Fluorimetric Investigation of Host-Guest Complexation of Nizatidine with beta-Cyclodextrin and its Analytical Application

The supramolecular interaction of nizatidine (NIZ) and beta-cyclodextrin (beta-CD) has been studied by spectrofluorimetry. The results showed that beta-CD reacted with NIZ to form an inclusion complex. The NIZ-beta-CD complex formed a host-guest complex in 1:1 stoichiometryand inclusion constant (K = 3.15x10(2) L mol(-1)) and was ascertained by the typical double reciprocal plots. Furthermore, the thermodynamic parameters (Delta H degrees, Delta S degrees and Delta G degrees) associated with the inclusion process were also determined. Based on the significant enhancement of the fluorescence intensity of NIZ produced through complex formation, a simple, accurate, rapid and highly sensitive spectrofluorometric method for the determination of NIZ in aqueous solution in the presence of beta-CD was developed. The measurement of relative fluorescence intensity was carried with excitation at 314 nm. The factors affecting the inclusion complex formation were studied and optimized. Under the optimum reaction conditions, linear relationships with good correlation coefficients (0.999) were in the concentration range of 0.04-0.1 mu g mL(-1) for spectrofluorimetry. The limit of detection (LOD) was found to be1.27X10(-3) mu gmL(-1). The proposed method was successfully applied to the analysis of NIZ pharmaceutical dosage formulations with good accuracy; the recovery percentages ranged from 95.4-106.85%.