International Scholarly Research Network ISRN Pharmaceutics Volume 2011, Article ID 651909, 9 pages doi:10.5402/2011/651909 Research Article Formulation and Evaluation of Transdermal Patch of Repaglinide Shailesh T. Prajapati, Charmi G. Patel, and Chhagan N. Patel Department of Pharmaceutics, Shri Sarvajanik Pharmacy College, Gujarat, Mehsana 384001, India Correspondence should be addressed to Shailesh T. Prajapati, stprajapati@gmail.com Received 15 April 2011; Accepted 17 May 2011 Academic Editors: M. Moneghini and J. Torrado Copyright © 2011 Shailesh T. Prajapati et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Repaglinide has the half life of 1 hour, and bioavailability in the body is 56% due to first-pass metabolism. The total daily dose of Repaglinide is 16 mg (e.g., 4 mg four times daily depending on meal patterns); hence, it required frequent dosing. Transdermal patch of Repaglinide was prepared to sustain the release and improve bioavailability of drug and patient compliance. Different formulations were prepared by varying the grades of HPMC and concentration of PVP K30 by solvent casting method. The prepared formulations were evaluated for various parameters like thickness, tensile strength, folding endurance, % elongation, % moisture content, % moisture uptake, % drug content, in vitro drug release, in vitro permeation, and drug excipient compatibility. A3 2 full factorial design was applied to check the effect of varying the grades of HPMC (X 1 ) and PVP concentration (X 2 ) on the responses, that is, tensile strength, percentage drug released in 1 hr (Q 1 ), 9 hr (Q 9 ), and diffusion coefficient as a dependent variables. In vitro release data were fitted to various models to ascertain kinetic of drug release. Regression analysis and analysis of variance were performed for dependent variables. The results of the F2 statistics between factorial design batches and theoretical profile were used to select optimized batch. Batch F6 was considered optimum batch which contained HPMC K100 and PVP (1.5%), showed release 92.343% up to 12 hr, and was more similar to the theoretical predicted dissolution profile ( f 2 = 69.187). 1. Introduction Transdermal drug delivery system (TDDS) has been an increased interest in the drug administration via the skin for both local therapeutic effects on diseased skin (topical delivery) as well as for systemic delivery of drugs. The skin as a site of drug delivery has a number of significant advantages over many other routes of drug administration, including the ability to avoid problems of gastric irritation, pH and emptying rate effects, avoid hepatic first-pass metabolism thereby increasing the bioavailability of drug, reduce the risk of systemic side effects by minimizing plasma concentrations compared to oral therapy, provide a sustained release of drug at the site of application; rapid termination of therapy by removal of the device or formulation, the reduction of fluctuations in plasma levels of drugs, and avoid pain associated with injections. The transdermal delivery can also eliminate pulsed entry into the systemic circulation, which might often cause undesirable side effects [1]. Diabetes mellitus is a major and growing health problem worldwide and an important cause of prolonged ill health and early death. It is a chronic metabolic disorder character- ized by a high blood glucose concentration (hyperglycemia) caused by insulin deficiency, and it is often combined with insulin resistance [2]. Repaglinide is an oral blood- glucose-lowering drug of the meglitinide class use to treat NIDDM (noninsulin-dependent diabetes mellitus). It lowers blood glucose by stimulating the release of insulin from the pancreas. It has an extremely short half life of 1 h. In addition, the oral bioavailability of Repaglinide is low (56%) due to extensive hepatic first-pass effect. Dosage frequency of Repaglinide is 0.5 to 4mg in 3 to 4 times in a day. It has melting point of 130-131 ◦ C and mol. wt. 452.58 [3–6]. It belongs to class 2 drug. Repaglinide topical preparation may be beneficial to the patient since it reduce adverse effects and avoid the hepatic first-pass metabolism. The need for transdermal delivery of Repaglinide is further justified due to the requirement of maintaining unfluctuating plasma concentrations for effective management of blood sugar for long period in diabetic patients. The purpose of the present work was to develop transder- mal formulation of Repaglinide which increases the patient