Ivermectin (22,23-dihydroavermectin B1a + 22,23-dihydroavermectin B1b) is a broad-spectrum antiparasitic drug in the avermectin family. It is sold under brand names Heartgard, Sklice, and Stromectol in the United States, Ivomec worldwide by Merial Animal Health, Mectizan in Canada by Merck, and Ivexterm in Mexico by Valeant Pharmaceuticals International. In Southeast Asian countries, it is marketed by Delta Pharma Ltd. under the trade name Scabo 6. While in development, it was assigned the code MK-933 by Merck.