Plasma and urine pharmacokinetics of two formulations of dexamethasone in greyhound dogs

Abstract

Dexamethasone, formulated as sodium phosphate and as phenylpropionate combined with sodium phosphate, was administered subcutaneously to six greyhounds. Plasma and urine were collected for up to 240 h and analysed with a limit of quantification (LOQ) of at least 100 pg/ml for dexamethasone. Dexamethasone, formulated as sodium phosphate, terminal half‐life was 10.4 h in plasma and approximately 16 h in urine, and at 96 h, plasma hydrocortisone concentrations returned to background with dexamethasone levels around the LOQ. Dexamethasone, formulated as phenylpropionate combined with sodium phosphate, terminal half‐life, was 25.6 h in plasma and approximately 26 h in urine, and at 96 h, plasma hydrocortisone concentrations returned to background with dexamethasone levels in three of the six greyhounds around the LOQ. Critical assessment of the pharmacokinetic and pharmacodynamic data indicated how it might be utilized for medication control in racing greyhounds.

Pharmacology of drugs used in autoimmune dermatopathies in cats and dogs: A narrative review

“…15 Using a very sensitive assay, dexamethasone was detected in the plasma of Greyhound dogs for ≤96 h post-administration of approximately 0.05 mg/kg dexamethasone sodium. 16 Despite the long detection time, dexamethasone suppression of endogenous cortisol production was not significant after 24 h. The PK of oral dexamethasone in dogs is not published. There are studies available that report the PK of oral dexamethasone in cats following a single dose of injectable dexamethasone sodium phosphate administered at 0.05 or 0.2 mg/kg.…”

“…Dogs administered 1 mg/kg of dexamethasone in alcohol (intravenously) or as isonicotinate (intramuscularly) had drug detectable for 10 h post‐administration 15 . Using a very sensitive assay, dexamethasone was detected in the plasma of Greyhound dogs for ≤96 h post‐administration of approximately 0.05 mg/kg dexamethasone sodium 16 . Despite the long detection time, dexamethasone suppression of endogenous cortisol production was not significant after 24 h. The PK of oral dexamethasone in dogs is not published.…”