| opioid partial agonist | <pharmacology> A compound that has an affinity for and stimulates physiologic activity at the same cell receptors as opioid agonists but that produces only a partial (i.e., submaximal) bodily response. (16 Dec 1997) |
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| agonist | 1. <anatomy> A prime mover. 2. <pharmacology> A drug that has affinity for and stimulates physiologic activity at cell receptors normally stimulated by naturally occurring substances, thus triggering a biochemical response. (18 Nov 1997) |
| calcium channel agonist | <pharmacology> Agents that increase calcium influx into calcium channels of excitable tissues. This causes vasoconstriction in vascular smooth muscle and/or cardiac muscle cells as well as stimulation of insulin release from pancreatic islets. Therefore, tissue-selective calcium agonists have the potential to combat cardiac failure and endocrinological disorders. They have been used primarily in experimental studies in cell and tissue culture. (12 Dec 1998) |
| receptor agonist | A substance that mimics a specificneurotransmitter, is able to attach to that neurotransmitter's receptor and thereby produces the same action that theneurotransmitter usually produces. Drugs are often designed as receptor agonists to treat a variety of diseases and disorders whenthe original chemical substance is missing or depleted. (22 May 1997) |
| 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) |
| muscarinic agonist | Drugs that bind to and activate muscarinic cholinergic receptors (receptors, muscarinic). Muscarinic agonists are most commonly used when it is desirable to increase smooth muscle tone, especially in the GI tract, urinary bladder and the eye. They may also be used to reduce heart rate. (12 Dec 1998) |
| histamine agonist | Drugs that bind to and activate histamine receptors. Although they have been suggested for a variety of clinical applications histamine agonists have so far been more widely used in research than therapeutically. (12 Dec 1998) |
| opioid agonist | <pharmacology> Any morphine-like compound that produces bodily effects including pain relief, sedation, constipation and respiratory depression. (16 Dec 1997) |
| LH and RH agonist | <pharmacology> Particular medications that act as potent inhibitors of gonadotrophin (testosterone) secretion. They act to inhibit the production of testosterone through a feedback mechanism on the pituitary gland. LH and RH agonists are useful in the treatment of prostate cancer. (14 Oct 1997) |
| activity | 1. The state of being active, the ability to produce some effect, the extent of some function or action. 2. <chemistry> A thermodynamic quantity that represents the effective concentration of a solute in a nonideal solution, if concentrations are replaced by activities, the equations for equilibrium constants, electrode potentials, osmotic pressure, boiling point elevation, freezing point depression and vapour pressures of volatile solutes are converted from approximations that hold only for dilute solutions to exact equations that hold for all concentrations. The activity is equal to the product of the concentration and the activity coefficient, a dimensionless number measuring deviation from nonideality. Symbol a. The potential or true thermodynamic activity of a substance, as opposed to its molar concentration. 3. <radiobiology> The number of nuclear transitions or disintegrations occurring in a given quantity of radioactive material per unit time. The SI unit of activity is s-1. The special name for the unit of activity is becquerel (Bq). The previously used special unit of activity, curie (Ci), is being replaced by the becquerel. 1 Bq = 2.7 x E-11 Ci. 1 Ci = 3.7 x E10 Bq. 4. Optical activity. (16 Dec 1997) |
| activity coefficient | <chemistry> The factor by which the value of a concentration of a solute must be multiplied to determine its true thermodynamic activity. (06 May 1997) |
| activity cycles | Bouts of physical irritability or movement alternating with periods of quiescence. It includes biochemical activity and hormonal activity which may be cellular. These cycles are shorter than 24 hours and include sleep-wakefulness cycles and the periodic activation of the digestive system. (12 Dec 1998) |
| activity, drug | A measure of the physiological response a drug produces in the body. A less active drug produces less response (and visa versa). (12 Dec 1998) |
| blocking activity | The repression or elimination of electrical activity in the brain by the arrival of a sensory stimulus. (05 Mar 2000) |
| blood bactericidal activity | Native bactericidal property of blood due to normally occurring antibacterial substances such as beta lysin, leukin, etc. (12 Dec 1998) |