In vitro characteristics of an insulin suppository developed using palm oil base (HAMIN®) and its hypoglycaemic effect on rabbits

Abstract

The long-term administration of insulin requires the development of new delivery routes. Using a base developed in-house, called HAMIN®, an insulin suppository containing 100 units (U) of insulin was formulated. The suppository was subjected to stability testing at various temperatures and the assay value was monitored. Other physical factors such as hardness, disintegration time, thermal analysis and dissolution were also tested. The suppository released more than 80% of its drug content in 30 min, and was stable for up to 11 months at −20°C. The suppository effect was studied on 11 New Zealand white rabbits, with body weight ranging from 1.6 to 2.1 kg. The results show that there was a marked reduction in glucose content when the suppository was inserted. The average drop in glucose content was 2.7 mmol/L in 15 min from the time of insertion. The maximum drop in glucose content reached 3.9 mmol/L in 2 h. Plasma insulin level, quantified using an enzyme-linked immunosorbent assay, showed a value of more than 100 µIU insulin/ml blood after 30 min. Although the insulin bioavailability was expectedly low, the rate at which the hypoglycaemic effect took place and the percentage of glucose reduction were comparable to results after subcutaneous injection.