n. any one of a group of drugs that interfere with the normal metabolic processes within cells by combining with the enzymes responsible for them. Some drugs used in the treatment of cancer, e.g. *cytarabine *fluorouracil, *methotrexate, and *mercaptopurine, are antimetabolites that prevent cell growth by interfering with enzyme reactions essential for nucleic acid synthesis. For example, fluorouracil inhibits the enzyme thymidylate synthetase. Side-effects of antimetabolites can include blood cell disorders and digestive disturbances. See also chemotherapy; cytotoxic drug.
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