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RespiRatoRy ` RESPIRATORY—PhARmACOlOgY RespiRatoRy ` RESPIRATORY—PhARmACOlOgY seCtioN iii 687

Asthma drugs Bronchoconstriction is mediated by (1) inflammatory processes and (2) parasympathetic tone;
therapy is directed at these 2 pathways.
β -agonists Albuterol—relaxes bronchial smooth muscle (short acting β -agonist). For acute exacerbations. Can
2 2
cause tremor, arrhythmia.
Salmeterol, formoterol—long-acting agents for prophylaxis. Can cause tremor, arrhythmia.
Inhaled Fluticasone, budesonide—inhibit the synthesis of virtually all cytokines. Inactivate NF-κB, the
corticosteroids transcription factor that induces production of TNF-α and other inflammatory agents. 1st-line
therapy for chronic asthma. Use a spacer or rinse mouth after use to prevent oral thrush.
Muscarinic Tiotropium, ipratropium—competitively block muscarinic receptors, preventing
antagonists bronchoconstriction. Also used for COPD. Tiotropium is long acting.
Antileukotrienes Montelukast, zafirlukast—block leukotriene Exposure to antigen
receptors (CysLT1). Especially good for (dust, pollen, etc)
aspirin-induced and exercise-induced asthma.
Zileuton—5-lipoxygenase pathway inhibitor. Avoidance
Blocks conversion of arachidonic acid to
leukotrienes. Hepatotoxic.
Antigen and IgE Omalizumab
Anti-IgE monoclonal Omalizumab—binds mostly unbound serum on mast cells
therapy IgE and blocks binding to FcεRI. Used in
allergic asthma with  IgE levels resistant to Steroids
inhaled steroids and long-acting β -agonists. Chromones
2
Methylxanthines Theophylline—likely causes bronchodilation by
inhibiting phosphodiesterase Ž  cAMP levels Mediators
due to  cAMP hydrolysis. Limited use due (leukotrienes, histamine, interleukins, etc)
to narrow therapeutic index (cardiotoxicity,
neurotoxicity); metabolized by cytochrome β-agonists
P-450. Blocks actions of adenosine. Theophylline Steroids
Muscarinic Antileukotrienes
Chromones Cromolyn—prevents mast cell degranulation. antagonists Anti-IL-5
Prevents acute asthma symptoms. Rarely used. monoclonal
antibodies
Anti-IL-5 monoclonal Prevents eosinophil differentiation, maturation,
therapy activation, and survival mediated by IL-5 Early response: Late response:
stimulation. For maintenance therapy in bronchoconstriction inflammation
severe eosinophilic asthma.
Mepolizumab, reslizumab—against IL-5.
Benralizumab—against IL-5 receptor α.
Bronchial
Symptoms
ATP hyperreactivity
Bronchodilation AC β-agonists

cAMP
Bronchial tone
PDE Theophylline
AMP
ACh Adenosine
Muscarinic Theophylline
antagonists
Bronchoconstriction

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