Validation of Simultaneous Volumetric and HPLC Methods for the Determination of Pridinol Mesylate in Raw Material

Simple, sensitive, and economical simultaneous volumetric and HPLC methods for the determination of pridinol mesylate in raw material have been developed. The volumetric method is based on the reaction of pridinol with sodium lauryl sulphate in diluted sulphuric acid. Dimethyl yellow was used as indicator to detect the end point of the titration in aqueous/organic layer. The HPLC method for the determination of pridinol mesylate employs a reverse phase C18 column at ambient temperature with a mobile phase consisting of acetonitrile: 0.05？M potassium dihydrogen phosphate, pH adjusted to 5.0 (1？:？2, v/v). The flow rate was 0.8？mL/min. Quantitation was achieved with UV detection at 258？nm based on peak area. Both methods were found to be suitable for the quality control of pridinol mesylate in raw material. 1. Introduction Pridinol mesylate (Figure 1) is a CNS acting muscle relaxant used for treating muscle spasms [1]. It is administered orally and by intramuscular injection, and it has also been applied in topical preparations [1]. However, pridinol mesylate is most frequently found in associations with nonsteroidal anti-inflammatory agents, including sodium or potassium diclofenac and meloxicam. The usual dosis is 4.0？mg. Figure 1: Pridinol mesylate. A literature survey revealed some high-performance liquid chromatographic methods for the quantitation of pridinol mesylate in the presence of its relevant degradation impurities [2] or in the presence of its process-related impurities [3] in bulk drug. Both methods use a C18 column and mixtures of potassium phosphate buffer, methanol and 2-propanol as the mobile phase [2, 3]. Another analytical technique for pridinol mesylate described in the literature is based on the liquid chromatographic determination of this drug in pharmaceutical formulations with meloxicam [4]. The present paper describes a simple, rapid, precise, accurate, and economic volumetric method for the quantitation of pridinol mesylate in raw material. Results of precision and accuracy of the volumetric method were comparable with an isocratic reversed-phase HPLC method developed for the determination of pridinol mesylate in raw material. The method was validated by following the analytical performance parameters suggested by the International Conference on Harmonization (ICH) [5]. Previously we have described an HPLC method for the quantitation of Meprednisona in tablets, and we use the same lineaments [6]. 2. Materials and Methods Pridinol mesylate (99.6%) was obtained from Aldrich-Sigma (Saint Louis, MO, USA). Acetonitrile used was HPLC