Pharmacology of a 40 IU/ml porcine lente insulin preparation in diabetic cats: findings during the first week and after 5 or 9 weeks of therapy

Abstract

The aim of this study was to measure the pharmacokinetics and pharmacodynamics of subcutaneously injected 40 IU/ml porcine lente insulin preparation (Caninsulin, Intervet BV, The Netherlands) in diabetic cats. The pharmacological properties of the insulin in poorly controlled or untreated cats were compared with those after several weeks of treatment, to determine if improved diabetic stability altered the pharmacology of this insulin. In addition, the pharmacological properties of intravenously injected 100 IU/ml regular porcine insulin (Actrapid MC, NovoNordisk, Denmark) were measured. Serial plasma samples were collected after subcutaneous injection of porcine lente insulin from 25 diabetic cats in the first week of admission to a 12-month diabetic treatment trial. Samples were also collected after 4 or 8 weeks of treatment, in those cats which had not achieved diabetic remission by this time. At this time, serial plasma samples were also collected from these cats after intravenous injection of porcine regular insulin. Plasma samples were assayed for glucose, anti-insulin antibodies were extracted using a PEG technique, and samples were assayed for insulin using an RIA kit with low sensitivity for endogenous feline insulin, but high sensitivity for exogenous porcine insulin in feline plasma. Caninsulin injected subcutaneously in diabetic cats led to a peak insulin concentration in plasma after 1.7+/-0.1 h, and a nadir of blood glucose after 4.1+/-0.3 h. Insulin and glucose concentrations returned to baseline within 12 h. There was no significant change in the onset or duration of Caninsulin action between the first week of treatment and 5 or 9 weeks of treatment. Actrapid MC injected intravenously had a peak insulin at 0.36+/-0.03 h, and a nadir of blood glucose at 1.9+/-0.3 h. Insulin and glucose returned to baseline within 6 h. It was concluded that Caninsulin injected subcutaneously has suitable pharmacological properties for the twice-daily treatment of diabetes mellitus in cats. In addition, Actrapid MC insulin injected intravenously has suitable pharmacological properties for injection every 4-6 h in diabetic cats.

Fig 1.

Typical plasma insulin and glucose concentrations in a diabetic cat (cat 1, week 1) after subcutaneous injection of Caninsulin at time=0.