A comparison of the pharmacological activity in cows of two suspensions of betamethasone alcohol.
The activity of two betamethasone (BM) suspensions, which differed only in their solids:vehicle ratio, was examined in cattle. Two groups of 10 cows received by subcutaneous injection either 20 ml of a 2 mg/ml aqueous suspension of BM alcohol or 2 ml of a 20 mg/ml aqueous suspension. A further 10 cows served as a saline-treated control group. The mean peak plasma BM concentration was significantly higher in cows treated with 2 mg/ml suspension. However, plasma BM levels tended to be maintained for longer by the 20 mg/ml suspension. A depression of early morning cortisol levels, similar to that seen with other synthetic glucocorticoids, was recorded with both BM preparations; the depression outlasted the presence of BM. Plasma glucose levels and circulating neutrophil numbers were elevated by BM treatment, and the magnitude and duration of these changes was related to the solids:vehicle ratio of the injected suspensions. The more concentrated suspension was absorbed more slowly and thus produced effects of greater duration.
MacDiarmid
S C
SC
Department of Veterinary Clinical Sciences, Massey University, Palmerston North, New Zealand.
Cooper
B S
BS