folic acid antagonist

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antagonistic muscle. (see illustration.)
1. a substance that tends to nullify the action of another, as a drug that binds to a cellular receptor for a hormone, neurotransmitter, or another drug blocking the action of that substance without producing any physiologic effect itself. See also blocking agent.
2. a tooth in one jaw that articulates with one in the other jaw.
α-adrenergic antagonist alpha-adrenergic blocking agent.
β-adrenergic antagonist beta-adrenergic blocking agent.
folic acid antagonist see folic acid antagonist.
H1 receptor antagonist any of a large number of agents that block the action of histamine by competitive binding to the H1 receptor. Such agents also have sedative, anticholinergic, and antiemetic effects, the exact effect varying from drug to drug, and are used for the relief of allergic symptoms and as antiemetics, antivertigo agents, sedatives, and antidyskinetics in parkinsonism. This group is traditionally called the antihistamines.
H2 receptor antagonist an agent that blocks the action of histamine by competitive binding to the H2 receptor; used to inhibit gastric secretion in the treatment of peptic ulcer.

folic acid

a vitamin of the B complex; it is involved in the synthesis of amino acids and DNA. Green vegetables, liver, and yeast are major food sources; folic acid can also be produced synthetically. Folic acid deficiency (leading to megaloblastic anemia) may result from the inability of the body to use the vitamin. Because of the important role of folate in prevention of neural tube defects, it is now recommended that 400 μg of folate be taken daily before conception occurs. See also vitamin.
folic acid antagonist an antimetabolite of folic acid; some are used as antineoplastic agents because they interfere with DNA replication and cell division by inhibiting the enzyme dihydrofolate reductase. Examples include trimethoprim, an antibacterial; pyrimethamine, an antimalarial agent; and methotrexate, an antineoplastic agent.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

fo·lic ac·id an·tag·o·nist

(fō'lik as'id an-tag'ŏ-nist)
Modified pterins, such as aminopterin and amethopterin, which interfere with the action of folic acid and thus produce the symptoms of folic acid deficiency; used in cancer chemotherapy.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
References in periodicals archive ?
(3) Women who have a history of medical complications, including renal disease with altered renal function, epilepsy, cancer, or use of folic acid antagonists such as valproic acid.
Methods: We assessed exposure to folic acid antagonists that act as dihydrofolate reductase inhibitors and to certain antiepileptic drugs in 3,870 infants with cardiovascular defects, 1,962 infants with oral clefts, and 1,100 infants with urinary tract defects, and also in 8,387 control infants with malformations, the risk of which is not reduced after vitamin supplementation.
It is also indicated to reduce toxicity and counteract the effects of impaired methotrexate elimination and of inadvertent overdosage of folic acid antagonists.
"Most of the women in our registry were taking AEDs that are folic acid antagonists," Maya Nambisan, study coordinator of the registry, said.