PHARMACOKINETICS OF AMPICILLIN-TRIHYDRATE FOLLOWING INTRAVENOUS ADMINISTRATION TO WATER DEPRIVED NUBIAN GOATS

The present study reports the effect of water deprivation in the Nubia n goat on the pharmacokinetics of ampicillin trihydrate following intr avenous administration at a dose rate of 10 mg kg(-1). Water deprivati on for two days, which resulted in about 7.5 per cent loss in bodyweig ht, produced no significant effects on the pharmacokinetic parameters of the drug. In dehydrated goats that had lost an average of 9.8 per c ent of their initial bodyweights, within three days of water deprivati on, ampicillin showed significantly slower clearance values (P<0.001), without affecting significantly the pharmacokinetic parameters descri bing the distribution of the drug. After four days of water deprivatio n a dehydration level at which goats lost an average of 12.6 per cent bodyweight was reached, which resulted in significant alterations in t he distribution and elimination pharmacokinetic parameters of ampicill in. The volume of the central compartment (Vc) and the volume of distr ibution at steady stare (Vdss) were significantly decreased (P<0.01) l eading to significant elevation in plasma concentrations of the drug ( P<0.01) compared with the normally hydrated animals. In water deprived goats, significantly slower clearance of the drug (P<0.001) and reduc ed elimination rate constant (P<0.01) with the subsequent increases in the half-life time were also observed. Dosage intervals between the u sual doses of ampicillin can be increased in dehydrated goats and conc entrations which were high enough to kill susceptible microorganisms c ould still be achieved.