[Bovine and rat albumin used as a biodegradable matrix for the slow release of insulin]. / Albúmina bovina y de rata usada como una matriz biodegradable para la liberación lenta de insulina.

The daily treatment of insulin-dependent diabetes includes one or several insulin injections per day. About 50 years ago non-hormonal molecules were added to insulin in order to enhance its half life. In this report albumin microspheres, serving as a matrix for crystalline insulin, were used for delivery of insulin. They were implanted in a group of rats with alloxan-induced diabetes. Body weight, plasma glucose and insulin were measured at periodic intervals. The stability, bacterial purity and pyrogenicity of the microspheres were tested. Five days after the microspheres were implanted the mean concentrations of glucose (32.9 vs 5.7 nMol/L) and insulin (2.9 vs 20.2 microU/mL) and the body weight (217 vs 250 g) returned to values comparable to those in the non-diabetic state. They remained stable for 15 days; afterwards, glucose increased and the latter two decreased: all became abnormal 20 days after implantation. When the microspheres were implanted on three occasions in the same animal at 15 days intervals, glucose and insulin concentrations and body weight remained within the limits observed in 100 non-diabetic rats, and no antibodies against albumin or insulin were detected.