<b>Indirect spectrophotometric determination of piroxicam and tenoxicam through oxidation with potassium permanganate</b>

Abstract

Three rapid, simple, accurate and selective validated spectrophtometric methods (A, B and C) for the determination of piroxicam (PX) and tenoxicam (TX) in bulk sample and in dosage forms are described. The methods are based on the oxidation of the studied drugs by a known excess of potassium permanganate in sulfuric acid medium and subsequent determination of unreacted oxidant by reacting it with Methylene Blue (Basic Blue 9) dye (method A), Acid Red 27 (Amaranth) dye (method B) and Acid Orange 7 (orange II) dye (method C), in the same medium at a suitable λmax = 660, 520 and 485 nm, respectively. The reacted oxidant was found to be corresponding to the drug content. Regression analysis of Beer-Lambert plots showed good correlations in the concentration ranges 1.0-8.0, 1.0-9.0 and 1.0-7.2 µg mL-1 using methods A, B and C, respectively, for PX and 0.3-7.0, 0.3-1.6 and 0.3-2.5 µg mL-1 using methods A, B and C, respectively, for TX. The stoichiometric ratios for the cited drugs to oxidant were studied. The optimum reaction conditions and other analytical parameters were evaluated. The proposed methods were applied successfully to determine the examined drugs either in pure form or pharmaceutical formulations with good accuracy and precision. The relative standard deviations were ≤ 0.33 with recoveries 98.9-101.7% for PX and ≤ 0.49 with recoveries 99.4-102.0% for TX.

Sensitive Voltammetric Method for Piroxicam Determination in Pharmaceutical, Urine and Tap Water Samples Using an Anodically Pretreated Boron-Doped Diamond Electrode

“…Several analytical methods for assaying PRX in pharmaceutical formulations and human body fluids have been described in the literature [6][7][8][9][10][11][12][13][14]. Most of these methods use chromatographic and spectrophotometric techniques in which, commonly, organic toxic solvents are used, generating high amounts of waste, the analytical frequency is low and requires prior separation steps and the analytical process is tedious.…”