The effect of short-term starvation or water deprivation on caffeine pharmacokinetics in calves.

The aim of this study was to determine the effect of short-term starvation or water deprivation on the pharmacokinetics of caffeine in calves. The experiment was carried out on 30 Holstein-Friesian calves (10 calves in a control group, 10 calves in a 'starved' group and 10 calves in a 'water-deprived' group) aged 24-25 days. Control group calves were given caffeine at 24-25 and 28-29 days of age. In the experimental groups caffeine studies were performed before and after 4 days of starvation or water deprivation. In the control group no significant differences between the pharmacokinetic parameters of caffeine in 24-25 and 28-29 day-old calves were observed. Starvation for 4 days was associated with an increase in the mean residence time (MRT) of caffeine in each subject. The increase was statistically significant (P < 0.01). After starvation the total plasma clearance of caffeine decreased (about 20 per cent). The decrease was statistically significant (P < 0.05). The volume of caffeine distribution (V(ss)) was slightly but not significantly increased. Similarly, water deprivation was associated with significant increase in the mean residence time of caffeine in each subject. The total plasma clearance of caffeine decreased (about 30 per cent). This decrease was statistically significant (P < 0.01). The volume of caffeine distribution was slightly but not significantly decreased. Results obtained in this study indicate that short-term (for 4 days) starvation or water deprivation leads to a general inhibition of hepatic P450 enzymatic system and may impair the elimination of drugs that undergo metabolism by these enzymes.