Formulation of Powder Dosage Form of Insulin for Intranasal Delivery

Aims: To develop a powder dosage form of insulin for intranasal administration and investigate its glucose- lowering effect in albino rabbits. Methods: Nine different powder formulations, each containing 500 mg powder equivalent to 50 IU of insulin were prepared by adsorbing soluble insulin solution mixed with varying amounts of polysorbate 80, guar gum and porcine mucin on to microcrystalline cellulose (MCC) powder by solvent evaporation. The formulations were subjected to in vitro release studies, from which two optimized formulations (E and H) were further evaluated in vivo for their glucose lowering effect in albino rabbits via the intranasal route. Results: All the formulations released > 90% of insulin within 30 min in the in vitro release studies. Formulations E and H containing 0.1% Tween 80 and either guar gum or mucin gave the highest drug release of 85% each in 15 min and were selected for the in vivo studies. In vivo results obtained after 30 and 60 min of intranasal administration showed a reduction of 30 and 15% in blood glucose level for formulation E and 40 and 30% for formulation H as against the subcutaneously administered insulin (control) with 51 and 46% reduction respectively. There was no significant difference (p > 0.05) between the control and the formulations with regard to their glucose-lowering effect. Conclusion: The results of the study showed that the insulin powder dosage form prepared with MCC for intranasal delivery achieved a moderate reduction in blood glucose level in rats via the intranasal route, indicating the formulations can be further developed to achieve enhanced insulin administration.