This document discusses drugs for cough. It begins by describing the mechanism and causes of cough. Cough can be voluntary or reflexive, and has afferent and efferent pathways involving various nerves. Causes include upper respiratory infections, pneumonia, and other conditions. The document then classifies drugs for cough into four main categories: pharyngeal demulcents to soothe the throat; expectorants to increase or thin mucus; antitussives to suppress coughing; and bronchodilators to relieve cough caused by bronchospasm. Specific drugs and combinations are provided as examples for each category. The document concludes by describing specific treatments for cough based on its underlying cause.

1. DRUGS FOR COUGH
Dr.Vijay Bhushanam

2. Cough (Introduction)
• Cough is an explosive expiration, that provides a normal
protective mechanism for clearing the tracheo-bronchial
tree of secretions and foreign material.
• When excessive or bothersome, it is also one of the most
common symptoms for which patients seek medical
attention.
• Reasons for this include discomfort from the cough itself,
interference with normal lifestyle, and concern for the
cause of the cough, especially fear of cancer.

3. Mechanism of cough
• Coughing may be initiated either voluntarily or reflexively.
• As a defensive reflex it has both afferent and efferent
pathways.
• The afferent limb includes receptors within the sensory
distribution of the trigeminal, glossopharyngeal, superior
laryngeal and vagus nerves.
• The efferent limb includes the recurrent laryngeal nerve
and the spinal nerves.

4. Mechanism of cough (Cont.)
• Deep inspiration glottic closure  relaxation of the
diaphragm  muscle contraction against a closed glottis
 markedly positive intrathoracic pressure narrowing
of the trachea  glottis opens at once  the large
pressure differential between the airways and the
atmosphere coupled with tracheal narrowing produces
rapid flow rates through the trachea COUGH
• The shearing forces that develop aid in the elimination of
mucus and foreign materials.

5. Etiology of Cough
• The most common causes of cough can be categorized
according to the duration of the cough.
• Acute cough (<3 weeks): URTIs (especially the common
cold, acute bacterial sinusitis, and pertussis), pneumonia,
pulmonary embolus, and congestive heart failure.
• Sub-acute cough (3-8 weeks): post-infectious
• Chronic cough (>8 weeks):
In a smoker: chronic obstructive lung disease or
bronchogenic carcinoma.
In a nonsmoker: postnasal drip (sometimes
termed the upper airway cough syndrome), asthma, and
gastroesophageal reflux.

6. Types of Cough
• Non-productive (dry): No useful purpose, increases
discomfort to the patient  needs suppression
• Productive (tenacious): Presence of excessive
sputum  suppression not desired  needs
coughing/clearing out of the sputum

7. Classification of drugs for Cough
•
•
•
•
Pharyngeal demulcents: Lozenges, cough drops, linctuses
containing syrup, Glycerine, Liquorice
Expectorants:
1. Mucokinetics (Bronchial secretion enhancers): Sodium or
potassium citrate, Potassium iodide, Guaphenisin (Glyeryl
guaiacolate), balsum of Tolu, Vasaka, Ammonium chloride.
2. Mucolytics: Bromhexene, Ambroxol, Acetylcystein,
Carbocystein
Antitussives (Cough center supressants):
a) Opioids: Codein, Pholcodein
b) Non-opioids: Noscapine, Dextromethorphan, Chlophedianol
c) Antihistaminics:Chlorpheniramine, Diphenhydramine,
Promethazine
Adjuvant antitussives:
Bronchodilators: Salbutamol, Terbutaline

8. Pharyngeal demulcents
• Sooth the throat and reduce afferent impulses from the
inflamed/irritated pharyngeal mucosa.
• E.g: Lozenges, cough drops, linctuses containing syrup,
Glycerine, Liquorice

9. Expectorants
• Increase bronchial secretions or reduce its viscosity,
facilitating its removal by coughing
• E.g:
• Mucokinetics (Bronchial secretion enhancers): Sodium or
potassium citrate, Potassium iodide, Guaphenisin (Glyeryl
guaiacolate), balsum of Tolu, Vasaka, Ammonium
chloride.
• Mucolytics: Bromhexene, Ambroxol, Acetylcystein,
Carbocystein

10. Antitussives
(Cough center supressants)
• These act
– in CNS to raise the threshold of cough center (and/or)
– peripherally in Respiratory tract to reduce tussal impulse
• Should be used only for dry unproductive cough (or)
• if the cough is unduly tiring, disturbs sleep (or)
• is hazardous (hernia, piles, cardiac ds., ocular surgery etc)
• E.g:
• Opioids: Codein, Pholcodein
• Non-opioids: Noscapine, Dextromethorphan,
Chlophedianol
• Antihistaminics: Chlorpheniramine, Diphenhydramine,
Promethazine

11. Bronchodilators
• Bronchospasm can induce/aggravate cough, especially
in individuals with bronchial hyperreactivity
• Bronchodilators relieve cough in such individuals
• Improve the effectiveness of cough in clearing
secretions by increasing the surface velocity of airflow
during cough
• E.g: Salbutamol, Terbutalin

12. Antitussive/Expectorant
Combinations
• AMBRODYL PLUS: Ambroxol, Chlorpheniramine,
Salbutamol, Guaphenesin.
• ASTHALIN: Salbutamol, Guaphenesin.
• ASCORIL-C: Codeine, Chlorpheniramine.
• BENADRYL: Diphenhydramine, Ammonium chloride,
Sodium citrate, Menthol.
• GRILINCTUS: Dextromethorphan, Chlorpheniramine,
Guaphenesin, ammonium chloride.

13. Specific Rx for cough
• URTI/LRTI  Appropriate antibiotics
• Smoking/Chr. Bronchitis  Cessation of smoking/
avoidance of pollutants
• PTB ATT
• Post nasal drip due to sinusitis Antibiotics/Nasal
decongestants/H1 antihistaminics
• Postnasal drip due to allergy Avoidance of precipitating
factors/Corticosteroid nasal spray/H1 antihistaminics
• GERD H2 blockers/PPIs/Cisapride
• ACE inhibitor induced cough  Switch to ARBs/CCBs
• Asthmatic cough Inhaled β2
agonists/Ipratropium/Corticosteroids

14. THANK
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