Research article

Spectrophotometric determination of etodolac in pure form and pharmaceutical formulations

Ayman A Gouda¹ and Wafaa S Hassan²

¹Chemistry Department, Faculty of Science, Zagazig University, Zagazig, Egypt

²Department of analytical Chemistry, Faculty of Pharmacy, Zagazig University, Zagazig, Egypt

author email corresponding author email

Chemistry Central Journal 2008, 2:7doi:10.1186/1752-153X-2-7

Published:	14 April 2008

Abstract

Background

Etodolac (ETD) is a non-steroidal anti-inflamatory antirheumatic drug. A survey of the literature reveals that there is no method available for the determination of ETD in pure form and pharmaceutical formulations by oxidation-reduction reactions.

Results

We describe three simple, sensitive and reproducible spectrophotometric assays (A-C) for the determination of etodolac in pure form and in pharmaceutical formulations. Methods A and B are based on the oxidation of etodolac by Fe³⁺ in the presence of o-phenanthroline (o-phen) or bipyridyl (bipy). The formation of the tris-complex on reaction with Fe³⁺-o-phen and/or Fe³⁺-bipy mixtures in acetate buffer solution at optimum pH was demonstrated at 510 and 520 nm with o-phen and bipy. Method C is based on the oxidation of etodolac by Fe³⁺ in acidic medium, and the subsequent interaction of iron(II) with ferricyanide to form Prussian blue, with the product exhibiting an absorption maximum at 726 nm. The concentration ranges are 0.5–8, 1.0–10 and 2–18 μg mL^-1 respectively for methods A, B and C. For more accurate analysis, Ringbom optimum concentration ranges were calculated, in addition to molar absorptivity, Sandell sensitivity, detection and quantification limits.

Conclusion

Our methods were successfully applied to the determination of etodolac in bulk and pharmaceutical formulations without any interference from common excipients. The relative standard deviations were ≤ 0.76 %, with recoveries of 99.87 % – 100.21 %.