Flashcards in Pharm 47 - Asthma Deck (53)
Two ways asthma medications work?
1) By relaxing bronchial smooth muscle
2) By preventing and treating inflammation
How does the autonomic system regulate smooth muscle?
Sympathetic (adrenergic) tone causes bronchodilation; Parasympathetic (cholinergic) tone causes bronchoconstriction; Nonadrenergic, noncholinergic (NANC) fibers also innervate the respiratory tree
What is the main type of receptor expressed on airway smooth muscle cells? What chemical activates them?
Beta2-adrenergic receptors are activated by epinephrine, which is secreted by the adrenal medulla -> causes bronchodilation
How do parasympathetics create effects in the lungs?
Muscarinic (M3) receptors on airway smooth muscles are stimulated by acetylcholine -> causes bronchoconstriction
How do NANC fibers create effects?
NANC fibers are primarily under parasympathetic control. They are either stimulatory (cause bronchoconstriction) or inhibitory (cause bronchodilation). They release Neurokinin A, Calcitonin gene-related peptide, substance P, bradykinin, tachykinin, and neuropeptide Y to bronchoconstrict. NO and VIP cause bronchorelaxation.
What is more potent than histamine at producing bronchoconstriction?
What are the two categories of asthma medications?
1) Relievers (bronchodilators)
2) Controllers/Preventers (anti-inflammatory)
Antagonists at muscarinic receptors on airway smooth muscle and glands -> decreased bronchoconstriction and mucus secretion
Name the Anticholinergics (2)
Ipratropium, Tiotropium (long duration of action)
Anticholinergic clinical applications (3)
Asthma (not approved by FDA), COPD, Rhinitis
Adverse Effects Include Paralytic ileus, angioedema, bronchospasm; also abnormal taste, dry mouth/nasal mucus, constipation, tachycardia, urinary retention; if accidentally squirted in eye, can cause mydriasis and increased intraocular pressure -> angle-closure glaucoma
Hypersensitivity to drug or to soya lecithin
Has long duration of action b/c of slow dissociation from M1/M3 receptors
Agonists at Beta-adrenergic receptors; act through stimulatory G protein to cause smooth muscle relaxation and bronchodilation
Beta-Adrenergic Agonist MOA
Used for asthma, anaphylaxis, cardiac arrest, open-angle glaucoma
Epinephrine (class and clinical applications)
Adverse Effects Include arrhythmias, hypertensive crisis, pulmonary edema; also tachycardia, palpitations, sweating, N/V, tremor, nervousness, dyspnea
Contraindications Include Narrow-angle glaucoma (opthalmic form), MAOI use w/in 2 weeks (inhaled form)
Non-selective agonist binds alpha (HTN), beta1 (cardiac stimulation), and beta2 (bronchodilation) adrenergic receptors
Used for asthma, cardiac arrest, decreased vascular flow, heart block, shock, Stokes-Adams syndrome
Adverse effects include Tachyarrythmia, palpitations, dizziness, HA, tremor, restlessness
Contraindications include Tachyarrythmias, angina, digitalis-induced tachycardia/heart block
Binds beta 1 (cardiac stimulation) and beta 2 (bronchodilation) adrenergic receptors
Isoproterenol therapeutic considerations
Irritating list of Selective Beta2 Receptor Agonists (7)
Metaproterenol, Albuterol (Salbutamol), Levalbuterol, Terbutaline, Pirbuterol, Isoetharine, Bitolterol (MALTs with mr. PIB)
Selective Beta2 Receptor Agonists clinical applications
adverse effects include Tachyarrythmia, palpitations, dizziness, HA, tremor, restlessness (BUT less cardiac effects since they're Beta2 selective)
Selective Beta2 Receptor Agonists and M[E/O]TEROLs
Selective Beta2 Receptor Agonists therapeutic considerations
Terbutaline, albuterol, pirbuterol, and bitolterol cause fewer cardiac effects; Levalbuterol is more Beta2 selective than albuterol
-M[E/O]TEROLs (class and clinical applications)
COPD (formoterol, salmeterol, arformoterol); Asthma (formoterol, salmeterol)
Long acting (LABAs) (12-24 hours); Should not be used as asthma monotherapy b/c of increased risk of death from asthma (use with inhaled corticosteroid)
-M[E/O]TEROLs therapeutic considerations
MOA Nonselective phosphodiesterase inhibitors, prevent degradation of cAMP, act as adenosine receptor antagonist -> smooth muscle relaxation and bronchodilation