Influence of short-term water deprivation on antipyrine disposition in calves

Effects of water deprivation on drug pharmacokinetics: correlation between drug metabolism and hepatic CYP isozymes

Male Sprague-Dawley rats deprived of water for 72 h (a rat model of dehydration) showed no change in protein expression of the hepatic microsomal cytochrome P450 (CYP) 1A2, 2B1/2, 2C11, or 3A1/2, but an increase in protein expression (3-fold) and mRNA level (2.6-fold) of CYP2E1. Glucose feeding instead of food normalized CYP2E1 protein expression during dehydration. Here, we review how dehydration can change the pharmacokinetics of drugs reported in the literature via changing CYP isozyme levels. We also discuss how dehydration changes the pharmacokinetics of drugs that are metabolized via renal DHP-I, or are mainly excreted in the urine and bile, and form conjugates.

The effect of food or water deprivation on paracetamol pharmacokinetics in calves

This study investigated the effect of food or water deprivation on the pharmacokinetics of paracetamol in 30 Holstein-Friesian preruminant calves (10 controls, 10 food withheld and 10 water-deprived) aged 24-25 days. Control calves were given paracetamol at 24-25 days and again at 28-29 days of age. In the food withheld and water-deprived calves paracetamol studies were performed before and after 4 days of food or water deprivation. In the control group there were no significant differences in pharmacokinetic parameters for paracetamol in 24-25 and 28-29-day-old calves. Witholding food for 4 days was associated with an increase in the mean residence time (MRT) of paracetamol (P < 0.01). When food was withheld total body clearance (ClB) of paracetamol was significantly decreased (P < 0.05). The volume of distribution (Vss) was not significantly altered. Similarly, water deprivation was associated with a significant increase in MRT and significant decrease in ClB of paracetamol (P < 0.01). The Vss was not significantly altered. Food or water deprivation also influenced the formation of major metabolites (glucuronide and sulphate) of paracetamol. It is concluded that food or water deprivation may impair the elimination drugs that undergo metabolism by UDP-glucuronyltransferase and sulphotransferase in cattle.

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.

Effect of experimental fasciolosis on antipyrine metabolism and clearance in water buffaloes

The effect of chronic Fasciola hepatica infection on the metabolism of antipyrine, a marker of microsomal oxidative metabolism, was investigated in male water buffaloes dosed daily with 60 F. hepatica metacercariae over 20 days. The plasma elimination half-life of antipyrine was significantly elevated by 23% at 11 weeks postinfection (p.i.) but did not significantly differ from the control period at 20 weeks p.i. The systemic clearance of antipyrine decreased by 48% at 11 weeks p.i. and then returned to normal. The renal clearance for each of the main antipyrine metabolites decreased at 11 weeks p.i. (hydroxymethylantipyrine (HMA), -42%; norantipyrine (NORA), -58%; and 4-hydroxyantipyrine (OHA), -70%) and did not significantly differ from the control period at 20 weeks p.i. These findings indicate that experimental subclinical fasciolosis leads to altered antipyrine kinetics and to an inhibition of the different antipyrine metabolic pathways in water buffaloes.