TERFENADINE DETERMINATION USING DIFFERENT ANALYTICAL METHODS

Different methods for terfenadine determination were investigated. Non-aqueous titration and TLC techniques were used to assay the starting material. TLC method was found to be more selective in differentiating between batches of different purity. The drug solution in a mixture of methanol, acetic acid and water exhibited two maxima at 238 and 260 nm. The pharmaceutical dosage forms were assayed by the formation of an ion pair complex with methyl orange, which was extracted in dichloromethane and showed a maximum at 425 nm. The colour obtained was stable and the complex obeyed the Beer Lambert law between 0.004-0.016 mg/ml. The optimum pH of the aqueous layer was from 3.5-6.0. This method was applied for tablets, capsules, suspension and content uniformity assays and was found to be simple and reproducible.