Histamine-receptor antagonists Health Dictionary

The defense substance responsible for most inflammation. It is synthesized from the amino acid histidine and is secreted by mast cells, basophils, and blood platelets. It stimulates vasodilation, capillary permeability, muscle contraction of the bronchioles, secretions of a number of glands, and attracts eosinophils, the white blood cells that are capable of moderating the inflammation. Mast cell histamine release is what usually causes allergies.... histamine

(1) Organs, which may consist of one cell or a small group of cells, that respond to di?erent forms of external or internal stimuli by conveying impulses down nerves to the CENTRAL NERVOUS SYSTEM, alerting it to changes in the internal or external environment.

(2) A small, discrete area on the cell membrane or within the cell with which molecules or molecular complexes (e.g. hormones, drugs, and other chemical messengers) interact. When this interaction takes place it initiates a change in the working of the cell.... receptor

A site on the membrane surrounding a cell (see CELLS) that binds to the hormone OESTROGENS. This activates the cell’s reaction to the hormone. Anti-oestrogen drugs such as TAMOXIFEN used to treat breast cancer (see BREASTS, DISEASES OF) prevent the oestrogen from binding to these receptors.... oestrogen receptor

These are drugs that block the action of HISTAMINE at the H2 receptor (which mediates the gastric and some of the cardiovascular effects of histamine). By reducing the production of acid by the stomach, these drugs – chie?y cimetidine, ranitidine, famotidine and nizatidine – are valuable in the treatment of peptic ulcers (healing when used in high dose; preventing relapse when used as maintenance therapy in reduced dose), re?ux oesophagitis (see OESOPHAGUS, DISEASES OF), and the ZOLLINGERELLISON SYNDROME. These drugs are now being supplanted by PROTON-PUMP INHIBITORS and HELICOBACTER PYLORI eradication therapy. (See also DUODENAL ULCER.)... h2 receptor antagonists

A group of drugs used in the treatment of hypertension (high blood pressure). They have a similar action to ACE inhibitors but do not cause a dry cough. Examples are losartan and valsartan.... angiotensin ii antagonists

A group of antiallergy drugs, such as montelukast and zafirlukast, used to prevent symptoms of mild to moderate asthma. The drugs work by blocking the effects of leukotrienes – naturally occurring substances released in the lungs during an allergic reaction.

Because they are not bronchodilator drugs, and will not relieve an existing attack, they are usually used with bronchodilators and inhaled corticosteroids to reduce the frequency of attacks.

Side effects include gastrointestinal disturbances and headache.

Skin and hypersensitivity reactions may also occur.... leukotriene receptor antagonists

A group of drugs used to treat the nausea and vomiting caused by radiotherapy and anticancer drugs. They are also used to control nausea and vomiting following surgery. Common serotonin antagonists include granisetron and ondansetron.... serotonin antagonists

(EGFR) a protein on the surface of cells (see receptor) that binds with epidermal *growth factor and is therefore involved in cell division. EGFR is expressed at increased levels in numerous tumours, particularly of the head and neck, and in colorectal cancer, in which it can be a target for antibody therapy with *cetuximab. *Tyrosine kinase inhibitors acting specifically on the EGFR include gefitinib and erlotinib in lung and pancreatic cancer.... epidermal growth factor receptor

a group of drugs used in the treatment of type 2 diabetes. They mimic the actions of *glucagon-like peptide-1 in regulating the rise in blood glucose levels after eating and they also enhance satiety (see incretin). As these drugs respond to a falling blood glucose level there is a reduced tendency to *hypoglycaemia compared with *sulphonylurea drugs and insulin therapy itself. They are given by subcutaneous injection and three of them are licensed for use in the UK: exenatide (Byetta; twice daily dosing), liraglutide (Victoza; once daily dosing), and lixisenatide (Lyxumia; once daily dosing).... glp-1 receptor agonists

a derivative of *histamine that was formerly used to test for acid secretion in the stomach in conditions involving abnormal gastric acid secretion, such as *Zollinger-Ellison syndrome.... histamine acid phosphate

one of a class of drugs that prevent the action of *leukotrienes by blocking their receptors on cell membranes, such as those in the airways. These drugs are used in the management of asthma for their effects in relaxing the smooth muscle of the airways and in reducing inflammation in the bronchial linings. Examples are montelukast and zafirlukast; side-effects may include headache and abdominal pain or gastrointestinal upsets.... leukotriene receptor antagonist

a receptor on synapses that binds the *neurotransmitter glutamate and also binds its *agonist NMDA (N-methyl-D-aspartate). This receptor is involved in learning, memory, mood, and cognition; its overactivity is associated with chronic pain. NMDA-receptor antibodies are associated with an *encephalitis preceded by psychiatric symptoms, often in patients with ovarian malignancy (teratoma). NMDA-receptor antagonists (e.g. *amantadine, *memantine hydrochloride, *riluzole) are used in the treatment of (among other conditions) epilepsy, Alzheimer’s disease, and chronic pain syndromes.... nmda receptor

see anti-oestrogen.... oestrogen-receptor antagonist

(PRRT) a type of radiotherapy used to treat neuroendocrine tumours (NETs; see neuroendocrine system). A *radionuclide is combined with a relevant *peptide to create a so-called radiopeptide, which is injected into the patient’s bloodstream. Because NETs have an overexpression of peptide receptors, the radiopeptide binds to the tumour, delivering a high dose of radiation directly to the cancer cells. The chief merit of PRRT is this ability to target delivery of radionuclides for highly localized treatment. A similar technique, using a gamma emitter as the radionuclide, can be used for locating and imaging NETs.... peptide receptor radionuclide therapy

a cell or group of cells found between muscle fibres that responds to stretching of the muscle by transmitting impulses to the central nervous system through the sensory nerves. Stretch receptors are part of the *proprioceptor system necessary for the performance of coordinated muscular activity.... stretch receptor

autoantibodies targeted against the *thyroid-stimulating hormone (TSH) receptor of the thyroid cells. They can activate the TSH receptor, leading to the hyperthyroidism of *Graves’ disease, or they can block the TSH receptor, causing *hypothyroidism.... tsh receptor antibodies