Nitazox 500mg Tablets NITAZOX 500 MG contains Nitazoxanide, a synthetic broad-spectrum antiprotozoal and antiviral agent belonging to the thiazolide class. Nitazoxanide acts by inhibiting pyruvate:ferredoxin oxidoreductase (PFOR) enzyme-dependent electron transfer reactions essential for anaerobic energy metabolism in protozoa and anaerobic bacteria. NITAZOX 500 MG is indicated for the treatment of diarrhea caused by Cryptosporidium parvum and Giardia lamblia, as well as other protozoal infections and intestinal helminthiasis.