Release profile of insulin from pH-sensitive hydrogel and its hypoglycemic effect by oral administration

Abstract

The purpose of this study was to investigate the release profile and in vivo hypoglycemic effect of insulin (INS)-loaded pH-sensitive hydrogel (INS-TPM950) administrated by oral route. TPM950 was fabricated via a free polymerization method and its inner morphology was observed with a scanning electron microscope (SEM). INS was encapsulated into TPM950 by an adsorption method, and the in vitro release profiles of INS from INS-TPM950 were revealed in pH 1.2 and 6.8. To investigate the hypoglycemic effect of INS-TPM950, Male Wistar rats were used in modeling of diabetes mellitus by multiple intraperitoneal injection of alloxan. The in vivo hypoglycemic effect of oral INS-TPM950 was studied, and the optimal dosage was also determined. SEM photograph showed that abundant 3D meshes were distributed in the inner of TPM950 hydrogel. INS release profile suggested that only 18.2 ± 11.3% INS was released in pH 1.2, but over 88.8 ± 4.9% was delivered into phosphate buffer solution in pH 6.8. After injection to the diabetic rats, the released INS solution from INS-TPM950 exhibited an obvious hypoglycemic effect. Oral administration of 50.0 I.U./kg of INS-TPM950 showed a slow but effective hypoglycemic effect, and the lowest blood glucose level was reached to 47.5 ± 5.5% of the original level. Therefore, this formulation had a potential application in diabetes treatment via oral ingestion.

Keywords:

• Insulin
• diabetes
• alloxan
• oral administration
• blood glucose level

Funding

This work was supported by Scientific Research Fund of Xinxiang Medical University [2014QN147].

Disclosure statement

No potential conflict of interest was reported by the authors.