Systemic dexamethasone concentration in horses after continued topical treatment with an ophthalmic preparation of dexamethasone
Spiess, B.M.; Nyikos, S.; Stummer, E.; Sahin, A.; Naegeli, H.
American Journal of Veterinary Research 60(5): 571-576
1999
ISSN/ISBN: 0002-9645 PMID: 10328426 Document Number: 507521
Dexamethasone ophthalmic ointment (0.1%) was administered to the left eye of 4 horse every 5 to 9 h for 8 consecutive days, yielding an estimated cumulative dexamethasone dose of 6.4 micro g/kg body weight. Serum and urine samples were obtained before the first dexamethasone treatment, on days 4 and 8 of treatment, and 24, 48 and 96 h after cessation of treatment. Serum and urine samples were analysed using a competitive enzyme immunoassay. During the period of continued topical treatment, serum dexamethasone concentrations increased to between 0.10 and 0.49 ng/ml, then decreased below the limit of detection (0.06 ng/ml) within 24 h after cessation of treatment. Dexamethasone was also detected in urine samples at concentrations of up to 0.98 ng/ml. It is suggested that owners and trainers of performance horses should reconsider entering horses in competitions during periods of treatment with ophthalmic dexamethasone preparations.