Respiratory System MCQs

Two approaches to interrupting the leukotriene pathway have been pursued: inhibition of 5-lipoxygenase, thereby preventing leukotriene synthesis; and inhibition of the binding of LTD 4 to its receptor on target tissues, thereby preventing its action. Reference: LANG’ Basic & clinical pharmacology by Bertram G. Katzung, Susen B. Masters and Anthony J. Trevor 12 th edition. Chapter 20- Drugs used in asthma by Dr. Homer A. Boushy, MD. Page no. 349

Oral rinsing after inhaled steroid use is the most appropriate recommendation. In bronchial asthma, the use of inhaled glucocorticoids such as mometasone results in more targeted steroid delivery to the lungs with much less systemic absorption. However, some of the drug is deposited in the oral cavity, which predisposes patients to local opportunistic fungal infections, especially candidiasis. Gargling or oral rinsing immediately after inhalation is recommended to reduce the local steroid burden and decrease the risk of infection. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 713

The methylxanthines have positive chronotropic and inotropic effects. At low concentrations, these effects appear to result from inhibition of presynaptic adenosine receptors in sympathetic nerves increasing catecholamine release at nerve endings. The higher concentrations (> 10 μmol/L, 2 mg/L) associated with inhibition of phosphodiesterase and increases in cAMP may result in increased influx of calcium. At much higher concentrations (> 100 μmol/L), sequestration of calcium by the sarcoplasmic reticulum is impaired. Reference: LANG’ Basic & clinical pharmacology by Bertram G. Katzung, Susen B. Masters and Anthony J. Trevor 12 th edition. Chapter 20- Drugs used in asthma by Dr. Homer A. Boushy, MD. Page no. 345

Ipratropium appears to be at least as effective in patients with COPD that includes a partially reversible component. A longer acting, selective antimuscarinic agent, tiotropium, is approved as a treatment for COPD. It binds to M1, M2, and M3 receptors with equal affinity, but dissociates most rapidly from M 2 receptors, expressed on the efferent nerve ending. This means that tiotropium does not inhibit the M2 -receptor–mediated auto–down-regulation of acetylcholine release, and thus confers a degree of receptor selectivity. Reference: LANG’ Basic & clinical pharmacology by Bertram G. Katzung, Susen B. Masters and Anthony J. Trevor 12 th edition. Chapter 20- Drugs used in asthma by Dr. Homer A. Boushy, MD. Page no. 347

Ipratropium appears to be least as effective in patients with COPD that includes a partially reversible component. A longer acting, selective, anti-muscarinic agent, tiotropium, is approved for treatment of COPD. Reference: LANG' Basic & Clinical Pharmacology by Bertram G. Katzung, Susen B. Masters and Anthony J. Trevor, 12th Edition, Page Number-347.

Oropharyngeal candidiasis (thrush) is the most common adverse effect of treatment with inhaled corticosteroids. It can be prevented by gargling with water after use of the inhaler and/or by adding a spacer to metered dose inhalers. This patient is experiencing symptoms at night and > 2 times per week on her current regimen of PRN albuterol (SABA). The addition of a daily, low-dose inhaled steroid to her regimen is the preferred management for mild asthma. Because inhaled corticosteroids do not take full effect until they have been used for approx. 1 week, a follow-up visit should be scheduled after this time to assess symptom control. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 709

Some patients appear to have particularly favourable responses, but no clinical features allow identification of “responders” before a trial of therapy. In the USA, zileuton is approved for use in an oral dosage of 1200 mg of the sustained-release form twice daily; zafirlukast, 20 mg twice daily; and montelukast, 10 mg (for adults) or 4 mg (for children) once daily. Reference: LANG’ Basic & clinical pharmacology by Bertram G. Katzung, Susen B. Masters and Anthony J. Trevor 12 th edition. Chapter 20- Drugs used in asthma by Dr. Homer A. Boushy, MD. Page no. 350

Ans. is 'd' i.e., Beta-2 receptor stimulation Proposed mechanisms of action of theophylline Phosphodiesterase inhibition (Non selective) Adenosine receptor antagonism (A1, A2) Increased histone Deacetylase activity (↑red efficacy of corticosteroids) Inhibition of intracellular calcium release Stimulation of catecholamine release Inhibition of NF - alpha Beta translocation into the nucleus (nuclear translocation) Mediator inhibition (Prostaglandins, TNF alpha)