β-cyclodextrin-enhanced Spectrofluorometric Methods for the Determination of Substituted Benzamides (Itopride Hydrochloride, Alizapride, and Mosapride Citrate) in Pharmaceutical Preparations

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Two spectrofluorometric methods are developed and optimized for the determination of substituted benz amides, namely itopride hydrochloride (ITO), alizapride (ALI), and mosapride citrate (MOS), in drug substances and pharmaceutical formulations. The first method is based on the measurement of the relative fluorescence intensity of the cited drugs in the absence of methyl-β-cyclodextrin at 380 ± 2 nm using an excitation wavelength of 310 nm in an aqueous solution. The linearity ranges were found to be 0.05–10, 0.1–10, and 0.1–10 μg/mL, with mean recoveries of 100.04% ± 0.21, 100.06% ± 0.65, and 100.08% ± 0.26 for ITO, ALI, and MOS, respectively. The second method is based on the significant enhancement of the fluorescence intensities of the drugs produced through complex formation with methyl-β-cyclodextrin in an aqueous solution at pH 6.6 in the case of ITO and pH 7.2 in the case of ALI and MOS. The fluorescence intensities of the formed complexes were measured at 420 ± 2 nm using an excitation wavelength of 310 nm. The linearity ranges were found to be 5–35, 3–15, and 2–30 ng/mL, with mean recoveries of 100.22 ± 30, 100.12 ± 0.24, and 100.30 ± 0.44, and limits of detection of 1.98, 1.32, and 0.66 ng/mL for ITO, ALI, and MOS, respectively. 1:1 stoichiometries for β -CD-drugs complexes were established. Association constants and Gibbs free energy were calculated by applying the Benesi–Hil de brand equation. The results were found to agree statistically with those obtained from the reference methods.