Journal of Applied Solution Chemistry and Modeling, 2013, 2, 145-157 145 E-ISSN: 1929-5030/13 © 2013 Lifescience Global Improvement of Dissolution Rate of Chlorzoxazone by Solid Dispersion Technique and Development of Buccal Patch Swati Jagdale * , Asawaree Hable, Aniruddha Chabukswar and Bhanudas Kuchekar MAEER’s Maharashtra Institute of Pharmacy, S. No. 124, MIT Campus, Paud Road, Kothrud, Pune-411038, India Abstract: Chlorzoxazone (CLZ) is insoluble in water. Its half life is 1.1 hr, dose is 250 mg and has first pass metabolism. Formation of solid dispersions of CLZ with pluronic F127 will enhance the bioavailability of the drug. Phase-solubility studies revealed AL type of curves, indicating the ability of pluronic F127 to disperse with CLZ and significantly increase in solubility. The solid dispersions of CLZ was carried out with pluronic F127 by different methods and characterized by in vitro drug release, drug content, FTIR, DSC, XRD. All the solid dispersions showed dissolution improvement compare to pure drug. These techniques revealed distinct loss of drug crystallinity in the formulation accounting for enhancement in dissolution rate. The stability study for solid dispersions indicated, all formulations were stable. Methods showing best in vitro drug release profile were selected in further development of mucoadhesive buccal patches. A buccal patch has been developed using mucoadhesive polymers HPMC K4M and carbapol 974. The developed patches were evaluated for the physicochemical, mechanical and drug release characteristics. The optimized patches showed good mechanical and physicochemical properties to withstand environment of oral cavity. The in-vitro permeation study showed that patches could deliver drug to the oral mucosa for a period of 8 hrs. The results indicate that suitable bioadhesive buccal patches with good permeability could be prepared. The batches FH4 and FC4 showed 79.65% and 79.93% permeated through goat mucosa membrane in 8 hrs. The stability study for buccal patch revealed that all batches were stable. Keywords: Solid dispersions, pluronic F127, chlorzoxazone, dissolution studies, buccal patch. 1. INTRODUCTION The poor solubility of drug (BCS Class II) in gastrointestinal fluid gives rise to variations in dissolution rate and incomplete bioavailability. An improvement of the dissolution rates of water-insoluble drugs is one of the most challenging and important tasks of drug development as it can increase drug bioavailability [1-3]. Chemically, Chlorzoxazone (CLZ) is 5-chloro-3H-benzooxazol-2-one, which belongs to skeletal muscle relaxant (centrally acting) class. It has half life of 1.1 hours & dose is 250mg. It is soluble in methanol, ethanol & isopropanol; freely soluble in aq. solutions of alkali hydroxides and slightly soluble in water. It is necessary to improve the dissolution rate of CLZ to enhance the bioavailability [4-5]. There are different chemical or formulation approaches to improve drug dissolution and bioavailability. Among the various strategies solid dispersion technique has often proved to be the most successful in improving the dissolution and bioavailability of poorly soluble drug. There are different methods for preparation of solid dispersion. Solid dispersion is most successful technique as it is simple, economic, and advantageous to enhance dissolution rate [6-13]. *Address correspondence to this author at the Department of Pharmaceutics, MAAER’s Maharashtra Institute of Pharmacy, S. No. 124, MIT Campus, Ex- serviceman Colony, Paud Road, Kothrud, Pune-411038, India; Tel: +91- 9881478118; E-mail: jagdaleswati@rediffmail.com Buccal delivery of drugs provides an attractive alternate to the oral route of drug administration, particularly in overcoming deficiencies associated with the latter mode of dosing. Problems such as high first pass metabolism and drug degradation in gastrointestinal environment can be circumvented by administering the drug via the buccal route. It is also possible to administer drugs to patients who cannot be dosed orally. Therefore, adhesive mucosal dosage forms were suggested for oral delivery that included adhesive tablets adhesive gels and adhesive patches. However, buccal patches are preferable over adhesive tablets in terms of flexibility and comfort. Now day’s bioadhesive polymers received considerable attention as platforms for buccal controlled delivery due to their ability to localize the dosage form in specific regions to enhance drug bioavailability. In order to prepare films having the appropriate characteristics, film-forming polymers were initially used alone and successively in combination with mucoadhesive polymers. The patches with the best characteristics were selected for testing. The plasticizer interposes itself between the polymer chains and interacts with the forces held together by extending and softening the polymer matrix. The commonly used plasticizers include phthalate esters, phosphate esters, fatty acid esters and glycol derivatives [14-19]. The solid dispersion showing best in vitro drug release profile can be selected in further development of buccal patches of CLZ. This would help to facilitate