SIMULTANEOUS ESTIMATION OF ZOLPIDEM TARTRATE AND MELATONIN IN TABLET DOSAGE FORM BY UV SPECTROPHOTOMETRY AND RP-HPLC
Keerthisikha Palur*, Sreenivasa Charan Archakam, Hemavathi Bodagala, Sridhar Chenchugari and Ranganayakulu Diviti
ABSTRACT
Zolpidem Tartrate and Melatonin combination is used in the treatment of insomnia characterized by difficulties with sleep onset and/or sleep maintenance. Three analytical methods were proposed for the quantitative Estimation of Zolpidem Tartrate and Melatonin in Tablet dosage form, among which two methods were based on UV Spectrophotometric principles and the other is based on RP-HPLC. Method-1 is based on First order derivative zero crossing UV-spectrophotometry. The first derivative spectrum of zolpidem tartrate crosses at 254.65 nm and that for Melatonin crosses at 336.34 nm. The assay values for this method was found to be 90 %(w/w) and 103 %(w/w) for Zolpidem tartrate and Melatonin respectively. Method-2 is based on Absorbance Ratio method in which the absorbance values were measured at 243 nm (λmax for zolpidem tartrate), and 301.50 nm (isobestic point). The assay values for this method were found to be 108% (w/w) and 103%(w/w) for Zolpidem tartrate and Melatonin respectively. For both the methods, precision and accuracy values were within the limits. HPLC was carried out by reversed-phase mode on a C18 column with a mobile phase composed of mixed phosphate buffer (pH 4.5) and acetonitrile in the proportion of 55:45 v/v, at a flow rate of 1.0 mL/min with UV detection at 264 nm. The method was found to be specific, precise and accurate with the mean recovery of 90.08% for Zolpidem tartrate and 100.43%.Assay content of Zolpidem tartrate and melatonin was determined and the mean assay was found to be 104.23%(w/w) and 105.57%(w/w). Forced degradation studies were carried out for Zolpidem tartrate and Melatonin in acidic and alkaline, Oxidative and Thermal conditions.
Keywords: Zolpidem tartrate, Melatonin, UV-Spectrophotometry, RP-HPLC, First order derivative zero crossing method, Absorbance Ratio method.
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