Research J. Pharm. and Tech. 6(8): August 2013 905 ISSN 0974-3618 www.rjptonline.org RESEARCH ARTICLE Extractive Spectrophotometric Method for the Determination of Metaxalone in Bulk and its Pharmaceutical Formulation K. Sundar Babu 1 , P. Kareemulla 1 , N. V. Mahipal Reddy 1 , B. Mohammed Ishaq 1 *, N. Bharathi Natarajan 2 , M. Madhu 1 , Chakka Gopinath 1 1 Department of Pharmaceutical Analysis & Quality assurance, Annamacharya College of Pharmacy, Rajampet, A.P 2 Chaavan College of Pharmacy, Nellore, A.P *Corresponding Author E-mail:- bmdishaq@yahoo.com ABSTRACT: Metaxalone, a muscle relaxant used to relax muscles and relieve pain caused by strains, sprains and other musculoskeletal conditions a simple, sensitive, rapid and cost effective extraction spectrophotometric method was described for the assay of Metaxalone in bulk samples and pharmaceutical formulations. The method was based on the formation of chloroform soluble ion-pair complexes of Bromophenol blue with Metaxalone, formed pink colored chromogen in a phosphate buffer of pH 4 with absorbance maximum at 630nm. The developed spectrophotometric method was validated in accordance with ICH guidelines. Linearity of the method was found to be 10-50μg/ml and obeyed Beer’s law. The LOD and LOQ were found to be 0.6757g/ml and2.389g/ml respectively. The results of analysis for the method have been validated statistically and by recovery studies. The proposed method was simple, sensitive, accurate and suitable for quality control applications. KEYWORDS: Metaxalone, muscle relaxant, bromo phenol, method validation, UV- Spectroscopy INTRODUCTION: Metaxalone is a muscle relaxant used to relax muscles and relieve pain caused by strains, sprains, and other musculoskeletal conditions. Chemically metaxalone is 5- [(3, 5-dimethylphenoxy) methyl]-1, 3-oxazolidin-2-one (Figure 1) 1 . It is a white to almost white, odorless crystalline powder freely soluble in chloroform, soluble in methanol, 96% ethanol, and deionized water and in propylene glycol, but practically insoluble in ether and water 2 . Metaxalone has no direct action on the contractile mechanism of striated muscle, the motor end plate, or the nerve fiber. There is very limited or inconsistent data regarding the effectiveness and safety of metaxalone 3 . Metaxalone is one of the commonly used muscle relaxant therapies for acute low back pain 4 . Fig. 1: Chemical Structure of Metaxalone Received on 25.04.2013 Modified on 11.05.2013 Accepted on 16.05.2013 © RJPT All right reserved Research J. Pharm. and Tech. 6(8): August 2013; Page 905-907 Literature survey carried out revealed that several methods have been reported for estimation of metaxalone by using, , RP-HPLC Method 5,6 , HPLC 7 , RP-UPLC Method 8 , LC-MS Method 9 , UV spectrophotometric method 10 , UV Derivative spectrophotometric method, HPTLC Method are available to determine metaxalone in tablet dosage form. However, there is no method reported for estimation of metaxalone in tablet dosage form by using visible spectroscopy. MATERIALS AND METHODS: Instrumentation: A Shimadzu UV –Visible spectrophotometer model 1800 with 1cm matched quartz cells were used for measuring the absorbance. Chemicals and reagents: Metaxalone pure drug was obtained as a gift sample from MSN Labs, Hyderabad. Tablets of 400mg strength were procured from the local market under the commercially available brand name Skelaxi. All the chemicals such as methanol, bromophenol blue, phosphate buffer p H 4 and chloroform used were of analytical grade.