Effects of water deprivation for 72 hours on the pharmacokinetics of a new carbapenem, DA-1131, in rats

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.

Effects of water deprivation on the pharmacokinetics of theophylline and one of its metabolites, 1,3-dimethyluric acid, after intravenous and oral administration of aminophylline to rats

It has been reported that the expressions of hepatic microsomal cytochrome P450 (CYP) 1A1/2, 2B1/2 and 3A1/2 were not changed in rats with water deprivation for 72 h (rat model of dehydration) compared with the controls. It has been also reported that 1,3-dimethyluric acid (1,3-DMU) was formed from theophylline via CYP1A1/2 in rats. Hence, it could be expected that the formation of 1,3-DMU could be comparable between the two groups of rats. As expected, after both intravenous and oral administration of theophylline at a dose of 5 mg/kg to the rat model of dehydration, the AUC of 1,3-DMU was comparable to the controls. After both intravenous and oral administration of theophylline to the rat model of dehydration, the Cl(r) of both theophylline and 1,3-DMU was significantly slower than the controls. This could be due to significantly smaller urinary excretions of both theophylline and 1,3-DMU since the AUC of both theophylline and 1,3-DMU were comparable between the two groups of rats. The smaller urinary excretion of both theophylline and 1,3-DMU could be due to urine flow rate-dependent timed-interval renal clearance of both theophylline and 1,3-DMU in rats.

Effects of glucose supplementation on the pharmacokinetics of intravenous chlorzoxazone in rats with water deprivation for 72 h

It was reported that in rats with water deprivation for 72 h with food (dehydration rat model), the expression of CYP2E1 was 3-fold induced with an increase in mRNA level and glucose supplementation instead of food during 72-h water deprivation (dehydration rat model with glucose supplementation) inhibited the CYP2E1 induction in dehydration rat model. It was also reported that chlorzoxazone (CZX) is metabolized to 6-hydroxychlorzoxazone (OH-CZX) mainly via CYP2E1 in rats. Hence, the effects of glucose supplementation on the pharmacokinetics of CZX and OH-CZX were investigated after intravenous administration of CZX at a dose of 25 mg/kg to control male Sprague-Dawley rats and dehydration rat model and dehydration rat model with glucose supplementation. Based on the above mentioned results of CYP2E1, it could be expected that increased formation of OH-CZX in dehydration rat model could decrease in dehydration rat model with glucose supplementation. This was proven by the following results. In dehydration rat model with glucose supplementation, the AUC of OH-CZX was significantly smaller (1900 versus 1050 microg min/ml), AUC(OH-CZX)/AUC(CZX) ratio was considerably smaller (105 versus 34.3%), C(max) was significantly lower (20.6 versus 8.08 microg/ml), total amount excreted in 24-h urine as unchanged OH-CZX was significantly smaller (62.3 versus 42.7% of intravenous dose of CZX), and in vitro V(max) (2.18 versus 1.20 nmol/min/mg protein) and CL(int) (0.0285 versus 0.0171 ml/min/mg protein) were significantly slower than those in dehydration rat model.

Effects of water deprivation for 72 hours on the pharmacokinetics of DA-7867, a new oxazolidinone, in rats

The pharmacokinetic parameters of DA-7867 were compared after intravenous and oral administration at a dose of 10 mg/kg in control rats and in rats with water deprivation for 72 h (rat model of dehydration). After intravenous administration in the rat model of dehydration, the Cl(nr) (0.654 versus 0.992 ml/min/kg) and Cl(r) (0.0273 versus 0.0784 ml/min/kg) values were significantly slower than in the controls. The slower Cl(nr) could be due mainly to a significantly smaller total amount of unchanged DA-7867 recovered from the gastrointestinal tract at 24 h (GI(24 h): 5.16% versus 9.21% of intravenous dose) due to impaired liver function in the rat model of dehydration. The slower Cl(r) could be due mainly to a significantly smaller 24 h urinary excretion of unchanged drug (Ae(0-24 h): 4.41% versus 7.75% of intravenous dose) due to urine flow rate-dependent Cl(r) of DA-7867 in the rat model of dehydration. Hence, the Cl was significantly slower in the rat model of dehydration (0.677 versus 1.07 ml/min/kg). After intravenous administration in the rat model of dehydration, the V(ss) of DA-7867 was significantly smaller than in the controls (396 versus 506 ml/kg) due mainly to significantly smaller free (unbound to plasma proteins) fractions of DA-7867 in plasma (6.90% versus 29.2%) in the rat model of dehydration. After oral administration in the rat model of dehydration, the AUC was significantly greater than that in controls (10800 versus 7060 microg min/ml) due mainly to a significantly smaller Ae(0-24 h) than in controls (3.50% and 6.17% of oral dose).

Pharmacokinetics of oltipraz after intravenous and oral administration in rats with dehydration for 72 hours

Pharmacokinetic parameters of oltipraz were compared after intravenous and oral administration at a dose of 30 mg/kg to control rats and rats with water deprivation for 72 h (rats with dehydration). The plasma protein binding of oltipraz was measured in both groups of rats using an equilibrium dialysis technique. The concentrations of oltipraz were measured by the reported HPLC analysis. After intravenous administration, the total area under the plasma concentration-time curve from time zero to time infinity (AUC), terminal half-life, time-averaged total body and nonrenal clearances, and apparent volume of distribution at steady state were not significantly different between the two groups of rats. However, after oral administration to rats with dehydration, the AUC was significantly smaller than that in control rats (180 versus 316 microg min/ml) mainly due to decrease in absorption. In rats with dehydration, plasma protein binding was significantly greater than that in control rats (91.5 +/- 0.309 versus 81.3 +/- 2.79%).