Tizanidine hydrochloride is known to have several related impurities depending on the manufacturing process. There is no published ultra-performance liquid chromatography (UPLC) method which can simultaneously quantify these impurities. The current work is to design, develop, and validate an UPLC method for simultaneous estimation of all known impurities. Forced degradation studies performed on tablet formulation did not show any purity flags. To achieve sensitive and optimal separation of all the six impurities from the main moiety of Tizanidine, gradient UPLC system with ethylene bridged hybrid C8 column, 230 nm UV detection provided an optimum separation. The developed method was quick, with all six impurities eluting within 11 minutes. Low level of impurities could be quantified with limit of detection in the range 0.008%0.028% and limit of quantitation in the range 0.037%0.057%. Recoveries of all spiked impurities in Tizanidine hydrochloride were well within the range of 85%115%. Thus, the developed UPLC method is sensitive, fast, and provides precise and accurate quantitation of all known impurities in Tizanidine hydrochloride tablets. The developed method is very useful for quantitative estimation of impurities in Tizanidine hydrochloride tablets in routine quality control as well as stability monitoring programs. The method can easily be extended to quantitative cleaning residue determination in pharmaceutical industry.
Key words: Quantitative, Impurity, LOD, LOQ, Tizanidine, UPLC
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