when compared to the AUC, both drugs reach antibacterial levels.