DETERMINATION OF TENOXICAM IN THE PLASMA BY REVERSE PHASE HPLC METHOD USING SINGLE STEP EXTRACTION TECHNIQUE: A RELIABLE AND COST EFFECTIVE APPROACH.

A simple and cost effective RPLC-UV bio-analytical method was developed and used for tenoxicam quantification on ODS Hypersil C-18 column using classical liquid-liquid extraction technique for sample preparation. Acetonitrile was used as precipitating agent for plasma proteins and supernatant was taken for injection without any further modification. The bio-analytical method depends upon isocratic elution using binary mixture of aqueous 0.1 M potassium dihydrogen phosphate and acetonitrile in 6 : 4 ratio. The pH of mobile phase was adjusted to 2.8 which favor tenoxicam to remain undissociated throughout the analysis. The optimized flow rate of 1.0 mL/min provided proper separation of peaks and column clean up within 5 min. The UV detection was achieved at 381 nm and 4.29 min. Reproducible calibration curve gave 0.325 μg/mL LOQ, linear dynamic range from 0.325 to 20 μg/mL and recovery from plasma was 98.5% with %CV 0.2314 achieved. After validation, the method was applied in pharmacokinetic study in healthy human volunteers (n = 8). The pharmacokinetic parameters were evaluated using kinetica version 4.1.1. The values of C. and area under curve for current study were 1.776 ± 0.003 pg/mL and 179.97 ± 0.0681 (mean ± SEM) pg x h/mL. The values of t, and volume of distribution for tenoxicam in current study were 74.103 0.167 h (mean ± SEM) and 11.962 ± 0.0677 L/kg (mean ± SEM), respectively. This method was simple, sensitive and successfully applied in pharmacokinetic studies. It can be extended to bioequivalence studies and evaluation of tenoxicam in different clinical situations.