management of cough

1. COUGH

2. Introduction:
a protective reflex meant for expulsion of respiratory secretions or
foreign particles from air passages
due to stimulation of:
• mechano- or chemoreceptors in throat/ respiratory passages or
• stretch receptors in the lungs
Two types:
• Useless cough(non productive)
• Useful cough(productive)

3. Classification of drugs:
1. Pharyngeal demulcents:
Lozenges, cough drops, linctuses containing syrup, glycerine, liquorice.
2. Expectorants (Mucokinetics):
(a) Bronchial secretion enhancers:
Sodium or Potassium citrate, Potassium iodide, Guaiphenesin
(Glyceryl guaiacolate), balsum of Tolu, Vasaka, Ammonium chloride.
(b) Mucolytics:
Bromhexine, Ambroxol, Acetyl cysteine, Carbocisteine

4. 3. Antitussives (Cough centre suppressants):
(a) Opioids:
Codeine, Ethylmorphine, Pholcodeine.
(b) Nonopioids:
Noscapine, Dextromethorphan, Chlophedianol.
(c) Antihistamines:
Chlorpheniramine, Diphenhydramine, Promethazine.
(d) Peripherally acting:
Prenoxdiazine.
4. Adjuvant antitussives:
Bronchodilators: Salbutamol, Terbutalin.

5. DEMULCENTS AND EXPECTORANTS:
Demulcents: Sooth the throat and reduce afferent impulses from
pharyngeal mucosa
Expectorants (Mucokinetics) : increase bronchial secretion or reduce
its viscosity
 Sodium and potassium citrate: increase bronchial secretion by salt
action
 Potassium iodide: irritate the airway mucosa(can affect thyroid
function)

6.  Guaiphenesin, vasaka, tolu balsum:
 Plant products
 Enhance bronchial secretion
 Increase mucociliary function
 Ammonium salts: reflexly increase respiratory secretions
US-FDA has stopped marketing of all expectorants, except
guaiphenesin
Steam inhalation and proper hydration may be more helpful in
clearing airway mucus

7. MUCOLYTICS:
Bromhexine:
derivative of Adhatoda vasica (Vasaka)
depolymerises mucopolysaccharides directly as well as by liberating
lysosomal enzymes
useful if mucus plugs are present
Side effects:
rhinorrhoea and lacrimation, nausea, gastric irritation, hypersensitivity

8. Ambroxol:
metabolite of bromhexine
Acetylcysteine:
opens disulfide bonds in mucoproteins present in sputum
has to be administered directly into the respiratory tract
Carbocisteine:
MOA similar to acetylcysteine
Administered orally(250–750 mg TDS)
may break gastric mucosal barrier : contraindicated in peptic ulcer
patients

9. ANTITUSSIVES:
MOA:
• act in the CNS to raise the threshold of cough centre or
• act peripherally in the respiratory tract to reduce tussal impulses
• or both
Used in:
• dry nonproductive cough
• cough is unduly tiring, disturbs sleep or
• Is hazardous(hernia, piles, cardiac disease, ocular surgery)

10. Opioids:
Codeine:
Qualitatively similar to and less potent than morphine
more selective for cough centre
Suppresses cough for about 6 hours(standard antitussive)
Antagonised by naloxone
Abuse liability is low(still present)
Side effect:
Constipation(m/c), respiratory depression and drowsiness

11. Ethylmorphine:
similar & less constipating than codein
Pholcodeine:
no analgesic or addicting property
similar in efficacy to codeine
Longer acting

12. NONOPIOIDS:
Noscapine (Narcotine):
An opium alkaloid of the benzoisoquinoline series
no narcotic, analgesic or dependence inducing properties
nearly equipotent to codeine
useful in spasmodic cough
can release histamine and produce bronchoconstriction in asthmatics
Side effects:
Headache and nausea

13. Dextromethorphan:
synthetic central NMDA (N-methyl D-aspartate) receptor antagonist
d-isomer is antitussive while l-isomer is analgesic
does not depress mucociliary function
devoid of constipating action
Antitussive action: equivalent to codein
Side effect:
 Dizziness, nausea, drowsiness.
 hallucinations and ataxia at high doses

14. ANTIHISTAMINES:
Used for sedative and anticholinergic action
Not selective for cough centre
May reduce secreations
Useful for cough in respiratory allergic states
Commonly used drugs:
 Chlorpheniramine (2–5 mg),
 Diphenhydramine(15–25 mg)
 Promethazine (15–25 mg

15. PERIPHERALLY ACTING ANTITUSSIVES:
Prenoxdiazine:
desensitizes the pulmonary stretch receptors and reduces tussal
impulses originating in the lungs
indicated in cough of bronchial origin
Efficacy is not good enough

16. BRONCHODILATORS:
Bronchospasm can induce or aggravate cough
Pulmonary receptors stimulation(in bronchial hyperactivity) can
trigger both
Cough &
Bronchoconstriction
Bronchodilators improve the velocity of airflow during coughing