Week 4 notes6 - T reatment of Brochospastic Disorders...

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Treatment of Brochospastic Disorders Bronchospasm is treated with bronchodilators, which are often needed to provide immediate, as well as long-lasting, relief of dyspnea from primary lung disorders. This category of drugs includes Beta-2 receptor agonists (short-acting and long- acting), anticholinergics, and methylxanthines in a variety of aerosol, oral and I.V. formulations. List of Available Beta-2 Receptor Agonist Bronchodilators Short-acting -epinephrine (Adrenalin) (Asthma-haler) (Primatene) (Sus-phrine) (many others) -albuterol (Ventolin) (Proventil) -levalbuterol (Xopenex) -metaproterenol (Alupent) (Metaprel) -pirbuterol acetate (Maxair Autohaler) -terbutaline (Brethine) (Brethair) Long-acting -salmeterol (Serevent) -formoterol (Foradil) Pharmacodynamics of the Beta-2 Receptor Agonist Bronchodilators As the name implies, these drugs have affinity and intrinsic activity on Beta-2 receptors located on the smooth muscle cells of the bronchi and bronchioles. Activation of these receptors induces relaxation in the smooth muscles that results in bronchodilation in patients who have any degree of bronchospasm (bronchoconstriction). [Note: Some of these drugs, in addition to activating Beta-2 receptors, also activate some of the other adrenergic receptors. These aspects of the drugs will be discussed with each individual drug.] Individual Beta-2 Receptor Agonist Bronchodilator Drugs EPINEPHRINE - PHARMACODYNAMICS o In addition to activating Beta-2 receptors, epinephrine also activates Alpha-1, Alpha-2, and Beta-1 receptors. - PHARMACOKINETICS 1
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Treatment of Brochospastic Disorders o Epinephrine is administered parenterally, topically, subcutaneously, and by inhalation. It is metabolized at nerve endings and (to a slight degree) in the liver. There is no appreciable excretion but when it does occur it is found in the urine. - ADVANTAGES o Useful in the bronchospasm associated with anaphylaxis, especially because of the cardiovascular benefits it also provides o Rapid onset of action by inhalation (3-5 min.) and by the parenteral route (5-10 min.); most useful in the therapy of acute bronchospasm. o Available over-the-counter; the preparation Primatene is available as an O.T.C. product, increasing patient access to it. - DISADVANTAGES o Tachycardia and palpitations; this results from activation of Beta-1 receptors. Some of this is a reflex that results from activation of Beta-2 receptors of the smooth muscle cells on the arteries of the skeletal muscles. This causes a brief decrease in peripheral resistance by causing vasodilatation in these vascular beds. The heart compensates for this by suddenly increasing heart rate. o Muscle tremors; this is secondary to activation of both Beta-1 and Beta-2 receptors. o Hypertension; this is the result of activation of Alpha-1 receptors and the
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This note was uploaded on 05/19/2011 for the course NURSING 517/617 taught by Professor Lipstate during the Spring '11 term at University of Louisiana at Lafayette.

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Week 4 notes6 - T reatment of Brochospastic Disorders...

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