Journal
BIOMATERIALS
Volume 32, Issue 10, Pages 2673-2682Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.biomaterials.2010.12.044
Keywords
Oral delivery; Chitosan; Biodistribution; Pharmacodynamics; Pharmacokinetics; Insulin secretion
Funding
- National Science Council [NSC 98-2120-M-007-007]
- Chang Gung Memorial Hospital, Taiwan, Republic of China [CMRPG340193]
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Exendin-4 is a potent insulinotropic agent in diabetes patients; however, its therapeutic utility is limited due to the frequent injections required. In this study, an orally available exendin-4 formulation, using an enteric-coated capsule containing pH-responsive NPs, was developed. Following oral administration of I-123-labeled-exendin-4 loaded NPs in rats, the biodistribution of the administered drug was investigated using a dual isotope dynamic SPECT/CT scanner. The results showed that the radioactivity of I-123-exendin-4 propagated from the esophagus, stomach, and small intestine and then was absorbed into the systemic circulation; with time progressing, 123I-exendin-4 was metabolized and excreted into the urinary bladder. In the in vivo dissolution study, it was found that the enteric-coated capsule remained intact while in the stomach; the capsule was completely dissolved in the proximal segment of the small intestine and the loaded contents were then released. Oral administration of the capsule containing exendin-4 loaded NPs showed a maximum plasma concentration at 5 h after treatment; the bioavailability, relative to its subcutaneous counterpart, was found to be 14.0 +/- 1.8%. The absorbed exendin-4 could then stimulate the insulin secretion and provide a prolonged glucose-lowering effect. The aforementioned results suggest that the orally available exendin-4 formulation developed warrants further exploration as a potential therapy for diabetic patients. (C) 2011 Elsevier Ltd. All rights reserved.
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