Heavy metals are widely distributed in the environment and accumulate in select tissues of the human body after exposure. Metal ions form chelate complexes with certain drug molecules which may result in therapeutic consequence. In this study, the in vitro availability of ciprofloxacin alone and then in the presence of cadmium (Cd), chromium (Cr), manganese (Mn) and zinc (Zn) at concentrations reported in human blood in Zaria, Nigeria, was evaluated. The interactions were carried out in simulated blood pH (phosphate buffer pH 9) at 37oC over a period of 180 minutes. A double scanning UV/VIS spectrophotometer (Helios Zeta, Model 164617) was used to analyze the drug content by measuring absorbance at 271.4 nm. The availability of ciprofloxacin alone reached a maximum of 105.3 % after 105 minutes. Afterwards, it gradually declined to 90.4 % by 180 minutes. Free ciprofloxacin observed in the presence of Cd, Cr and Zn was 92.9, 84.0 and 76.0 % respectively after 180 minutes, revealing significant decreases (P < 0.001) in the availability of the drug. However, the availability of ciprofloxacin was not significantly (P < 0.05) affected in the presence of Mn, with the drug achieving an availability of 96 % after 180 minutes. The results indicate that the availability of ciprofloxacin may be reduced in the presence of Cd, Cr and Zn which can result in unpredictable therapeutic outcomes.
Key words: Ciprofloxacin, in vitro availability, cadmium, chromium, manganese, zinc