Pharmacokinetics and antibacterial activity of two gentamicin products given intramuscularly

The pharmacokinetics and antibacterial activity of two injectable gentamicin products given i.m. were compared. Ten healthy men randomly received either Schering or Invenex gentamicin 1 mg/kg (as the sulfate salt) by intramuscular injection into the deltoid muscle. Four to six weeks later, subjects received the alternate preparation at the same dose in the opposite arm. Blood samples for gentamicin concentrations were obtained before drug administration and at various times for up to four hours after drug administration; urine from each subject was also collected before and after drug administration. Values for area under the curve, elimination rate constant, peak serum gentamicin concentration and time to peak concentration, clearance, half-life, and percentage of drug excreted in the urine over four hours were compared for each preparation in each subject. The serum inhibitory and bactericidal activities of each gentamicin preparation against Escherichia coli and Klebsiella pneumoniae were also evaluated. None of the pharmacokinetic values for the two preparations was significantly different. The inhibitory and bactericidal activities resulting from each product were also comparable and adequate. No clinically important differences in pharmacokinetic behavior or inhibitory or bactericidal activity were found between gentamicin products of Schering and Invenex.