title: Effective oral delivery of insulin in animal models using vitamin B12-coated dextran nanoparticles.
abstract: The potential utility of vitamin B12 carrier system for the oral delivery of conjugated peptides/proteins and enhancement of nanoparticles (NPs) transport has been demonstrated. The present study aims to optimize the effectiveness of VB12-NPs conjugates using different levels of cross-linking, linked with different VB(12)-coatings and evaluates in animal models to investigate an efficient insulin carrier. Amino alkyl VB12 derivatives suitable for oral delivery were synthesized at 5'hydoxy ribose and e-propionamide sites via carbamate and ester/amide linkages, and were coupled to succinic acid modified dextran NPs of varied cross-linking. VB12 binding was confirmed by XPS analysis, and was quantified by HPLC (4.0 to 5.7% w/w of NPs). These polydisperse NPs conjugates showed higher size, high insulin entrapment and faster insulin release with low levels of cross-linking. These VB12-NPs conjugates (150-300 nm) showed profound (70-75% blood glucose reductions) and prolonged (54 h) anti-diabetic effects with biphasic behaviour in STZ diabetic rats. NPs with the low levels of cross-linking were found to be superior carriers, and were more effective with VB12 derivatives of carbamate linkage. The pharmacological availability relative to SC insulin was found to be 29.4%, which was superior compared to NPs conjugate of ester linked VB12 (1.5 fold) and relatively higher cross-linked particles (1.1 fold). Further, the NPs carrier demonstrated a similar oral insulin efficacy in congenital diabetic mice (60% reduction at 20 h). Significant quantities of plasma insulin were found in both animal models (231 and 197 muIU/ml). At two investigated doses, the carrier system shows dose response. Pre-dosing with a large excess of free VB12 minimized the observed activity, indicating predominance of VB12 mediated uptake. It is concluded that VB12-dextran NPs conjugate is a viable carrier for peroral insulin delivery to treat diabetics.
authors: Pharmacology Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad AP, India.
authors: Kishore B
authors: KB
authors: Chalasani
authors: Gregory J
authors: GJ
authors: Russell-Jones
authors: Akhlesh K
authors: AK
authors: Jain
authors: Prakash V
authors: PV
authors: Diwan
authors: Sanjay K
authors: SK
authors: Jain
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects; D002626:Chemistry, Pharmaceutical; D003432:Cross-Linking Reagents / Q000737:chemistry; D003911:Dextrans / Q000737:chemistry*; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D004337:Drug Carriers; D004339:Drug Compounding; D004811:Epichlorohydrin / Q000737:chemistry; D005260:Female; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics; D007328:Insulin / Q000008:administration & dosage* / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics; D051379:Mice; D016688:Mice, Inbred NOD; D053758:Nanoparticles; D010316:Particle Size; D051381:Rats; D017208:Rats, Wistar; D012995:Solubility; D013045:Species Specificity; D014805:Vitamin B 12 / Q000031:analogs & derivatives / Q000138:chemical synthesis*
chemical_list: D001786:Blood Glucose; D003432:Cross-Linking Reagents; D003911:Dextrans; D004337:Drug Carriers; D007004:Hypoglycemic Agents; D007328:Insulin; D004811:Epichlorohydrin; D014805:Vitamin B 12