Clinical oral doses of dexamethasone decreases intrinsic clearance of quinidine, a cytochrome P450 3A substrate in dogs.

We investigated the effect of dexamethasone (DEX) at clinical doses on the pharmacokinetics of quinidine (QN) in dogs. Dogs (5 healthy 1-year-old male beagles) were orally administered DEX once daily for 5 days at 2.5 or 7.

Effect of oral administration of clinically relevant doses of dexamethasone on regulation of cytochrome P450 subfamilies in hepatic microsomes from dogs and rats.

Objective: To evaluate the effect of oral administration of dexamethasone (DEX) at clinically relevant doses on metabolic activities of cytochrome P450 (CYP) isoenzymes in dogs and rats.

Animals: 15 healthy 1-year-old male Beagles and 20 healthy 10-week-old male Wistar rats.

Procedure: Hepatic microsomes were harvested from dogs treated orally with DEX at 2.

In vitro characterization of the inhibitory effects of ketoconazole on metabolic activities of cytochrome P-450 in canine hepatic microsomes.

Objective: To evaluate the inhibitory potency of ketoconazole (KTZ) on the metabolic activities of isozymes of cytochrome P-450 (CYP) in dogs.

Animals: 4 healthy 1-year-old male Beagles.

Procedure: Hepatic microsomes were harvested from 4 dogs after euthanasia.

Effect of oral ketoconazole on first-pass effect of nifedipine after oral administration in dogs.

The long-term oral ketoconazole (KTZ) treatment extensively inhibits hepatic CYP3A activity. We investigated the effect of the KTZ treatment on hepatic and intestinal extraction of nifedipine (NIF) using beagle dogs. Four dogs were given orally KTZ for 20 days (200 mg, bid).

Effect of multiple dosing of ketoconazole on pharmacokinetics of midazolam, a cytochrome P-450 3A substrate in beagle dogs.

To evaluate effects of multiple dosing of ketoconazole (KTZ) on hepatic CYP3A, the pharmacokinetics of intravenous midazolam (MDZ, 0.5 mg/kg) before and during multiple dosing of KTZ were investigated in beagle dogs. KTZ tablets were given orally to dogs (n = 4) for 30 days (200 mg b.