In Vitro Simulation of Drug Interaction: Ciprofloxacin/Zinc Chloride

In vitro dissolution testing has long been used as a tool in drug product development and quality control, however, its potential for drug/food and drug/drug interactions has not yet been fully exploited. Ciprofloxacin absorption in vivo may be reduced when co-administered with different metallic compounds. In the present study, in vitro ciprofloxacin solubility and drug dissolution from tablets were performed in the reactive media containing zinc chloride in order to simulate ciprofloxacin/zinc interaction observed in vivo. The precipitates collected from dissolution vessel and from mixture containing ciprofloxacin-hydrochloride and zinc-chloride were investigated using XRPD, TGA, DCS, FTIR. Ciprofloxacin-hy-drochloride solubility and drug dissolution from tablet were reduced in aqueous media containing increasing amounts of zinc-chloride. Complex with probable chemical structure [cfH 2 ] 2  · [ZnCl 4 ] · 2H 2 O was generated in the presence of high concentrations of ciprofloxacin-hydrochloride and zinc-chloride, indicating that small volume dissolution experiments can be useful in biopharmaceutical characterisation of drug interaction studies.