Insulin delivery by zinc calcium phosphate ceramics

Zinc-calcium-phosphorous oxide (ZCAP) ceramics were developed to deliver insulin in vivo in rats. Thirty-nine Sprague-Dawley male albino rats (Holtzman Co., Madison, WI), weighing 260 +/- 15 g each, were randomly distributed into six groups: normal controls (3), sham controls (3), diabetic controls (6) and three diabetic experimental groups each consisting of nine rats. Diabetes was induced in rats by an intravenous injection of Streptozotocin (75 mg/kg body weight). Rats in the three diabetic experimental groups were implanted subcutaneously with two ZCAP capsules, each containing 10, 15, or 20 mg of insulin. Blood glucose measurements were taken at least twice a week over a six week period. Plasma insulin levels were measured at two, four, and six weeks by a radioimmunoassay using 125I labeled insulin. Normoglycemia was maintained for three weeks in rats implanted with ZCAP capsules containing a total of 20 mg of insulin. Plasma insulin levels correlated with the normal blood glucose levels in these rats. Thus, ZCAP capsules could be used to deliver insulin and maintain normoglycemia in diabetic rats.