INTRODUCTION:

Aceclofenac is a non steroidal anti-inflammatory drug with good analgesic and anti-rheumatic properties1. Chemically it is [[[2-[(2, 6-Dichlorophenyl) amino] phenyl] acetyl] oxy] acetic acid. It is used in various pain conditions like rheumatoid arthritis, osteoarthritis and ankylosing spondylatis.^[1,2,3,4] It is official in British Pharmacopoeia.^[4]Several analytical techniques like titrimetric^[4,5], colourimetric^[7], spectroflurimetric^[7], densitometric^[8,9], HPLC^[9-11], RP–HPLC^[12,13], spectrophotometric^{[14,15,16,17]} and stripping voltametric^[18] have been reported for assay of aceclofenac. However some of these methods are costlier and time consuming. To overcome these difficulties spectrophotometric analysis serves to be the quickest, promising and reliable method for routine analytical needs. The aim of the present study is to develop a new simple, rapid, reliable and precise UV spectrophotometric method for analysis of aceclofenac from tablet formulation; method is based on measurement of UV absorbance of aceclofenac in methanol diluted with double distilled water.

MATERIALS AND METHODS:

Apparatus:

Spectral runs were made on a Shimadzu UV-Visible spectrophotometer, model- 1700 (Japan) was employed with spectral bandwidth of 1 nm and wavelength accuracy of ± 0.3 nm with automatic wavelength corrections with a pair of 10 mm quartz cells. Glasswares used in each procedure were soaked overnight in a mixture of chromic acid and sulphuric acid rinsed thoroughly with double distilled water and dried in hot air oven.

Reagents and Solution:

All the reagents used in this assay were of analytical grade and the reagent solutions were prepared using preanalysed double distilled water. Aceclofenac pure drug was obtained as a gift sample from Aristo Pharmaceuticals Limited, Mumbai. Tablets of aceclofenac were purchased from local market for analysis. Methanol diluted with double distilled water was used as a solvent for the spectrophotometric estimation.

EXPERIMENTAL:

Determination of λmax:

Weighed an accurate amount 100mg of aceclofenac was dissolved in 20ml methanol and diluted upto 100ml by double distilled water to obtain a 1000mcg/ml concentration of aceclofenac in solution. This solution was subjected to scanning between 200 – 400 nm and absorption maxima at 273nm was determined. The effect of dilution on absorption maxima was studied by diluting the above solution to 20mcg/ml and scanned from 200 – 400nm.

Standard Stock Solution:

A stock solution containing 1000mcg/ml of pure drug was prepared by dissolving accurately weighed 100mg of aceclofenac in 20ml methanol volume made upto 100ml mark by double distilled water to produce 100ml solution in a volumetric flask.

Working standard solution:

10 ml of the stock solution was further diluted to 100ml with methanol diluted with double distilled water to obtain a working standard solution containing 100mcg/mL.

Linearity and Calibration:

The aliquots working standard solution was diluted serially with sufficient methanol diluted with double distilled water to obtain the concentration range of 10 – 50 mcg/ml. A calibration curve for aceclofenac was obtained by measuring the absorbance at the λmax of 273 nm. Statistical parameters like the slope, intercept, coefficient of correlation, standard deviation, relative standard deviation, and standard error were determined.

Analysis of Marketed Tablet Formulation:

Accurately weighed the 20 tablets and powdered. The powder equivalent to 100mg of aceclofenac was transferred to 100ml volumetric flask and 20ml methanol is added to dissolve the aceclofenac in it and made the volume to mark with double distilled water. This mixture was sonicated for 15 minutes and filtered through Whatmann filter paper No. 41. Aliquots (1ml, 2ml, 3ml, 4ml, 5ml) of the sample were removed and diluted to 10 ml with methanol diluted with double distilled water to obtain strengths as 10mcg/ml, 20mcg/ml, 30mcg/ml, 40mcg/ml and 50mcg/ml and determined the respective absorbance at 273nm against the methanol diluted with double distilled water as blank. Two different formulations of different manufacturers were used for study.

