title: Pharmacokinetic Study of Cefotaxime (CTX) in Dogs.
abstract: Cefotaxime (CTX) was injected either intravenously or intramuscularly in dogs, and its pharmacokinetics in plasma and urine were determined with the use of HPLC assay. Cephalothin (CET) was administered in a similar manner as a reference agent. While both CTX and CET rapidly disappeared from plasma after intravenous injection, the half-life of CET was approximately 2.5 times shorter than that of CTX. Both drugs were deacetylated, and desacetyl-CTX and desacetyl-CET appeared in plasma. Both drugs were rapidly excreted into urine either in unchanged or deacetylated form, the sum of which accounted for 77 % and 63 % of the CTX and CET dose, respectively. The ratio of the amount of unchanged drug over that of deacetylated drug in the urine was 1:1 for CTX and 1:2 for CET. When CTX and CET were intramuscularly injected, the plasma levels of CTX and CET reached a maximum 30 min and 15 min after injection, respectively, followed by a rapid decline. The pattern of urinary CTX excretion was similar after i.m. and i.v. injections. In contrast, the amount of desacetyl-CET in the urine was larger after i.m. than i.v. injections. CTX metabolites other than desacetyl-CTX (M2 and M3) that were also assayed by HPLC accounted for only 2-4 % of the dose of CTX in the urine, but were below detectable levels in this plasma.
authors.affiliation: Hoechst Japan Limited, Saitama, 350, Japan.
authors.forename: O
authors.initials: O
authors.lastname: Togashi
authors.forename: T
authors.initials: T
authors.lastname: Maeda
authors.forename: M
authors.initials: M
authors.lastname: Omosu
authors.forename: K
authors.initials: K
authors.lastname: Fujimoto
authors.forename: S
authors.initials: S
authors.lastname: Naito