Effects of Cadmium, Lead, Manganese, and Zinc at WHO Safe Limits in Drinking Water on the <i>in Vitro</i> Availability of Chloramphenicol

Abstract

In the present study, The in vitro availability of chloramphenicol was studied in the presence of lead (Pb), cadmium (Cd), manganese (Mn) and zinc (Zn) at 0.01, 0.003, 0.5 and 3 mg/L respectively corresponding to WHO safe limits in drinking water for each of the metals. The in vitro availability study was carried out in simulated gastric juice (0.1 M HCl) and intestinal pH (phosphate buffer pH 9.0) at 37°C using a dissolution apparatus. Samples were taken at 15 minutes intervals over a period of 3 hours and analyzed for concentration of chloramphenicol available using a Helios Zeta Model 164617 UV/VIS spectrophotometer at 278nm. In simulated gastric juice, a maximum availability of 99.48 % was achieved for chloramphenicol alone, while 89.48, 93.48, 105.88 and 93.60% of the drug was detected in the presence of Cd, Mn, Pb, and Zn respectively. The corresponding maximum availabilities in simulated intestinal pH were 64.12 for chloramphenicol alone, and 64.36, 83.76, 80.72 and 64.96 % in the presence of Cd, Mn, Pb, and Zn respectively. The presence of Cd did not affect the overall availability of chloramphenicol in both media; while the availability of the drug was observed to increase slightly in the presence of Pb in both media. In simulated gastric juice, Mn and Zn did not affect the availability of chloramphenicol. However, their presence slightly increased the availability of the drug in simulated intestinal pH. The results of this study indicate that the absorption and subsequent bioavailability of chloramphenicol may not be reduced by Cd, Pb, Mn, and Zn at concentrations corresponding to WHO safe limits in drinking water. Bioavailability may even be enhanced especially in the intestine, which may result in therapeutic effectiveness. Key words: Chloramphenicol, metal cations, in vitro availability