Cough pharamacology Flashcards
How does opioid drugs work in Cough ?
They increase the AP threshold of the medullary cough centre neurons and thereby reduce cough reflex activation. They are most effective for cough arising from the lower airways.
What are the opioid drugs indicated for cough ?
*Codeine is the most commonly used drug.
* In terminal cough morphine.
* NMDA receptor antagonist Dextromethorphan is an opioid analogue indicated for the treatment of cough as they do not have any analgesic or sedative effect.
What are the peripherally acting anti-tussives ?
- lidocaine- As an oropharyngeal spray to reduce the cough and gag reflexes during bronchoscopy.
- Antihistamines- reduce postnasal drip from allergic rhinitis, they have no anti-tussive effect.
What are the local acting cough medicines ?
Demulcents contained in Many cough lozenges act on the upper airway above the larynx and reducing local irritation which trigger cough reflex.
What is the action of Expectorants such as guaifenesin ?
They are thought to make the cough more effective by increasing the volume of mucus secretion. There is no evidence that they have any clinical value.
How does mucolytics such as erdosteine and carbocisteine work ?
- They reduce the viscosity of bronchial secretions by breaking disulfide crosslinks between mucin monomers, but no evidence that they have any expectorant effects
- In COPD and bronchiectasis their effects are more related to their antioxidant properties in scavenging reactive oxygen species.
How does recombinant human deoxyribonuclease I: Dornase alfa work ?
In cystic fibrosis the the mucus secretion has little mucin, it is a compound of polymeric network of DNA from degraded inflammatory cells and F-actin. Dornase alfa is an enzyme that digest extracellular DNA and reduce the viscosity of mucus in cystic fibrosis.
What is the action of nebulized Hypertonic sodium chloride ( 5 to 7%) work?
*It reduces sputum viscosity by increasing Na + concentration in the airway surface liquid, which draws water into the airway. In addition, it disrupts ionic bonds in the mucus gel, which may reduce cross-linking and entanglement.
* It is indicated in cystic fibrosis, bronchiectasis, and in critically ill people receiving invasive mechanical ventilation.
What is the treatment of self limiting nonproductive acute cough seen in viral illness ?
- simple linctus or a weak opioid given for a maximum of 5 days.
- codeine is contraindicated in children <12 and sedative anti-histamine containing preparations are contraindicated in children <6.
What is the indication for treatment in acute cough ?
It only should be treated if it is unproductive or excessive.
What should be the approach in ACE inhibitor related cough ?
- A trial of ARB instead of ACEI should be considered before treating or investigating cough in these patients.
How to treat Chronic nonproductive cough in terminal lung cancer?
Strong opioid such as Morphine.
What is the indication of Acetazolamide?
It is a carbonic anhydrase inhibitor that stimulates the respiratory centre by creating a mild metabolic acidosis. It is indicated for the prevention and management of acute altitude sickness.
