NR 566 Week 2 Study Guide {2022} | Chapter 17: Drugs Affecting the Respiratory System

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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 in asthma for all ages o Two-fold increase in catastrophic events (asthma-related intubations and death) o The use of LABAs is contraindicated without the use of an asthma controller medication such as an inhaled corticosteroid o Only use long-term in patients who asthma cannot be adequately controlled on asthma controller medications o Use for the shortest duration of time required to achieve control, then maintain on an asthma controller medication o Pediatric and adolescent patient who require addition of a LABA to an inhaled corticosteroid should be a combination product containing both an inhaled ICS and a LABA, to ensure compliance with both medications • Terbutaline pregnancy category B (prevent contractions) (others category C) • Albuterol safe for all age children • Metaproterenol can be used in young children • Levalbuterol, as young as 2 (drug insert says 6) • Salmeterol should not be used in children less than age 4 years and never singly. • Formoterol age 5 and older • Indacaterol and aformoterol are used for COPD, not for use in children or adolescents Drug and Food Interactions o Many drug interactions o Digitalis glycosides: increased risk of dysrhythmia o Beta adrenergic blocking agents (Beta Blockers): direct competition for beta sites resulting in mutual inhibition of therapeutic effects o Including beta blocker eye drops o Tricyclic antidepressants and MAOIs potentiate effects of beta agonist on vascular system ADRs o Usually transient o Stopping the med is not usually needed, reduce dose then slowly increase o Supraventricular and ventricular ectopic beats have occurred o Tachycardia and palpitations o Some central nervous system (CNS) excitation effects o Tremors, dizziness, shakiness, nervousness, and restlessness o Headaches, rarely insomnia, post inhalation cough o Salmeterol has an increased risk of exacerbation of severe asthma symptoms if the patient is deteriorating o Overuse can lead to seizures, hypokalemia, anginal pain and HTN o Stimulant like effects o GI upset, take po meds with food Clinical Use and Dosing Bronchospasm • Bronchodilators are used primarily in the treatment of bronchospasm associated with asthma, bronchitis (acute or chronic), and chronic obstructive pulmonary disease (COPD) o Albuterol  MDI dose children over 4 and adults is 2 puffs every 4 to 6 hours o Nebulizer dose children over age 12 and adults is 2.5 mg/dose  For younger children over 15 kg, dose is 0.1 to 0.15 mg/kg/dose o Dose may be repeated once a [Show More]

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