Probenecid Ceftazidime

The serum levels of many cephalosporins are raised by probenecid. Possible exceptions include ceforanide, ceftazidime, ceftriaxone and latamoxef. The rise in serum levels may possibly increase the risk of nephrotoxicity with some cephalosporins such as cefal-oridine and cefalotin. 

Ceftazidime Intravenous Probenecid 500 mg every 6 hours for 24 hours before and 1 g immediately before a single intravenous dose of ceftazidime 1 g did not significantly affect ceftazidime clearance. Pharmacokinetics of single 50-mg/l dose of ceftazidime in patients with cystic fibrosis not affected by pre-treatment with probenecid 2 g 19,26... 

Carbon C, Dromer F, BrionN, Cremieux A-C, Contrepois A. Renal disposition of ceftazidime illusttated by interferences by probenecid, furosemide and indomethacin in rabbits. Antimicrob Agents Chemother (1984) 26, 373-7. 

Ceftazidime was dosed intramuscularly and intravenously to human volunteers (Table XII). Peak serum concentrations of 10, 23, and 27 p,g/ ml were obtained after intramuscular doses of 0.25, 0.5, and 0.75 g. The plasma half-life varied from 1.4 hr for the low dose to 1.8 hr for the high dose. Serum concentrations of 8 p,g/ml were still present 1.5 (0.25 g dose), 4.2 (0.5 g dose), and 6.1 hr (0.75 g dose) after intramuscular administration. Urinary recovery of ceftazidime varied from 48 to 88% in 88% in humans. Serum levels of 61 fig/ml were measured immediately after intravenous administration of 0.5 g of ceftazidime to human volunteers. Preliminary experiments indicated that concomitant administration of probenecid had no effect on the rate of excretion of ceftazidime. This indicates that ceftazidime is excreted by glomerular filtration and not by tubular secretion. 

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