Pharmacodynamic properties: Prednisolone is an intermediate acting corticosteroid having about 4 times the anti-inflammatory activity and about 0.8 times the sodium-retaining effect of cortisol. Corticosteroids suppress the immune response by inhibition of dilatation of capillaries, migration and function of leucocytes and phagocytosis. Glucocorticoids have an effect on metabolism by increasing gluconeogenesis. Where medical treatment of horses with RAO (severe asthma) is required, glucocorticoids are effective in controlling clinical signs and decreasing neutrophilia in airways.

Pharmacokinetic particulars: Following oral administration in horses prednisolone is readily absorbed giving a prompt response which is maintained for approximately 24 hours. The overall average Tmax is 2.5 ± 3.1 hours, Cmax is 237 ± 154 ng/ml and AUCt is 989 ± 234 ng·h/ml. T1/2 is 3.1 ± 2.3 hours. Bioavailability after oral administration is about 60%. Partial metabolism of prednisolone to the biologically inert substance prednisone takes place. Equal amounts of prednisolone, prednisone, 20β-dihydroprednisolone and 20β-dihydroprednisone are found in urine. Excretion of prednisolone is complete within 3 days. Multiple dosing does not result in plasma accumulation of prednisolone.