Bronchodilators

• B2RA overview


  bronchodilators used to treat reversible vasoconstriction caused by COPD or asthma
• B2RA examples


  Rapid acting: Albuterol, metaproterenol, terbutaline, pirbuterol, levalbuterol

  long acting: aformoterol, formoterol, salmeterol

  ultra long acting: indacaterol, olodaterol, vilanterol
• B2RA pharmacodynamics


  stimulate beta 2 adrenergic receptors in the lungs to increase cAMP production resulting in relaxation of bronchial smooth muscle. cAMP also inhibits production of hypersensitive molecules produced by mast cells
• B2RA action

  Stimulate beta 2 adrenergic receptors to increase cAMP which leads to relaxation of bronchial smooth muscle and inhibits release of mediators of hypersensitivity from mast cells

  B2RAs also work on other systems causing various adverse effects
• Albuterol action

  selective beta2 agonist with some beta1 activity. Increases heart rate by directly stimulating beta2 receptors in the heart and vascular smooth muscles. stimulation of vascular smooth muscle leads to vasodilation and decrease in blood pressure which causes reflex tachycardia.

  Albuterol can also cause tremors due to skeletal muscle activation

  drug of choice for first-line therapy due to least amount of adverse effects
• Levalbuterol and pirbuterol


  similar to albuterol
• terbutaline

  selective beta2 agonist. Can inhibit uterine contractions
• long acting inhaled bronchodilators

  almeterol, formoterol, arformoterol

  half life of 10-12 hours

  salmeterol is more selective, formoterol works more effectively, arformoterol works even more effectively than both
• ultra long acting bronchodilators

  indacaterol, olodaterol, vilanterol

  half lives of 21.3-45 hours

  are highly selective for beta 2
• Precautions of bronchodilators

  • Contraindication in cardiac arrhythmias, especially tachycardia, heart block
  • Caution in HTN, ischemic heart disease, CHF, stroke
  • Caution in diabetics due to risk of hypoglycemia r/t bronchodilator use
  • Caution in older adults
• LABA

  Long-acting beta agonists
• LABA are contraindicated without co use of inhaled corticosteroid
• LABA are only for long term asthma patients without managed symptoms
• LABAs should be discontinued if possible
• Pediatric and Adolescents should use combined LABA/corticosteroid rather than separate medications
• Terbutaline is safe in pregnancy
• Albuterol is used safely in children
• Bronchodilator adverse drug reactions

  generally transient

  supraventricular ectopic beats with inhalation, tachycardia and palpitations

  CNS excitation such as tremors, dizziness, shakiness, nervousness

  Headaches

  insomnia but rare

  post-inhalation cough

  increased risk of asthma symptoms with only LABA use
• Bronchodilator drug interactions

  Caution in patients on any medications that treat heart arrhythmias

  beta blockers may counteract the effect of beta2 agonists

  TCAs and MAOIs may potentiate bronchodilator

  diuretics or other drugs that lower potassium may lead to hypokalemia or ECG changes due to potentiating effects by B2RA
• Albuterol dosing

  2 puffs every 4 to 6 hours

  can also be given via nebulizer

  may be repeated after 5-10 minutes up to 3 times total
• Arformoterol dosing

  via nebulizer, 15 mcg inhalation x2 day

  not approved for children and is not a rescue medication
• Indacaterol dosing


  powder via inhaler device

  one capsule per day
• Bronchodilators can be used prior to exercising to prevent exercise induced asthma