Abstract: Purpose: The mechanics of ion-pair complex formation between 1-cyclopropyl- 6-fluoro- 4-oxo- 7-piperazin- 1-yl- quinoline- 3-carboxylic acid monohydrochloride (CPF) and 4,4'-(1,1-dioxido-3H-2,1-benzoxathiole-3,3-diyl)bis(2,6-dibromophenol) (BPB) and its application in Ghana for quality control of some medicinal agents have been examined. Method: CPF was allowed to react with BPB in aqueous acetate buffer of pH 2.8 at room temperature (29±10C), extracting the ion-pair complex into CHCl3 and determining the absorbance at 420nm. The optical characteristics, conditional stability constant and free energy of formation of the complex were also evaluated, finally applying the method to the assay of six brands of CPF tablets. Results: Effective linear dynamic range according to the Ringbom’s plot was 5.0–27.5 µgmL-1. Molar absorptivity, Sandell’s sensitivity index and degree of dissociation of the complex were 1.06x104 Lmol-1cm-1, 0.036 µgcm-2 and 0.163 respectively. The logarithmic conditional stability constants and Gibb’s function determined by the continuous variations and mole ratio methods were respectively 5.95±0.110;-34,401.00Jmol-1 and 5.76±0.214;-33,326.83Jmol-1. Conclusion: The CPF tablets were successfully assayed and the method showed a great deal of precision and accuracy making its application suitable for regular quality monitoring of CPF and its congeners in Ghana.
 

Keywords: Ion-pair, ciprofloxacin, bromophenol blue, drug quality, counterfeit, fluoroquinolone