Spectrophotometric Determination Of H₂ Receptor Antagonist Based On Charge-Transfer Reactions

Objective:A rapid,simple and sensitive spectrophotometric methods for the quantitative analysis of cimetidine,nizatidine and ranitidine hydrochloride in pharmaceutical formulations have been established.Methods:The charge transfer reaction between cimetidine,nizatidine and ranitidine hydrochloride as electron donors and an appropriate electron acceptor has been studied by spectrophotometric method;the optimum reaction conditions have been optimized and established.The complex ration between cimetidine,nizatidine,ranitidine hydrochloride and electron acceptor was determined by the molar continuous change method and the molar ratio method.Results:?1?Optimal reaction condition of charge transfer reaction between cimetid-ine and DDQ:Polyoxyethylene castor oil EL-40 had a sensitizing effect on the absorption of cimetidine and DDQ,cimetidine and DDQ were placed in acetonitrile for10 min at room temperature,and the absorbance was measured at 456 nm.Lambert-Beer law was obeyed over the concentration range of 10.00⁶0.00?g·m L^-1,the correlation coefficient was 0.9992.The limit of detection and quantity were 2.07?g·mL^-1 and 6.28?g·m L^-1 respectively.The precision of the methods was satisfactory;the RSD of repeatability and inter-day precision were 0.90%and 0.94%respectively.The determination of cimetidine content in tablets and capsules by the proposed method showed no significant difference with the pharmacopoeia.The recoveries were98.98%¹01.63%and 98.00%¹01.60%.The molar ratio of cimetidine and DDQ was1:1.?2?Optimal reaction condition of charge transfer reaction between nizatidine and PCA:nizatidine and PCA were placed in acetonitrile for 10 min at room temperature,and the absorbance was measured at 518 nm.Lambert-Beer law was obeyed over the concentration range of 32.00²00.00?g·m L^-1,the correlation coefficient was 0.9997.The limit of detection and quantity were 3.22?g·m L^-1 and 9.77?g·m L^-1 respectively.The precision of the methods was satisfactory;the RSD of repeatability and inter-day precision were 0.75%and 1.22%respectively.The determination of nizatidine content in tablets and capsules by the proposed method showed no significant difference with the literature method.The recoveries were 98.13%¹00.62%and 98.67%¹00.21%.The molar ratio of nizatidine and PCA was 1:1.?3?Optimal reaction condition of charge transfer reaction between ranitidine hydroch-loride and PCA:ranitidine hydrochloride and PCA were placed in acetonitrile for 10min at room temperature,and the absorbance was measured at 519 nm.Lambert-Beer law was obeyed over the concentration range of 40.00²00.00?g·m L^-1,the correlation coefficient was 0.9998.The limit of detection and quantity were 10.16?g·mL^-1 and30.80?g·m L^-1 respectively.The precision of the methods was satisfactory;the RSD of repeatability and inter-day precision were 0.40%and 0.56%respectively.The determination of ranitidine hydrochloride content in capsules by the proposed method showed no significant difference with the pharmacopoeia.The recoveries were98.73%¹01.83.The molar ratio of ranitidine hydrochloride and PCA was 1:1.Conclusion:The proposed spectrophotometric methods have the advantages of simplicity,accuracy and convenience for the quantitation of cimetidine,nizatidine and ranitidine hydrochloride.Hence,the proposed methods can be used for the quality control of the cited drugs and can be extended for routine analysis of the drugs in bulk and ddosage forms.