Effects of Incremental Doses of Chloroquine Phosphate on the Formed Elements of Blood.

Easy access to chloroquine (CQ) in many developing countries can result to intake of inappropriate doses. This study was therefore conducted to evaluate the acute effects of high doses of CQ on hematological parameters and plasma Na+and K+ concentrations. To do this, Swiss albino rats were administered incremental doses of CQ intraperitoneally at dose rates ranging between 0.5 to 8mg/kg b.wt. Two hours later, blood samples were taken and analysed. 8mg/kg b.wt of CQ induced significant decrease in red blood cells (RBC), hemoglobin (Hb) and significant increase in mean corpuscular volume (MCV). There was a significant increase in white blood cell count at all dose levels. Packed cell volume (PCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) were not affected by all dose ranges. There was significant increase in plasma Na+ and K+ by dose rates of 4 and 8 mg/kg but not by lower doses. These data indicate that most CQ induced toxicities on the formed elements of blood occurs at doses greater than 4 times the standard therapeutic dose in rats. k ey words: chloroquine, toxicity, blood, rats