Dictionary

anti-infective An agent that is capable of acting against infection, either by inhibiting the spread of an infectious agent or by killing the infectious agent outright.

antihypertensive A medication or another substance that reduces high blood pressure (hypertension). See also high blood pressure.

antihistamine A drug that opposes the action of histamine released during an allergic reaction by blocking the action of the histamine on the tissue. Antihistamines frequently cause dry mouth and sleepiness. Some antihistamines are nonsedating. Antihistamine side effects that may occur include urine retention in males and increased heart rate.

antiphospholipid syndrome An immune disorder characterized by the presence of abnormal antibodies in the blood that are directed against the chemical structure of fats that contain phosphorus (phospholipids). Abbreviated APS. APS is associated with abnormal blood clotting, migraine headaches, recurrent pregnancy loss, and low blood platelet counts (thrombocytopenia). APS can occur by itself (primary APS)…

antigen, prostate specific See prostate specific antigen test.

antigen A substance that the immune system perceives as being foreign or dangerous. The body combats an antigen with the production of an antibody.

antifungal A medication that limits or prevents the growth of yeasts and other fungal organisms.

antidote A drug that counteracts a poison.

antiDNAse B A blood test for antibodies to the streptococcus B bacteria.

antidiuretic hormone A peptide hormone made in the hypothalamus and released at the base of the brain by the nearby pituitary gland. Abbreviated ADH. ADH prevents the production of dilute urine and is therefore antidiuretic. It can also stimulate contraction of arteries and capillaries, and it may have effects on mental function. Also known as…

antidepressant A medication that prevents or reduces the symptoms of clinical depression. Some antidepressants may also be prescribed for their other medical effects, including increasing blood flow within the brain and treating chronic pain. See also MAO inhibitor; SSRI; tricyclic antidepressant.

anticoagulant An agent that is used to prevent the formation of blood clots. Anticoagulants have various uses. Some are used for the prevention or treatment of disorders characterized by abnormal blood clots and emboli. Anticoagulant drugs include intravenous heparin, which acts by inactivating thrombin and several other clotting factors that are required for a clot…