Week 7 Outline

Chapter 17: Drugs Affecting the Respiratory System

Bronchodilators

• BETA₂-RECEPTOR AGONISTS
  • Albuterol (ProAir, Ventolin, Proventil) *most common
  • metaproterenol (Alupent), terbutaline (Brethine, Brethaire), bitolterol (Tornalate), pirbuterol (Maxair), and levalbuterol (Xopenex) *short acting
  • arformoterol (Brovana), formoterol (Foradil), indacaterol (Arcapta), and salmeterol (Serevent) *long acting

 

Pharmacodynamics

• act on the smooth muscle of the bronchial tree to reverse bronchospasm, thereby decreasing airway resistance and residual volume and increasing vital capacity and airflow.
• stimulate beta2 adrenergic receptors in the lungs to increase production of cyclic adenosine monophosphate (cAMP) by activation of adenyl cyclase, the enzyme

that catalyzes the conversion of adenosine triphosphate (ATP) to cAMP.

• Increased cAMP concentrations relax bronchial smooth muscle and inhibit release of mediators of immediate hypersensitivity from cells, especially from the mast cells

effects

• all of the currently available preparations have some effects on other body systems (cardiovascular system, skeletal muscles, and CNS)
  • vasodilationàdecrease in diastolic BPà reflux tachycardia
  • increased heart rate

 

Contraindications & Precautions

• Contraindicationsà
  • Cardiac arrhythmias associated with tachycardia
  • heart block caused by digitalis intoxication
  • angina
  • narrow-angle glaucoma
  • organic brain damage (epinephrine only)
  • shock during general anesthesia with halogenated agents
• patients with hypertension, ischemic heart disease, coronary insufficiency, congestive heart failure, and a history of stroke and/or cardiac arrhythmias should be monitored closely for adverse effects during administration
• patients with DM, there is a potential drug-induced hyperglycemia that may result in loss of diabetic control àinsulin dosage may need to be increased
• patients with hyperthyroidism, adverse reactions are more likely to occur

• Patients taking digoxin require close monitoring when albuterol is started because it increases the volume of distribution of digoxin and can cause up to a 30% decrease in blood digoxin levels.
• FDA released a safety announcement regarding LABAs (Long acting beta agonists)à
  • To ensure the safe use of these products:
    • Single-ingredient LABAs should only be used in combination with an asthma controller medication; they should not be used alone.
    • should only be used long-term in patients whose asthma cannot be adequately controlled on asthma controller medications.
    • should be used for the shortest duration of time required to achieve control of asthma symptoms and discontinued, if possible, once

asthma control is achieved. Patients should then be maintained on an asthma controller medication.

• Pediatric and adolescent patients who require the addition of a

LABA to an inhaled corticosteroid should use a combination product

containing both an inhaled corticosteroid and a LABA, to ensure compliance with both medications