SPECTROPHOTOMETRIC METHODS FOR SIMULTANEOUS ESTIMATION OF MELATONIN AND ZOLPIDEM FROM THE COMBINED TABLET DOSAGE FORM

The present work aimed to develop and validate spectrophotometric methods for simultaneous estimation of melatonin and zolpidem in combined dosage form. Method is based on solving a simultaneous equation. Absorbance of melatonin and zolpidem were measured at the respective absorbance maximum (lambda (max)) at 277 and 311 nm. Methods are validated according to ICH guidelines. Linearity range for melatonin and zolpidem is 3-10.5 mu g/ml and 5-17.5 mu g/ml at respective selected wavelengths. The coefficient of correlation for melatonin at 277 nm and zolpidem at 311nm is 0.9940 and 0.9969, respectively. A percentage estimation of melatonin and zolpidem from the tablet dosage form is101.80 % and 101.70 % respectively, with standard deviation less than 2. The proposed method was simple, rapid, and validated and can be used successfully for the routine simultaneous estimation of melatonin and zolpidem combined tablet dosage form.