Ivermectin is a derivative of the avermectins, a family of macrocyclic lactones produced by the filamentous bacterium Streptomyces avermitilis. With ivermectin, we found a significant inhibitory effect for concentrations 2.5 and 5 μg/mL (p<0.001), and a slight inhibitory effect for 0.15, 0.3, 0.6 and 1.25 μg/mL (p<0.01) and no inhibitory effect for 0.035 and 0.07 μg/mL (p>0.3) at 48 h incubation. The 50% IC50 of ivermectin was estimated to be 0.27 μg/mL [OD=358.38–23.35 ln(c)] after 48 h of exposure. Our in vitro results obtained with ivermectin are in agreement with the studies performed by Guzzo et al. (10).
Our results indicated that ivermectin significantly inhibited replication of the tachyzoites of T. gondii RH strain. Therefore, the present study results may be useful for further studies in combination with other drugs and animal models to develop a better treatment model for toxoplasmosis in humans."