Hindawi Publishing Corporation BioMed Research International Volume 2013, Article ID 178973, 8 pages http://dx.doi.org/10.1155/2013/178973 Research Article Development and Characterization of Novel Polyurethane Films Impregnated with Tolfenamic Acid for Therapeutic Applications Hilal Istanbullu, Sofia Ahmed, Muhammad Ali Sheraz, and Ihtesham ur Rehman Department of Materials Science and Engineering, he Kroto Research Institute, University of Sheffield, North Campus, Broad Lane, Sheffield S3 7HQ, UK Correspondence should be addressed to Ihtesham ur Rehman; i.u.rehman@sheield.ac.uk Received 12 April 2013; Accepted 29 July 2013 Academic Editor: Ren´ e Holm Copyright © 2013 Hilal Istanbullu et al. his 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. he present study deals with the preparation of polyurethane (PU) ilms impregnated with a nonsteroidal anti-inlammatory drug, tolfenamic acid (TA). Solvent evaporation technique has been employed for the preparation of TA-PU ilms in two diferent ratios of 1 : 2 and 1 : 5 in Tetrahydrofuran (THF) or THF-ethanol mixtures. he prepared ilms were characterized using X-Ray Difraction (XRD), Diferential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and release studies. he results indicate transformation of crystalline TA to its amorphous form. he degree of crystallinity changes both by increasing the polymer concentration and solvent used for the ilm preparations. he release proiles of TA were also found to be afected, showing a decrease from approximately 50% to 25% from 1 : 2 to 1 : 5 ratios, respectively. 1. Introduction Polymer ilms are generally used for therapeutic purposes and a number of workers have reported the use of diferent polymeric ilms for the delivery of various therapeutic agents via diferent routes [1–6]. Among the variety of polymers available, polyurethanes (PU) are a family of polymers that are widely used as biomaterials in clinical applications. heir use not only in the medical ield but also in other commercial applications is signiicant in many areas, since their easy structure manipulation allows the control of their chemical, physical, and mechanical characteristics [7–10]. PU are used in a wide range of biomedical applications due to their excellent physical and mechanical properties and relatively good blood compatibility [8–12]. hey also possess great diversity due to their diferent chemical compositions and properties such as elasticity, tolerance in the body, durability, and compliance, which are generally superior to other biomaterial polymers [9, 12–14]. Recently, it has been reported that PU ilms prepared through solvent evaporation technique were efective in the controlled in vitro delivery of curcumin against human lung cancer cells [4]. Polyurethanes are among the many commercially impor- tant classes of polymers. he term “polyurethane” is more one of convenience than of accuracy, since these poly- mers are not derived by polymerising a monomeric ure- thane and are derived from the reaction of cyano (–NCO) and hydroxyl (–OH) groups to form urethane linkage. PU is a class of polymers, which contains a signii- cant number of urethane groups contained within the molecule, although not necessarily repeating in a regular order [11]. A urethane group is formed by the chem- ical reaction between a hydroxyl and isocyanate group (Figure 1(a)). PU contains intermolecular urethane linkages that are formed due to the condensation reaction of polyisocyanates and polyols, and most commonly diisocyanates and diols are used to obtain linear PU. Typically PU possesses three monomers: a diisocyanate, a macroglycol (diol), and a chain extender [7, 10, 13]. Polymeric materials may be dissolved either in pure solvents or in mixtures of diferent solvents. Mixtures are used in order to enhance the solvency power of the primary solvents. Tetrahydrofuran (THF) is found to be one of the best solvents for PU with a polymer interaction parameter value of 0.78 [15]. Tolfenamic acid (2-[(3-chloro-2-methylphenyl)amino]- benzoic acid) (Figure 1(b)) is a nonsteroidal anti-inlamma- tory drug (NSAID) and is used in the treatment of migraine,