RESEARCH ARTICLE e-ISSN: 2249-622X * Corresponding author: Manoj Gadhvi | Faculty of Pharmaceutical Sciences, Jodhpur National University, Jodhpur, India| Email: desaiurvish@gmail.com Page15 Page15 Simultaneous Determination of Ritonavir and Atazanavir in Combined Tablet Dosage Form by HPTLC Manoj Gadhvi, 1* Anil Bhandari, 1 Bhanubhai Suhagia, 2 Ishwarsinh Rathod, 2 Urvish Desai, 2 Arpit Patwari, 2 Ketan Variya 2 1 Faculty of Pharmaceutical Sciences, Jodhpur National University, Jodhpur, India. 2 Department of Quality Assurance, L. M. College of Pharmacy, Ahmedabad - 380009, India. ABSTRACT A new, simple, sensitive, precise and accurate High-performance thin-layer chromatographic method for simultaneous determination of Ritonavir and Atazanavir in their combined tablet dosage form has been developed, validated and used for determination of the compounds in commercial pharmaceutical products. Chromatographic separation was achieved on aluminium plates precoated with silica gel 60 F 254 as the stationary phase and chloroform: ethyl acetate: acetone (5:2:3, v/v/v) as a mobile phase. Densitometric measurements of their spots were achieved at 244 nm over the concentration ranges of 800-2800 ng spot -1 and 2400-8400 ng spot -1 , with mean recoveries of 98.57 ± 0.35 and 99.16 ± 0.20 for ritonavir and atazanavir respectively. Limit of detection for ritonavir and atazanavir were found to be 300 ng spot -1 and 200 ng spot -1 respectively. Keywords: High-performance thin-layer chromatography, Ritonavir, Atazanavir. 1. INTRODUCTION Ritonavir (RTV) chemically (5S,8S,10S,11S)-10-hydroxy-2- methyl-5-(1-methylethyl)-1-[2-(1-methylethyl)-4- thiazolyl]-3,6-dioxo-8,11-bis(phenylmethyl)-2,4,7,12- tetraazatridecan-13-oic acid 5-thiazolyl methyl ester. Atazanavir (ATV) chemically (3S,8S,9S,12S)-3,12-Bis(1,1- dimethylethyl) -8-hydroxy-4,11-dioxo-9-(phenyl methyl)- 6-[[4-(2-pyridinyl)phenyl]methyl]-2,5,6,10,13-penta aza tetradecanedioic acid dimethyl ester, sulphate (1:1). Ritonavir and Atazanavir inhibit HIV protease, enzyme required to form functional proteins in HIV infected patients. Ritonavir is available in combination of Atazanavir, which inhibits the CYP3A4-mediated metabolism of Lopinavir, increasing the Atazanavir concentrations [1-2]. Literature review reveals that methods have been reported for analysis of RTV and ATV in pharmaceutical formulations and in human plasma individually or in combination with other antiviral drugs using liquid chromatography (LC) [3-14], thin layer chromatography (TLC) [15] and UV spectroscopy [16-19] and LC/MS [20- 22].As per literature review, there is no single HPTLC method has been reported for simultaneous determination of RTV and ATV in combination tablets. Hence, aim of the present study to develop and validate accurate method and determine both drugs concurrently by simple, rapid, and selective HPTLC method that could be used for quality control and routine analysis. The proposed method was validated in accordance with International Conference on Harmonization (ICH) guideline [23]. 2. EXPERIMENTAL Materials and Reagents RTV and ATV powders were procured from Hetero Drugs Ltd. (Hyderabad, India). VIRATAZ-R Tablets was manufactured by Hetero Drugs Ltd. Each tablets claimed to contain 100 mg RTV and 300 mg ATV. Methanol was purchase from Loba Chemie (Mumbai, India). Toluene and Chloroform were purchased from Rankem (RFCL Ltd., 4 th Dec 2012 Received in revised form: 18 th Dec 2012 Accepted: 20 th Dec 2012 Available online: 15 th Jan 2013 Online ISSN 2249–622X http://www.jbiopharm.com