Recovery studies:

Recovery studies were performed to judge the accuracy of the method. 1ml of standard formulation (100mcg/ml) was taken in three 10ml volumetric flask and to it 80%, 100% and 120% (i.e. 0.8ml, 1.0ml, 1.2ml) of working standard solution (100mcg/ml) added respectively and made the volume upto the mark. The respective absorbance at 273nm was recorded against the blank. The amount of added concentration was determined from the obtained absorbance values and percent recovery was determined for each formulation.

Robustness:

The evaluation of robustness was performed for system suitability to ensure the validity of analytical procedure. This was done by varying the instrument, analyst, and time of study. The analysis was performed on Shimadzu UV-Visible spectrophotometer, model- 1700 (Japan) and UV-Visible Spectrophotometer model -1800 (Japan). Interday and intraday analysis was performed by changing the analyst.

Fig. 1: UV Scan of Aceclofenac in methanol diluted with double distilled water

Fig. 2: Calibration curve of Aceclofenac in methanol diluted with double distilled water

Table No. I: Optical characteristics and precision

Parameter	Observations
Absorption maxima	273 nm
Beer's law limit	2 – 20 mcg/ml
Coefficient of Correlation	0.999894
Regression equation	Y = 0.02502 X + 0.0053
Slope	0.02502
y intercept	0.0053
Molar absorptivity (lit/mole/cm)	8861.833057
Sandell's sensitivity (mcg/Sq.cm/0.001)	0.039968

RESULTS:

The UV scan of standard solution between 200 – 400 nm showed the absorption maxima at 273nm, shown in fig. 1. The Beer’s law was verified from the calibration curve by plotting a graph of concentration vs absorbance. The plot is shown in fig. 2. Regression analysis showed very good correlation. The calibration plot revealed zero intercept which is clear by the regression analysis equation Y = mX + C. (Where Y is absorbance, m is the slope and X is the concentration of aceclofenac in mcg/ml) as obtained by the least square method..

The results thus obtained are depicted in Table No.I. The results of analysis for assay and recovery studies for two different formulations were studied and are shown in Table No. II. No significant variations were observed on interday and intraday analysis. Also no significant variations were observed on changing the instrument make and model.

DISCUSSION:

The spectrum of aceclofenac in methanol diluted with double distilled water showed the absorption maxima at 273 nm. No effect of dilution was observed on the maxima, which confirmed the maxima at 273nm. The statistical analysis of data obtained for the calibration curve of aceclofenac in pure solution indicated a high level of precision for the proposed method, as evidenced by low value of coefficient of variation. The coefficient of correlation was highly significant. The linearity range was observed between 2 – 20 mcg/ml. The plot clearly showed a straight line passing through origin (Y = 0.02502 X + 0.0053). The estimated method was validated by low values of % RSD and standard error, indicating accuracy and precision of the methods. Excellent recovery studies further proves the accuracy of the method. Robustness of the method was studied by varying the instrument, time of study and analyst. Reproducibility of the results confirmed the robustness of the method.

CONCLUSION:

From the results and discussion the method described in this paper for the determination of aceclofenac from tablet formulation is simple, accurate, sensitive reproducible and economical. The proposed method utilizes inexpensive solvents. The proposed method could be applied for routine analysis in quality control laboratories.

ACKNOWLEDGEMENTS:

Authors are grateful to Aristo Pharmaceuticals Limited, Mumbai for providing the gift sample of Aceclofenac. We are also thankful to the Principal and Head of Pharmaceutical Chemistry Department of Government College of Pharmacy, Karad for providing the necessary facilities to carry out this work.

REFERENCES:

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Received on 15.09.2009 Modified on 07.11.2009

Asian J. Research Chem. 3(1): Jan.-Mar. 2010 page 87-89

Formulation	Label Claim	% Label Claim found	Standard Deviation	Coefficient of Variation	Standard error	% Recovery
Tablet I	100mg	100.12%	0.006834	0.02529	0.003056	99.38%
Tablet II	100mg	99.91%	0.006427	0.02858	0.002874	100.12%