Simultaneous Estimation of Tizanidine and Valdecoxib in Combined Dosage Forms by RP-HPLC Method

Abstract

A simple, selective, rapid, precise and economical reverse phase HPLC method has been developed for the simultaneous estimation of tizanidine and valdecoxib from tablets. The process was carried out on a Phenomenex LUNA C₁₈(25 cm x 4.6 mm i.d. 5 μ) column with a mobile phase consisting of acetonitrile : 0.5% triethylamine (adjusted to pH 3.0 using orthophosphoric acid) (50 : 50 v/v) at a flow rate of 1.0 mL/min. Detection was carried out at 240 nm. nimesulide was used as internal standard. The retention time of nimesulide, valdecoxib and tizanidine was 6.04, 8.95 and 10.34 min respectively. The validation of the proposed method was also carried out. The proposed method can be used for the estimation of these drugs in combined dosage forms.