Bioequivalence of ceftriaxone intramuscular injections

Abstract

Three brands of 1 g. ceftriaxone intramuscular injections were evaluated. The in vitro studies showed that all brands met the requirements of the United States Pharmacopoeia XX111 for weight variations and content of active ingredients, indicating they were pharmaceutically equivalent. Reconstituted products of all brands were stable for about one week when refrigerated at 4 ℃, while at 30℃ they were not. Brand B was the least stable products. The bioequivalence of all three brands of 1 g. ceftriaxone intramuscular injections were conducted in twelve Thai male healthy volunteers using a single dose in a crossover design. Blood samples were determined for ceftriaxone contents by HPLC technique. Individual plasma profile was analyzed by PCNONLIN computer program. Results demonstrated that there were no statistically significant differences (p> 0.05) among the corresponding pharmacokinetic parameters of all brands, ie. the mean peak plasma concentration, the time to attain the peak plasma concentration and the area under the plasma concentration – time curve, referring all brands were bioequivalent in terms of both the rate and extent of drug absorption into systemic circulations. Pharmacokinetics of ceftriaxone following intramuscular injection 1 g. of the drug was best described by mean of one compartment open model with first order input and first order output. The absorption rate constants and the elimination rate constants were in the range of 2.34 to 3.30 hr ⁻¹, and 0.09 to 0.12 hr⁻¹, respectively. The biological half – lifes were found to be between 6.36 to 8.18hr.