EFFECT OF DEHYDRATION ON THE PHARMACOKINETICS OF OXYTETRACYCLINE HYDROCHLORIDE ADMINISTERED INTRAVENOUSLY IN GOATS (CAPRA-HIRCUS)

1. The effects of various levels of dehydration induced by water depri vation were stud led in six Nubian goats on the pharmacokinetics of ox ytetracycline after intravenous administration (5 mg/kg). 2. In goats that had lost an average of 7.6% body weight after 2 days of water dep rivation, the elimination rate constant of the drug was significantly decreased (P < 0.01) and the total body clearance was significantly sl ower (P < 0.001). No statistically significant changes were observed i n the pharmacokinetic parameters describing the distribution of the dr ug at this dehydration level. 3. Water deprivation for 3 or 4 days res ulted in a level of dehydration at which the goats lost an average of 10.3% or 12.7% of their body weight, respectively; significant changes were observed in the pharmacokinetic distribution and elimination par ameters of oxytetracycline. The volume of distribution at steady state was significantly decreased (P < 0.01). Significantly slower total bo dy clearance (P < 0.001) and subsequent prolongation of the eliminatio n half-life were found at these dehydration levels. 4. The alterations caused by dehydration on the disposition kinetics of the drug should be considered for better definition of dosage regimens for sick, dehyd rated animals. (C) 1998 Elsevier Science Inc.