Stability Indicating Methods for Determination of Nalbuphine- Hydrochloride

Three simple, sensitive and reproducible spectrometric methods for the selective determination of nalbuphine–HCl in presence of its oxidative degradate were investigated. The first method depended on the quantitative densitometric evaluation of thin layer chromatograms of the drug at 284 nm using chloroform–methanol–acetic acid (7:3:0.05 v/v/v) as a mobile phase, in a concentration range of 10-30 µg/spot. The second one used the pH induced difference absorbance (∆A) between 0.1M NaOH and 0.1 M HCl drug solutions at 299 nm to determine 20-160 µg mL-1 of the drug. The third method was a bivariate calibration algorithm for the determination of nalbuphine–HCl over concentration range of 20-200 µg mL-1. The proposed methods selectively analysed the drug in presence of up to 80% of its oxidative degradate with mean recoveries of 100.63±1.03 for densitometric method and up to 90% with recoveries of 99.97±1.16 and 100.09±1.47% regarding the two other methods, respectively. The three proposed methods were successfully applied to analyse nalbuphine– HCl in its preparations, the results obtained were statistically analysed and found to be in accordance with those given by the compendial method.