Pharmacokinetics of dexamethasone after intravenous and intramuscular administration in pigs

The pharmacokinetics of dexamethasone (DEX) were investigated after an intravenous (IV) or intramuscular (IM) bolus injection of 0.3 mg/kg bodyweight DEX sodium phosphate in pigs. The plasma concentrations of DEX were determined using a validated high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method and the pharmacokinetics were determined by one-compartmental analysis. The mean area under the plasma concentration-time curve and the mean elimination half-life were 133.07 +/- 39.59 ng.h/mL and 0.77 h, and 173.24 +/- 53.59 ng h/mL and 1.06 h following IV and IM administration, respectively. The volume of distribution and clearance recorded after IV administration were 2.78 +/- 0.88 L/kg and 2.39 +/- 0.57 L/h kg, respectively. An IM bolus injection of DEX sodium phosphate in pigs resulted in a fast and complete absorption, with a mean maximal plasma concentration of 80.94 +/- 21.29 ng/mL at 0.35 +/- 0.21 h and a high absolute bioavailability of 131.06 +/- 26.05%. (C) 2013 Elsevier Ltd. All rights reserved.