FORMULATION AND EVALUATION OF A CHITOSAN-PVA-GELLAN INSULIN IMPLANT Original Article SATISH C. S. a Received: 13 Jan 2017, Revised and Accepted: 17 Apr 2017 Department of Pharmaceutics, PES College of Pharmacy, 50 Feet Road, Hanumanthanagar, Bengaluru 570050, India Email: satishcs@hotmail.com ABSTRACT Objective: The purpose of this study was to ascertain the applicability of degradable materials for fabrication of an insulin release system. Methods: Insulin implants were prepared by using poly (vinyl alcohol) (PVA), gellan and chitosan by solution casting method. The prepared implants were evaluated for swellability, content uniformity, potency and purity of insulin in implants, scanning electron microscopy studies, in vitro release studies, in vitro degradation studies using lysozyme, stability studies and circular dichroism spectroscopy. Results: The swelling degree of the implants was found to be in the range of 1.07-1.56. The diffusion coefficient of water through the implant was found to depend on the calcium chloride (CaCl 2) concentration. The diffusion coefficient of insulin through the chitosan-PVA-gellan in the early stages was found to be in the range of 1.99×10 -5 cm 2 /sec to 5.24×10 -5 cm 2 /sec and at later stages in the range of 6.9×10 -6 cm 2 /sec to 1.10×10 -5 cm 2 /sec. The weight of the implants was 48±0.58 mg. The insulin content in the implants was 9.86±0.10 mg. The potency of insulin extracted from the implants was 27.11±0.75 U/mg or 95.12±2.61 % of the control insulin. The in vitro release studies showed that insulin was released completely in a period of 13-19 d depending on the composition of the implant. The increase in CaCl 2 Conclusion: These studies provide validity for the potential utility of chitosan-PVA-gellan implant systems for the delivery of insulin. The studies also demonstrate that insulin maintained its integrity within the implant system. Implants showed the complete release of insulin in 19 d and the release of insulin from the implants depended on the amount of CaCl retarded the rate of insulin release whereas the increase in PVA content leads to the rapid release of insulin. The device was found to undergo significant weight loss due to enzyme mediated degradation. 2 Keywords: Insulin, Degradation, Diffusion, Gellan, Chitosan . © 2017 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/) DOI: http://dx.doi.org/10.22159/ijap.2017v9i3.17074 INTRODUCTION Diabetes mellitus refers to a group of metabolic diseases characterised by chronic hyperglycemia, due to defects in insulin secretion. The treatment of diabetes by insulin injection provides only a poor approximation of normal glucose homoeostasis, especially for insulin- dependent diabetes where blood glucose concentrations vary widely despite insulin therapy [1, 2]. This is because the pharmacokinetics of insulin following subcutaneous injection does not match the profiles of physiological insulin secretion [3, 4]. Moreover, subcutaneous injections result in localized insulin deposits that lead to local hypertrophy and fat deposits under the skin. Together these disadvantages lead to suboptimal pharmacodynamics properties of the applied insulin, which does not allow mimicking the complex physiological insulin secretion pattern [5]. Polymeric implants are one of the promising devices for protein drug delivery. Some polymeric matrices can protect drugs from physiological conditions that could degrade the proteins. Therefore, a lot of research is ongoing to identify appropriate polymer systems to formulate ideal protein drug delivery systems that would allow ease of incorporation of protein drugs without affecting their bioactivity, deliver them at the desired rate and exhibit biocompatibility when in contact with the tissue [6]. Gellan is an anionic polysaccharide of microbial origin, which is capable of forming a three-dimensional network by complexation with cations and hydrogen bonding with water. The apparent viscosity of gellan gum dispersions can be markedly increased by increasing both pH and cation concentration [7]. Furthermore, its ingestion has never produced reported adverse dietary, physiological or toxic effects in animals and humans. These properties make this polysaccharide suitable for several commercial applications, such as in the food industry and in drug delivery [8]. While gellan gum has never been used to deliver biologically active macromolecules, it has some potential for this application. The ion- induced cross-linking property of gellan avoids the presence of initiator or organic cross-linker that can be toxic to the protein activity if not removed from the device. The preparation also does not need to involve organic solvents and/or high temperatures that could denature the protein. Polyvinyl alcohol (PVA) is one of the hydrogels often used in biomedical applications [9]. It is a water-soluble synthetic polymer with excellent film forming, emulsifying and adhesive properties. Chitosan forms a polyionic complex with gellan and this property was used in the current work to prepare an insulin implant of chitosan-PVA-gellan for maintenance of prolonged therapeutic levels of insulin. The objective of this investigation was to develop a chitosan-PVA- gellan implant device as an implant for insulin delivery. The procedure for the preparation of chitosan-PVA-gellan implant was optimized. The swelling index and in vitro release characteristics for drug delivery were investigated. MATERIALS AND METHODS Materials Gellan, polyvinyl alcohol (average molecular weight range 1,20,000– 1,80,000 and degree of hydrolysis 99%), Chitosan (medium molecular weight, 75-85% deacetylated), insulin (porcine pancreas) were purchased from Sigma, St. Louis, MO, USA. Lysozyme (HiMedia 50,000 U/mg), Calcium chloride (CaCl 2 Preparation of chitosan-PVA-gellan insulin implant ), potassium dihydrogen phosphate, sodium hydroxide and sodium chloride were obtained from SISCO Scientific Laboratories, Mumbai India. The compositions of various formulations are given in table 1. A 0.5% w/v chitosan solution in 0.2 M acetic acid was poured into a glass mold (Area 28.3 cm 2 ) and dried at 25 °C under vacuum for 48 h. PVA was dissolved in water by heating to 90 °C, to which gellan and glycerin (2% v/v) were added and stirred until a clear solution was obtained. To this solution, insulin dissolved in small volume of 0.1 N HCl and diluted with pH 7.4 phosphate buffered saline (PBS) was added at 25 °C and stirred gently [9]. The solution was then poured over the chitosan film in a glass mould and dried at 25 °C under vacuum for 24 h. Over this layer 10 ml of 0.5%, w/v of chitosan was poured and was allowed to dry at 25 °C under vacuum. The dry formulations were cut into 10 mm circular discs. International Journal of Applied Pharmaceutics ISSN- 0975-7058 Vol 9, Issue 3, 2017