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Piroxicam and tenoxicam were a nonsteroidal anti-inflammatory drugs and the adverse effects associated with them had been reported. 1,2) A flow injection spectrophotometric method was described for the determination of piroxicam and tenoxicam. 3,4) Various reagents and metal chelate were used for the spectrophotometric determination of piroxicam in pharmaceutical formulations. [5][6][7] Tenoxicam and piroxicam were determined in tablets, plasma or urine samples using normal and derivative spectrophotometric techniques. [8][9][10] Piroxicam and tenoxicam were determined in human plasma, urine, serum and preparations using HPLC. [11][12][13][14] Voltammetric, polarographic, and ion selective electrode techniques were used in the determination of piroxicam and tenoxicam in pharmaceutical preparations. [15][16][17] The main objective of this study is to find a fast, accurate and sensitive spectrophotometric and potentiometric methods for the determination of piroxicam and tenoxicam in their pure and pharmaceutical preparations. The mechanism of oxidation of both drugs with iodate and N-bromosuccinimide is suggested in order to throw more light on the nature of the oxidation product formed. ExperimentalApparatus Shimadzu Model 160A UV-Visible double beam spectrophotometer with a 1.0 cm quartz cells was used.Reagents All solvents and reagents were of analytical reagent grade. Tenoxicam was provided by EIPICO where it labeled to contain 20 mg of tenoxicam per tablet or capsule. Piroxicam was provided by Pfizer where it labeled to contain 20 mg of piroxicam per tablet or capsule. Potassium iodate solution, 1% m/v; sulphuric acid for spectrophotometric assay, 30% v/v; sulphuric acid for potentiometric assay, 1 M; N-bromosuccinimide (NBS) solution, 2ϫ10 Ϫ3 M; dissolve 534 mg of NBS in 1 l of distilled water and standardized iodimetrically. 18)Reference Drug Solution Weigh accurately 50 and 100 mg of tenoxicam and piroxicam, respectively, into a 100 ml calibrated flask and dissolve in methanol up to the mark.Sample Preparation Solution Dissolve an accurately weighed amount of the tablet or capsule powder, equivalent to 50 and 100 mg of tenoxicam and piroxicam, respectively, in methanol in a 100 ml calibrated flask. Shake for 15 min, dilute to the volume and filter.Spectrophotometric Procedure Transfer different portions (containing amounts in the range 0.05-0.6 and 0.05-1.1 mg tenoxicam and piroxicam, respectively) into 50 ml stoppered conical flasks. Add 5 ml of potassium iodate solution and 3 ml of 30% v/v sulphuric acid and mix well. Add to each flask, 5 ml of cyclohexane and heat at 55°C in a water bath for 5 min for tenoxicam and piroxicam. Cool, add another 5 ml cyclohexane and transfer the cyclohexane layer quantitatively into 10 ml calibrated flasks. Measure the absorbance at 522 nm against a reagent blank.Potentiometric Procedure Transfer different portions (containing amounts in the range 0.33-3.372 and 0.33-4.08 mg tenoxicam and piroxicam, respectively) into 50 ml conical flasks. Add 3 cm 3 of sulphuric acid and...

Cyclic voltammetry and differential pulse voltammetry were used to explore the adsorption behavior of three antibacterial agents at a carbon paste electrode. The drugs were accumulated on a carbon paste electrode, and a well-defined oxidation peak was obtained in acetate buffer (pH 5.0). The adsorptive stripping response was evaluated as a function of some variables such as the scan rate, pH and accumulation time. A simple, precise, inexpensive and sensitive voltammetric method has been developed for the determination of the cited drugs (Lomefloxacin (LFX), Sparfloxacin hydrochloride (SFX), and Gatifloxacin (GFX)). A linear calibration was obtained from 2 x 10(-7) M to 4 x 10(-5) M for LFX, 2 x 10(-7) M to 6 x 10(-5) M for SFX, and GFX. The limits of detection (LOD) were 4.2 x 10(-7), 7 x 10(-7) and 6.6 x 10(-7) M, while the limits of quantification (LOQ) were 1.4 x 10(-6), 2.3 x 10(-6) and 2.2 x 10(-6) M for LFX, SFX, and GFX, respectively. The R. S. D. of five measurements at the 1 x 10(-6) M level were 0.4, 0.5 and 0.3 for LFX, SFX and GFX, respectively. The method was applied to the determination of LFX, SFX and GFX in dilute urine samples and dosage forms, and compared with the HPLC method.

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