Penetration of topically administered corticosteroids in normal equine ocular fluids

Study Design: Prospective randomized experimental pharmacokinetic study.

Methods

Twenty-one Shetland ponies without ophthalmic disease were treated bilaterally topically every 2 hours during 24 hours to obtain steady-state drug concentrations. One eye was treated with 0.15 mg dexamethasone disodium phosphate (0.1%) and the other eye was simultaneously treated with 1.5 mg prednisolone acetate (1%). Serum samples were taken prior to induction of general anaesthesia.

Aqueous and vitreous humour samples were taken during euthanasia at time points after administration of the last dose (t=5min, t=15min, t=30min, t=60min, t=90 min, t=120min, t=180min). Each pony was randomly assigned to one time point and 3 ponies were sampled per time point. Dexamethasone and prednisolone concentrations were measured by liquid chromatography-mass spectrometry.