LACK OF EFFECT OF VANCOMYCIN AND GENTAMICIN ON AUDITORY FUNCTION IN GUINEA-PIGS

The dispositions of vancomycin (VCM) and gentamicin (GM) in plasma and perilymph after single and multiple administrations and the effect's of multiple administrations of VCM or GM alone and the combination of both drugs on auditory function were studied in male guinea pigs. The pharmacokinetic parameters of VCM and GM obtained from plasma drug con centration-time data after single and multiple (22 days) intramuscular administrations of VCM (200 mg/kg of body weight) alone and GM (50 mg /kg) alone were not significantly different from those after combined administration of VCM (200 mg/kg) and GM (50 mg/kg). There was no chan ge in the penetration ratio of VCM and GM into perilymph between admin istration of VCM or GM alone and the combination of both drugs. Furthe rmore, the hearing threshold of guinea pigs was not affected by VCM or GM alone or the combination of both drugs within the range of therape utic VCM and GM levels in plasma in humans.