Determination and in-process control of zolpidem synthesis by high-performance liquid chromatography

A rapid HPLC method for determination of zolpidem and its degradation product in tablets using a monolithic column

A simple, accurate reverse phase high-performance liquid chromatographic method, utilizing a monolithic silica column, for determination of zolpidem hemitartrate and its degradation product in tablet dosage form was developed. Analysis was achieved on the monolithic, C18 (100 mm, 3.9 mm) column, in isocratic mode with acetonitrile-NaH2PO4 (pH 7.0; 0.01 M; 35:65, v/v) as mobile phase and a flow rate of 2.5 mL/min at room temperature with UV detection at 245 nm. Diazepam was applied as an internal standard. The retention time of zolpidem and its degradation product was 2.14 and 1.89, respectively. Calibration curve was linear in the range of 0.12-5 µg/mL and the recovery values were found to be 97-101%. The limit of quantitation was determined 0.12 μg/mL. The relative standard deviation values of intraday and interday studies were calculated as 0.13-1.1% and 0.54-1.3%, respectively.

Development and Validation of a Reversed-Phase HPLC Method for the Estimation of Zolpidem in Bulk Drug and Tablets

In the present study an isocratic reversed-phase high-performance liquid chromatography method was developed for the estimation of zolpidem in bulk drug and pharmaceutical dosage forms. The quantification was carried out on C18columns. A mixture of acetonitrile-ammonium acetate (pH=8.0, 0.02 M) (60 : 40 v/v) was used as the mobile phase, at flow rate of 1.0 mL/min and the determination wavelength at 245 nm. The retention time of zolpidem was found to be 3–5 min. The validation of the proposed method was carried out for specificity, linearity, accuracy, precision, limit of detection, limit of quantification, and robustness. The linear dynamic range was from 2.5 to 30 μg mL−1. Regression equation was found to bey=0.1416x+0.0183with correlation coefficientr=0.9996. The percentage recovery obtained for zolpidem was greater than 96.5%. Limit of quantification and limit of detection were found to be 2.5 μg mL−1and 0.83 μg mL−1, respectively. The developed method can be used for routine quality control analysis of zolpidem in tablet formulations.

Spectrophotometric methods for determination of zolpidem tartrate in tablet formulation

AIM

The study aims to develop simple, sensitive, rapid, accurate and precise spectrophotometric method for estimation of Zolpidem tartrate in tablet dosage forms.

MATERIALS AND METHODS

For method I, II, III and IV in a series of 10 ml volumetric flask, aliquots of standard drug solution (100 µg/ml) in 0.1N HCl were transferred and diluted with same so as to give several dilutions in concentration range of 5-30 µg/ml, 5-30 µg/ml, 10-50 µg/ml and 5-40 µg/ml respectively of zolpidem tartrate. To 5 ml of each dilution taken in a separating funnel, (5 ml of bromo phenol red, bromo cresol purple, bromo cresol green and bromo phenol blue for method I, II, III and IV respectively) reagent and 5 ml of chloroform was added. Reaction mixture was shaken gently for 5 min and allowed to stand so as to separate aqueous and chloroform layer. Absorbance maxima measured at 407 nm, 417 nm, 412 nm and 415 nm for method I, II, III and IV respectively.

RESULTS

The recovery studies were found close to 100 % that indicates accuracy and precision of the proposed methods. The statistical analysis was carried out and results of which were found satisfactory. Standard deviation values were found low that indicated reproducibility of the proposed methods.

CONCLUSION

Based on results the developed methods could be used for routine estimation of zolpidem tartrate from tablet formulations.