In Vitro Effects of Ivermectin and Sulphadiazine on Toxoplasma gondii.

OBJECTIVE Ivermectin and sulphadiazine were tested individually to determine their in vitro effects on Toxoplasma gondii grown in human epidermoid larynx carcinoma (Hep-2) cell culture. STUDY DESIGN In-vitro study. MATERIAL AND METHODS Toxoplasma growth was quantities by an enzyme immunoassay performed directly on the fixed cultures, using a rabbit anti-T. gondii immunoglobulin G as the first antibody and a phosphatase-labeled anti-rabbit immunoglobulin G as the second antibody. For each drug, regression models were used to quantify the relationship between optical density values and antimicrobial agent concentrations in the cultures. RESULTS The 50% inhibitory concentrations (IC50) of ivermectin and sulphadiazine were found to be 0.2 μg/mL and 7.3 μg/mL after 48 h of exposure, respectively. None of the concentrations tested for each drugs demonstrated toxicity to Hep-2 cells after 72 h of incubation. CONCLUSION These results indicate that ivermectin significantly inhibited replication of the tachyzoites of T. gondii RH strain.