Pharmacokinetics of gentamicin administered intravenously to water-deprived goats

The pharmacokinetics of gentamicin sulphate administered intravenously (3 mg/kg body weight) were studied in dehydrated Nubian goats, which had lost an average of 7.2, 10.4 or 12.8% of their body weights owing to water deprivation for 2, 3 or 4 days, respectively. The pharmacokinetic parameters were described by a two-compartment open model. A significant decrease was observed in total body clearance (p < 0.05) following strict water deprivation with an average 7.2% loss in body weight. No statistically significant changes were found in the distribution parameters of the drug at this dehydration level. In dehydrated goats which had lost about 10.4 or 12.8% body weight, mean plasma concentrations were significantly higher (p < 0.05). Clearance was decreased (p < 0.001) corresponding to a substantial increase in the half-life of elimination. Reduction was observed in the volume of distribution at steady state (Vdss) compared with normally hydrated goats (p < 0.05). The alterations in the pharmacokinetics of gentamicin observed in the present study justify the need for an adjustment of the gentamicin therapeutic dosage regimen in dehydrated animals. (C) 1999 Elsevier Science B.V. All rights reserved.