[Pharmacokinetics of ceftizoxime with and without probenecid]

Serum concentrations and urinary recovery of ceftizoxime were investigated in 18 healthy volunteers. The substance was given as a bolus (2 min) i.v. injection. In volunteers the injection was preceded by orally administered probenecid, 500 mg, 7 and 1 h before (Group II); the remaining 12 volunteers received medication. 5 min after the injection, the serum concentration in Group I was 107 +/- 22 micrograms/ml and in II 93 +/- 18 micrograms/ml in the mean; 30 min after the injection in I 45 +/- 8 micrograms/ml and 44 +/- 10 micrograms/ml in II. The further of the serum concentration was slower in II than in I: serum concentration 6 h after the injection was 2.6 +/- 0.9 micrograms/ml in I and 4.4 +/- 2 micrograms/ml in II. During the first 8-h period 81% of the administered cephalosporin was recovered in the urine of I and 58% in the urine of II. t/2 beta was calculated for I with 1.76 h and 2.13 h for II. The distribution volume was equal, so that the differences in serum concentrations could be explained by the reduced renal clearance: from 2.1 to 1.4 ml/s. Because the comparison was done with two independent groups and furthermore only 6 volunteers participated in the probenecid group, only the difference in the urine in the first 2 h was statistically significant.