The drug methotrexate (right) is an<unk>  that interferes with the metabolism of folic acid (left). An<unk>  is a chemical that inhibits the use of a metabolite, which is another chemical that is part of normal metabolism. Such substances are often similar in structure to the metabolite that they interfere with, such as the antifolates that interfere with the use of folic acid; thus, competitive inhibition can occur, and the presence of<unk> s can have toxic effects on cells, such as halting cell growth and cell division, so these compounds are used as chemotherapy for cancer.
Antimetabolite
Toxicophore
Topoisomerase inhibitor
Immunoconjugate
Monoclonal antibody
Antioxidant
Antiparasitic
Antiviral drug