Deposition of insulin powders for inhalation in vitro and pharmacodynamic evaluation of absorption promoters in rats.

AIM

To prepare insulin powder for inhalation by spray-drying technology, determine the deposition of the insulin powder formulation in vitro and preliminarily investigate hypoglycemic response of the dry powder with/without absorption promoters.

METHODS

The depositions of the insulin powder for inhalation were determined by the China Pharmacopoeia 2000 version addenda XH and hypoglycemic effects were evaluated by testing serum glucose with glucose oxidase-peroxidase (GOD-PAP) method.

RESULTS

The depositions of the spray-dried insulin powder for inhalation were more than 40% under various humidity and their changes were not significant when air flow was no less than 18 L x min(-1). The coadministration of insulin with 8 mmol x L(-1)/dose sodium taurocholate [PA = 59.91%, Cnadir = (33 +/- 6) %] and 10 mmol x L(-1)/dose sodium deoxycholate [PA = 47.46% , Cnadir = (32 +/- 7)%] induced a significantly greater decline in blood glucose levels, while coadministration with 1% sodium caprylate, 1% sodium dodecyl sulfate, 250 microg/dose lecithin, 10 mmol x L(-1)/dose EDTA appeared to have no significant effect (P > 0.05).

CONCLUSION

Insulin powder for inhalation was relatively stable under various humidity conditions and different flow current. The use of 8 mmol x L(-1)/dose sodium taurocholate and 10 mmol x L(-1)/dose sodium deoxycholate could be able to potentially improve the bioavailability of insulin by pulmonary route.