Novel methods for the visible spectrophotometric determination of diltiazem HCl and levamisole HCl in pure, tablet dosage forms and biological fluids

Author(s): Ali M.Hassan, Ahmed F.El-Asmy, Yasser B.Abd El-Raheem

Two rapid, simple, precise and sensitive extractive spectrophotometricmethods (A and B) have been developed for the determination of diltiazem hydrochloride (DT-HCl) and levamisole hydrochloride (LM-HCl) in pure, tablet dosage forms and biological fluids. Bothmethods (Aand B) involves the formation of intense yellow ion-association complex between drug(s) and either of bromocresol purple (BCP) or chlorophenol red (CPR) reagents followed by extraction with methylene chloride. The ion-associates exhibit absorptionmaxima at 399 and 402 nmfor DT-HCl and at 405 and 406 nmfor LM-HCl with BCP and CPR, respectively. The calibration curves resulting from the measurements of absorbance–concentration relations (at the optimum reaction conditions) of the extracted ion-association complexes are linear over the concentration range 2.26—27.06 and 2.26—48.48 ìg/mL for DT-HCl and 1.20—16.86 and 2.41—32.51 ìg/mL for LM-HCl with BCP and CPR, respectively. The molar absorptivities and Sandell’s sensitivities of the reaction products were calculated. In methodsAand B the slope, intercept, correlation coefficient, relative standard deviation (RSD), detection and quantitation limitswere also calculated (n=5) for DT-HCl and LM-HCl. No interference was observed fromcommon excipients present in pharmaceutical formulations. The results are well compared to those obtained by the reference methods using t- and F-tests. Therefore, the present methods are suitable for the drugs determination, as they are sensitive and precise to a high extent.

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