Review Question - QID 100929

Ipratropium competitively blocks the binding of acetylcholine to muscarinic receptors and is therefore most similar to the drug in question.

Asthma medications can be divided into two groups: reliever and controller medications. Reliever medications are used as needed to quickly relieve symptoms and consist of short-acting inhaled beta-2 agonists (albuterol) and inhaled anticholinergics (ipratropium). Controller medications are taken daily to decrease the frequency of exacerbations and are utilized depending on the severity of the asthma. These consist of inhaled/intravenous corticosteroids, long acting beta-2 agonists (salmeterol), cromolyn, theophyllin, leukotriene modifiers (zafirlukast), and Anti-IgE medications.

Elward et al. describe medical therapy for asthma. Inhaled corticosteroids are the preferred controller medication. For mild persistent asthma, leukotriene receptor antagonists are an alternative because they are easy to use, have high rates of compliance, and can provide good symptom control. Using short-acting beta-2 agonists more than two days per week or more than two nights per month generally indicates the need to intensify controller therapy.

Restrepo details the use of inhaled anticholinergic agents in obstructive airway disease. Anticholinergic agents are first-line medications in COPD and, to a lesser extent, in asthma. One theory for increased effectiveness in COPD as compared with asthma is that the vagal tone appears to be the only reversible component of airflow limitation in COPD. The inhaled anticholinergics approved for use include ipratropium bromide, oxitropium bromide, and tiotropium bromide.

Illustration A: Diagram detailing synthesis of leukotrienes and prostaglandins from phospholipids and diacylglycerol.

Incorrect answers:
Answer 1: Theophylline is both a competitive phosphodiesterase inhibitor (raises cAMP) and a adenosine receptor antagonist.
Answer 2: The mechanism of action of cromolyn is not entirely known but may have to do with mast cell stabilization and inhibition of sensory responses in cells innervating the lungs.
Answer 3: Zafirlukast inhibits leukotrienes, fatty compounds produced by the immune system that cause inflammation in asthma and bronchitis, and constrict airways.
Answer 4: Prednisone is a steroid and acts by binding to nuclear receptors and affecting gene transcription.