Journal of Pharmacy Research Vol.4.Issue 6. June 2011 P. Balanet al. / Journal of Pharmacy Research 2011,4(6),1663-1665 1663-1665 Research Article ISSN: 0974-6943 Available online through www.jpronline.info *Corresponding author. Mr.P.Balan, Assistant Professor, Faculty of Pharmacy, PRIST University, Thanjavur -614904, Tamilnadu, India, Tel.: (0)9698798284 E-mail:balannandu@gmail.com INTRODUCTION Simultaneous estimation of Etodolac and Paracetamol by UV Spectrophotometric method in tablet formulation P.Balan *1 , I. Carolin Nimila 1 , M. Lakshmi Prasanna 1 , M. Vanaja Rani 1 , S. Rajasekar1. Department of Pharmaceutical Analysis, Faculty of Pharmacy, PRIST University, Thanjavur -614904, Tamilnadu, India. Received on: 11-02-2011; Revised on: 16-03-2011; Accepted on:21-04-2011 ABSTRACT A simple, accurate, precise, rapid and economical spectrophotometric method for simultaneous estimation of Etodolac and Paracetamol in combined tablet dosage form has been developed utilizing simultaneous equation method. In this method, absorbance is measured at two wavelengths, one being λmax of Etodolac at 223.5 nm ( λ1) and the other being ?max of Paracetamol 242.5nm ( λ2). Both the drugs obey Beer’s Lambert law in the concentration ranges employed for this method. Result of the method was validated statistically as well as by recovery studies. Proposed method for simultaneous estimation of Etodolac and Paracetamol in combined sample solutions was found to be simple, accurate and reproducible. Once the equations were determined, analysis required only the measurement of the absorbance of the sample solution at the two wavelengths selected, followed by a few simple calculations. It is a novel method that can be employed for routine analysis in quality control. Key words: Etodolac, Paracetamol, Simultaneous equation method, Validation and recovery studies. Fig1: Etodolac Fig2: Paracetamol ABS nm Smooth: 0 Deri.: 0 200 210 220 230 240 250 260 270 280 290 300 310 320 330 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 Fig 3: Overlain Spectrum of Etodolac and Paracetamol (10μg/ml) Table 1: Statistical Parameters from the Calibration Plot: Optical characteristics Etodolac Paracetamol Absorption maxima 223.5nm 242.5nm Beer’s law limit 2-14mcg/ml 2-14mcg/ml Coefficient of correlation 0.9980 0.9984 Slope 9.452235 17.07481 Y-Intercept 0.055 0.025 Molar absorptivity (lit/mole/cm) 1358.5 697.2 Standard deviation 0.456345 0.252825 Paracetamol is chemically N-(4-hydroxyphenyl) acetamide [1, 2]. Etodolac is chemically 1,8-Diethyl-1,3,4,9-tetrahydropyrano (3,4-b)indole-1-acetic acid [3]. Both these drugs belong to class of nonsteroidal anti-inflammatory drugs (NSAIDs). A combination of 500 mg of Paracetamol and 400 mg of Etodolac is available commercially as tablet. This combination is used as analgesic and antipyretic. Only one method has been reported in the literature for the estimation of Paracetamol and Etodolac in combination using methanol as solvent. The present study was aimed at the simultaneous estimation of Paracetamol and etodolac by simultaneous equation using phosphate buffer pH 7.4 as solvent. MATERIALS AND METHODS: Equipments: Instrument used was an UV-Visible double beam spectrophotometer, make: ANALYTICAL Model UV-2310 (Tech comp) with a bandwidth of 1.5nm and a pair of 1 mm matched quartz cells. All weighing was done on Sartorius analytical balance. Calibrated glass wares were used throughout the work. Reagents and Chemicals Gift sample of Paracetamol and etodolac were procured from IPCA, Laboratories Mumbai, India. The commercial fixed dose combination product ETOVA-P tablet (IPCA Laboratories) was procured from the local pharmacy. As we used Phosphate buffer pH 7.4 instead of Methanol by reducing the chemical wastage, chemicals were procured from PRIST University, Thanjavur, Tamilnadu. All the reagents used in this assay were of analytical grade and the reagent’s solution were prepared using pre analysed distilled water. Preparation of Stock Solutions Two series of different concentration in range of 2-14 μg/ml of concentration for Paracetamol and 2-14 μg/ml for Etodolac were prepared from the working standard solutions. The calibration curves were plotted at 242.5nm and 223.5nm. The absorptivities (A 1% 1 cm) of both the drugs at both the wavelength were determined. These calculated values were the mean of six independent determinations. The absorbance and absorptivity value at the DETERMINATION OF ABSORPTION MAXIMA: The standard solution of Etodolac and Paracetamol (10μg/ml) was scanned at different concentrations in range of 200-400nm and the λmax was found to be 223.5nm and 242.5nm against blank. The overlain spectrum of Etodolac and Paracetamol is shown in Fig 3. DETERMINATION OF LINEARITY: Calibration curve of absorbance Vs concentration were studied by taking concentrations ranging from 1-50μg /ml and data revealed that Beer’s Lambert law was obeyed between concentration range of 2-10μg/ml. The linearity curve for Etodolac and Paracetamol is shown in Fig 4 and Fig 5 and the statistical parameters reported on Table 1. METHOD DEVELOPMENT Simultaneous equation method: Analytical wavelengths selection was done by diluting the stock solution of Paracetamol and Etodolac at a concentration of 10 μg/ml. They were scanned in the wavelength range of 400-200nm from the overlain spectra, wavelengths 223.5 and 242.5 nm were selected for formulation of simultaneous equation for construction of calibration curves. Standard stock solution (1000 μg/ml) of Paracetamol and Etodolac were prepared separately in solvent (phosphate buffer pH 7.4) by transferring accurately weighed 100mg portion of Paracetamol and Etodolac in separate 100 ml A-class volumetric flasks and volume was made up with diluent. The solution was filtered through a 0.45μ membrane filter. The working standard solutions were prepared and further diluted with solvent to contain a Paracetamol and Etodolac over the linearity range of (2-14μg/ml).