NR566 Week 2 Study Guide

NR566 Week 2 Study Outline Chapter 17: Drugs Affecting the Respiratory System Bronchodilators: Beta 2 Receptor Agonists (B2RA): Short and long acting beta agonists • B2RA widely used in all ages to treat reversible bronchoconstriction caused by reactive airway disease (RAD) or COPD • Bronchodilators • Short-acting beta agonists: Albuterol (ProAir, Ventolin, Proventil) , metaproterenol (Alupent),  terbutaline (Brethine, Brethaire), bitolterol (Tornalate), pirbuterol (Maxair), and levalbuterol (Xopenex)   • Long-acting beta agonists:  arformoterol (Brovana), salmeterol (Serevent), formoterol (Foradil), and indacaterol (Arcapta Neohaler)   • Drug of choice during pregnancy for asthma Pharmacodynamics    • Act on smooth muscle to reverse bronchospasm, decreases airway resistance and residual volume and increasing VC and airflow • Stimulate beta 2 adrenergic receptors in the lungs to increase cAMP production which relaxes bronchial smooth muscle and inhibits mediators from hypersensitivity cells (mast cells) • All beta agonists stimulate beta 1 activity (increased HR, tremor)f Short Acting Beta Agonists • Albuterol  o Selective beta2 agonist with minor beta1 activity  o Often first-line drug r/t less ADRs than the other drugs in this class o Increases HR by stimulating beta 2 receptors in the heart and vascular smooth muscle • Levalbuterol: (similar to albuterol), where the (S)-isomer from racemic albuterol is removed • Pirbuterol: selective beta 2 agonist, similar to albuterol • Terbutaline: similar to albuterol, selective beta 2 with minor beta 1 activity o Known to inhibit uterine contractions • Metaproterenol: beta 2 selective with some beta 1 activity, less selective than albuterol or terbutaline • Bitolterol: hydrolyzed by esterase in the lung to colterol, or terbutylnorepinephrine, selective beta 2 Long Acting Beta Agonists (Salmeterol, formoterol, indacaterol, and aformoterol) • Salmeterol is more selective for beta2 receptors than albuterol and has minor beta1 activity. o 12 hour half-life o Formoterol: 200-fold greater agonist activity at B2 than albuterol and has minor B1 activity o Aformoterol (R,R)-enantiomer of formoterol, twice as potent as formoterol o Indacaterol: 24 fold greater B2 activity than B1 o Salmeterol and formoterol exert long-lasting broncho protection against allergen, exercise, histamine, and methacholine caused bronchospasm Pharmacokinetics    • Contraindications: Cardiac arrhythmias (tachycardia or heart block caused by digitalis intoxication, angina, narrow-angle glaucoma, organic brain damage (epi only), and shock during general anesthesia with halogenated agents • Monitor closely: HTN, ischemic heart disease, coronary insufficiency, CGH, and Hx of stroke and/or cardiac arrhythmias • Diabetics: potential drug-induced hyperglycemia, insulin dose may need increased • Hyperthyroidism: ADRs are more likely to occur with use of bronchodilators • Digoxin: require close monitoring, albuterol increases the volume of distribution of dig and can cause decreased dig blood levels • Pheochromocytoma: avoid, severe HTN may occur • Older adults: Lower doses r/t increased sympathomimetic sensitivity • Black Box warning for LABAs: The risks of salmeterol (Serevent) and formoterol (Foradil) outweighed the benefits and should not be used singly