Pharmacokinetics of orally administered calcium dobesilate in Warmblood horses

Calcium dobesilate has recently been used for treating lameness in horses because it enhances microvascular processes and reduces intraosseous pressure. Lameness caused by disorders in bone metabolism and increased intraosseous pressure, such as navicular disease, osseous cyst-like lesions and pedal bone oedema, are commonly treated with rest, anti-inflammatory agents and surgery. Calcium dobesilate has the potential to influence the pathophysiology of these diseases, thereby improving healing. To determine whether calcium dobesilate and its acting agent calcium 2,5-dihydroxybenzene sulfonate (2,5HBSA) is absorbed by the equine gastrointestinal system to generate detectable plasma concentrations. The study was designed as a prospective in-vivo study. Eight healthy adult Swiss Warmblood horses were used in the study. Calcium dobesilate (3 mg/kg, PO, q12h) was administered orally in mash for seven days. Blood samples were collected from a jugular vein after the last dose of calcium dobesilate. All horses underwent daily physical examination and haematological and blood chemical analyses before and after the study. Liquid chromatography was used to determine plasma concentrations of 2,5HBSA. Noncompartmental analysis was used to estimate the pharmacokinetic parameters. 2,5HBSA was detected in plasma samples after oral administration and ranged from 2300 ng/ml to 3600 ng/ml with a mean of 2900 ng/ml. The results of haematological and plasma biochemical testing were within the reference limits at all times, and no adverse effects occurred. Only plasma samples were analysed and calcium dobesilat was only measured after the treatment period of seven days. Calcium dobesilate was absorbed by the equine gastrointestinal system and reached detectable plasma concentrations.