| cholinergic parasympathomimetic agent | <pharmacology> A chemical substance that causes the release of choline (acetylcholine) from parasympathetic nerve endings. (15 Jan 1998) |
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| cholinergic receptors | Chemical sites in effector cells or at synapses through which acetylcholine exerts its action. (05 Mar 2000) |
| cholinergic system | <physiology> The system of nerve cells that uses acetylcholine as its neurotransmitter, nerve cells in the cholinergic system are damaged in the brains of Alzheimer patients. (15 Jan 1998) |
| cholinergic urticaria | A form of physical or non-allergic urticaria initiated by heat (e.g., hot baths, physical exercise, pyrexia, exposure to sun or to a warm room) or by excitement; the rather distinctive lesions consist of pruritic areas 1 to 2 mm in diameter surrounded by bright red macules. Synonym: heat urticaria. (05 Mar 2000) |
| mixed opioid agonist-antagonist | <pharmacology> A compound that has an affinity for two or more types of opioid receptors and blocks opioid effects on one receptor type while producing opioid effects on a second receptor type. (13 Nov 1997) |
| competitive antagonist | An antimetabolite. (05 Mar 2000) |
| muscarinic antagonist | Drugs which bind with muscarinic cholinergic receptors but do not activate them, thus preventing access to acetylcholine; examples include atropine, scopolamine, propantheline, and pirenzepine. (05 Mar 2000) |
| H2 antagonist | <pharmacology> A class of anti-ulcer medication which work through the inhibition of basal and nocturnal gastric acid secretion by competitive inhibition of the action of histamine at histamine H2 receptor sites on the parietal cells. Drugs of this type block gastric acid secretion and are therefore clinically useful in treating duodenal ulcers. Examples include cimetidine (Tagamet), famotidine (Pepcid), nizatidine (Axid) and ranitidine (Zantac). (27 Sep 1997) |
| nicotinic cholinergic receptor | A class of receptors responsive to acetylcholine that also are activated by nicotine; ganglionic (including the adrenal medulla) and neuromuscular receptors. Two classes exist: nicotinic-neuronal and nicotinic-muscular. (05 Mar 2000) |
| insulin antagonist | Something that opposes or fights the action of insulin. Insulin lowers the level of glucose (sugar) in the blood, whereas glucagon raises it, therefore, glucagon is an antagonist of insulin. (09 Oct 1997) |
| oestrogen antagonist | <pharmacology> A drug or compound which inhibit or antagonise the action or biosynthesis of oestrogen. Tamoxifen also has agonist or stimulatory actions as well as blocking effects. There are also selective oestrogen-receptor modulators (SERMs). For example, raloxifene (trade name Evista) is classified as a SERM because it prevents bone loss (like oestrogen) and lowers serum cholesterol (like oestrogen) but (unlike oestrogen) does not stimulate the endometrial lining of the uterus. (12 May 2002) |
| enzyme antagonist | An antimetabolite or inhibitor of enzyme action. (05 Mar 2000) |
| folate antagonist | <pharmacology> One of a group of substances which blocks the formation of nucleotides that require the presence of folate (one of the B vitamins) before they can be made. The substance does this by blocking key steps in the reaction sequence. These substances are often used to treat cancer because fast-growing cancerous cells usually need to use the blocked reactions more than normal cells. (09 Oct 1997) |
| folic acid antagonist | <pharmacology> A chemical which inhibits a cells capacity to use folic acid and so prevent cell division, for example methotrexate. See: chemotherapy. (12 Nov 1997) |