| antipsychotic agent | A functional category of neuroleptic drugs that are helpful in the treatment of psychosis and have a capacity to ameliorate thought disorders (e.g., chlorpromazine, haloperidol). See: neuroleptic. Synonym: antipsychotic, major tranquilliser. (05 Mar 2000) |
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| typical achromatopsia | Achromatopsia with absent colour vision, nystagmus, reduced visual acuity, and light aversion. Synonym: rod monochromatism, typical achromatopsia. (05 Mar 2000) |
| typical pseudocholinesterase | A cholinesterase formed in the liver and present in plasma; it catalyses the hydrolysis of succinylcholine, first into succinylmonocholine and choline, and then into choline and succinic acid. (05 Mar 2000) |
| antipsychotic | <pharmacology> A drug that is effective in the treatment of psychosis. Antipsychotic drugs (also called neuroleptic drugs and major tranquillisers) are a chemically diverse (including phenothiazines, thioxanthenes, butyrophenones, dibenzoxazepines, dibenzodiazepines and diphenylbutylpiperidines) but pharmacologically similar class of drugs used to treat schizophrenic, paranoid, schizoaffective and other psychotic disorders, acute delirium and dementia and manic episodes (during induction of lithium therapy), to control the movement disorders associated with Huntington disease, Gilles de la Tourette's syndrome and ballismus and to treat intractable hiccups and severe nausea and vomiting. Antipsychotic agents bind to dopamine, histamine, muscarinic cholinergic, a adrenergic and serotonin receptors. Blockade of dopaminergic transmission in various areas is thought to be responsible for their major effects: antipsychotic action by blockade in the mesolimbic and mesocortical areas, extrapyramidal side effects (dystonia, akathisia, parkinsonism and tardive dyskinesia) by blockade in the basal ganglia and antiemetic effects by blockade in the chemoreceptor trigger zone of the medulla. Sedation and autonomic side effects (orthostatic hypotension, blurred vision, dry mouth, nasal congestion and constipation) are caused by blockade of histamine, cholinergic and adrenergic receptors. (13 Nov 1997) |
| antipsychotic agents | Agents that control agitated psychotic behaviour, alleviate acute psychotic states, reduce psychotic symptoms, and exert a quieting effect. They are used in schizophrenia, senile dementia, transient psychosis following surgery or myocardial infarction, etc. These drugs are often referred to as neuroleptics alluding to the tendency to produce neurological side effects, but not all antipsychotics are likely to produce such effects. Many of these drugs may also be effective against nausea, emesis, and pruritus. (12 Dec 1998) |
| antipsychotic agents, butyrophenone | Those butyrophenone derivatives used in the treatment of psychoses. (12 Dec 1998) |
| antipsychotic agents, phenothiazine | Phenothiazine derivatives used in the treatment of psychoses. (12 Dec 1998) |
| adrenergic blocking agent | A compound that selectively blocks or inhibits responses to sympathetic adrenergic nerve activity (sympatholytic agent) and to epinephrine, norepinephrine, and other adrenergic amines (adrenolytic agent); two distinct classes exist, alpha-and beta-adrenergic receptor blocking agent's. (05 Mar 2000) |
| adrenergic neuronal blocking agent | A drug that prevents the release of norepinephrine from sympathetic nerve terminals; it does not inhibit the responses of the adrenergic receptors to circulating epinephrine, norepinephrine, and other adrenergic amines. (05 Mar 2000) |
| agent | <pharmacology> Any power, principle or substance capable of producing an effect, whether physical, chemical or biological. Origin: L. Agens = acting (18 Nov 1997) |
| agent, antihypertensive | As the name suggests, a drug aimed at reducing high blood pressure (hypertension). (12 Dec 1998) |
| agent, anti-infective | Something capable of acting against infection, by inhibiting the spread of an infectious agent or by killing the infectious agent outright. (12 Dec 1998) |
| Agent Orange | An herbicide and defoliant, consisting of (2,4,5-trichlorophenoxy)acetic acid, (2,4-dichlorophenoxy)acetic acid, and dioxin, that was widely used in the Vietnam War; it has been shown to possess residual post-exposure carcinogenic and teratogenic properties in humans. (05 Mar 2000) |
| agent, tocolytic | A medication that can inhibit labour, slow down or halt the contractions of the uterus. Tocolytic agents are widely used today to treat premature labour and permit pregnancy to procede and so let the foetus gain in size and maturity before being born. (12 Dec 1998) |
| alkylating agent | <oncology, pharmacology> A reagent that places an alkyl group, for example propyl in place of a nucleophilic group in a molecule. Alkylating reagents include a number of cytotoxic drugs some of which react fairly specifically with N7 of the purine ring and lead to depurination of DNA, for example the agent ethyl ethanesulphonic acid and thus to mutagenesis. The drugs interaction with DNAand prevents the division of the cells. Examples of drugs include: busulphan, chlorambucil, cyclophosphamide, melphalan. (29 Sep 1997) |