Terbutaline: A selective beta-2 adrenergic agonist used as a bronchodilator and tocolytic.Adrenergic beta-Agonists: Drugs that selectively bind to and activate beta-adrenergic receptors.Tocolytic Agents: Drugs that prevent preterm labor and immature birth by suppressing uterine contractions (TOCOLYSIS). Agents used to delay premature uterine activity include magnesium sulfate, beta-mimetics, oxytocin antagonists, calcium channel inhibitors, and adrenergic beta-receptor agonists. The use of intravenous alcohol as a tocolytic is now obsolete.Nebulizers and Vaporizers: Devices that cause a liquid or solid to be converted into an aerosol (spray) or a vapor. It is used in drug administration by inhalation, humidification of ambient air, and in certain analytical instruments.Bronchodilator Agents: Agents that cause an increase in the expansion of a bronchus or bronchial tubes.Administration, Inhalation: The administration of drugs by the respiratory route. It includes insufflation into the respiratory tract.Budesonide: A glucocorticoid used in the management of ASTHMA, the treatment of various skin disorders, and allergic RHINITIS.Adrenergic beta-2 Receptor Agonists: Compounds bind to and activate ADRENERGIC BETA-2 RECEPTORS.Aerosols: Colloids with a gaseous dispersing phase and either liquid (fog) or solid (smoke) dispersed phase; used in fumigation or in inhalation therapy; may contain propellant agents.Butoxamine: A beta-2 selective adrenergic antagonist. It is used primarily in animal and tissue experiments to characterize BETA-2 ANDRENERGIC RECEPTORS.Ethanolamines: AMINO ALCOHOLS containing the ETHANOLAMINE; (-NH2CH2CHOH) group and its derivatives.Peak Expiratory Flow Rate: Measurement of the maximum rate of airflow attained during a FORCED VITAL CAPACITY determination. Common abbreviations are PEFR and PFR.Pregnenediones: Unsaturated pregnane derivatives containing two keto groups on side chains or ring structures.Asthma: A form of bronchial disorder with three distinct components: airway hyper-responsiveness (RESPIRATORY HYPERSENSITIVITY), airway INFLAMMATION, and intermittent AIRWAY OBSTRUCTION. It is characterized by spasmodic contraction of airway smooth muscle, WHEEZING, and dyspnea (DYSPNEA, PAROXYSMAL).Albuterol: A short-acting beta-2 adrenergic agonist that is primarily used as a bronchodilator agent to treat ASTHMA. Albuterol is prepared as a racemic mixture of R(-) and S(+) stereoisomers. The stereospecific preparation of R(-) isomer of albuterol is referred to as levalbuterol.Metaproterenol: A beta-2 adrenergic agonist used in the treatment of ASTHMA and BRONCHIAL SPASM.Fenoterol: An adrenergic beta-2 agonist that is used as a bronchodilator and tocolytic.Receptors, Adrenergic, beta-2: A subclass of beta-adrenergic receptors (RECEPTORS, ADRENERGIC, BETA). The adrenergic beta-2 receptors are more sensitive to EPINEPHRINE than to NOREPINEPHRINE and have a high affinity for the agonist TERBUTALINE. They are widespread, with clinically important roles in SKELETAL MUSCLE; LIVER; and vascular, bronchial, gastrointestinal, and genitourinary SMOOTH MUSCLE.Forced Expiratory Volume: Measure of the maximum amount of air that can be expelled in a given number of seconds during a FORCED VITAL CAPACITY determination . It is usually given as FEV followed by a subscript indicating the number of seconds over which the measurement is made, although it is sometimes given as a percentage of forced vital capacity.ButylaminesPrenalterol: A partial adrenergic agonist with functional beta 1-receptor specificity and inotropic effect. It is effective in the treatment of acute CARDIAC FAILURE, postmyocardial infarction low-output syndrome, SHOCK, and reducing ORTHOSTATIC HYPOTENSION in the SHY-RAGER SYNDROME.Maximal Expiratory Flow Rate: The airflow rate measured during the first liter expired after the first 200 ml have been exhausted during a FORCED VITAL CAPACITY determination. Common abbreviations are MEFR, FEF 200-1200, and FEF 0.2-1.2.Capillary Leak Syndrome: A condition characterized by recurring episodes of fluid leaking from capillaries into extra-vascular compartments causing hematocrit to rise precipitously. If not treated, generalized vascular leak can lead to generalized EDEMA; SHOCK; cardiovascular collapse; and MULTIPLE ORGAN FAILURE.Magnetocardiography: The measurement of magnetic fields generated by electric currents from the heart. The measurement of these fields provides information which is complementary to that provided by ELECTROCARDIOGRAPHY.Chlorofluorocarbons: A series of hydrocarbons containing both chlorine and fluorine. These have been used as refrigerants, blowing agents, cleaning fluids, solvents, and as fire extinguishing agents. They have been shown to cause stratospheric ozone depletion and have been banned for many uses.Double-Blind Method: A method of studying a drug or procedure in which both the subjects and investigators are kept unaware of who is actually getting which specific treatment.Receptors, Adrenergic, beta: One of two major pharmacologically defined classes of adrenergic receptors. The beta adrenergic receptors play an important role in regulating CARDIAC MUSCLE contraction, SMOOTH MUSCLE relaxation, and GLYCOGENOLYSIS.Powders: Substances made up of an aggregation of small particles, as that obtained by grinding or trituration of a solid drug. In pharmacy it is a form in which substances are administered. (From Dorland, 28th ed)