[Pharmacokinetics of cefotetan and an aminoglycoside preparation in combined administration. 1. Individual quantification of cefotetan and sisomicin by bioassay and their absorption, distribution, and excretion in rats when given together].
The beta-lactam and aminoglycoside groups of antibiotics are often used in combination. This paper reports a bioassay method for each of cefotetan and sisomicin concentration in body fluids, and pharmacokinetics of both drugs following intravenous administration of cefotetan and intramuscular administration of sisomicin alone and in combination to rats. As to cefotetan determination, a previously reported bioassay method was modified by increasing the NaCl concentration in the sensitivity test agar from 0 to 6%, using Bacillus subtilis ATCC 6633 as the test organism. To assay for sisomicin in the presence of cefotetan, Pseudomonas aeruginosa ATCC 8689, resistant to the beta-lactam antibiotic, was used. Cefotetan (20 mg/kg intravenous) and sisomicin (10 mg/kg intramuscular) were administered concomitantly to rats. The mean plasma concentrations of cefotetan and sisomicin were 16.3 microgram/ml and 16.1 microgram/ml, at 30 minutes after administration respectively. The concentrations were declined to 2.20 microgram/ml for cefotetan and 2.53 microgram/ml for sisomicin at 90 minutes after dosing administration. The calculated plasma half-lives (T 1/2 beta) were 21.3 minutes for cefotetan and 22.2 minutes for sisomicin. The plasma and tissue concentrations of cefotetan administered in combination with sisomicin were nearly the same as those of cefotetan alone. Urinary excretion of cefotetan and sisomicin in the concomitant administration was carried out in rats. Recoveries in urine were 45.9% of the dose for cefotetan and 85.6% of the dose for sisomicin for a period of 24 hours. When each drug was administered alone to rats, cefotetan and sisomicin were recovered 49.8% and 81.6%, respectively, of the dose in the 24-hour urine.
D000042:Absorption; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000378:metabolism; D001681:Biological Assay / Q000379:methods; D015313:Cefotetan; D002511:Cephalosporins / Q000378:metabolism*; D002513:Cephamycins / Q000008:administration & dosage / Q000378:metabolism*; D005839:Gentamicins / Q000008:administration & dosage* / Q000378:metabolism*; D007273:Injections, Intramuscular; D007275:Injections, Intravenous; D007668:Kidney / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012853:Sisomicin / Q000008:administration & dosage* / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D002513:Cephamycins; D005839:Gentamicins; D015313:Cefotetan; D012853:Sisomicin