Treatment of cough
Modified By :ISRAA
cough
• Cough is a useful physiological mechanism
that serves to clear the respiratory passages of
foreign material and excess secretions.
• It should not be suppressed indiscriminately.
• There are, however, many situations in which
cough does not serve any useful purpose but
may, instead only annoy the patient or
prevent rest and sleep.
Cough
• Chronic cough can contribute to fatigue,
especially in elderly patients, in such
situations the physicians should use a drug
that will reduce the frequency or intensity of
the coughing.
• Cough reflex is complex, involving the central
and peripheral nervous systems as well as the
smooth muscle of the bronchial tree.
Cough
• It has been suggested that irritation of the
bronchial mucosa causes bronchoconstriction,
which in turn, stimulates cough receptors ( which
probably represent a specialized type of stretch
receptor) located in the tracheobronchial
passages.
Types of cough
A) Acute cough =lasting<3 weeks
B) Chronic cough =lasing >8 weeks
Cough may be
i) Un productive (dry) cough OR
ii) Productive cough (sputum)
Most common causes of cough
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Common cold,
Upper/lower respiratory tract infection
Allergic rhinitis
Smoking
Chronic bronchitis
Pulmonary tuberculosis
Asthma
Gastroesophageal reflux
Pneumonia
Congestive heart failure
Bronchiectasis
Use of drugs (e.g., Angiotensin-converting enzyme inhibitors)
Treatment of Cough
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Antitussives (cough center suppressants)
Expectorants
Mucolytics
Antihistamines
Pharyngeal Demulcents
1) Antitussive
• Antitussive drugs act by ill defined effect in the
brain stem , depressing an even more poorly
defined “cough center”.
• All opioid narcotic analgesic have antitussive
narcotic analgesic in doses lower than those
required for pain relief
• They have minimum analgesic and addictive
properties
• Newer agent that only act peripherally on
sensory nerves in bronchi are being assessed
i) CODIENE
• It is the gold standard treatment for cough
suppression
• It decreases the sensitivity of cough center in the
CNS to peripheral stimuli, decrease the mucosal
secretion which thicken the sputum, and inhibit
ciliary activity
• These therapeutic effect occur at doses lower
than those required for analgesia but still incur
common side effect like constipation, dysphoria,
and fatigue, in addition to addiction potential
ii) DEXTROMETHORPHAN
• Is a synthetic derivative of morphine that
suppresses the response of the central cough
center
• It has no analgesic effect, has low addictive
profile, but may cause dysphoria at higher
doses
• Has significantly better side effect profile than
codeine and has been demonstrated to be
equally effective for cough suppression
2) Expectorants (Mucokinetics)
• Act peripherally
• Increase bronchial secretion
OR
• Decrease its viscosity and facilitates its
removal by coughing
• Loose cough ►less tiring &more productive
Classification of Expectorants
Classified into
a) Directly acting
E.g., Guaifenesin (glyceryl guaiacolate), Na+ &
K+ citrate or acetate,
b) Reflexly acting
E.g., Ammonium salt
Directly acting expectorants
i) Sodium & potassium citrate or Acetate
• They increase bronchial secretion by salt
action
ii) Guaifenesin
• Expectorant drug usually taken by mouth
• Available as single & also in combination
• MOA=Increase the volume & reduce the
viscosity of secretion in trachea & bronchi
Reflexly acting expectorants
• Ammonium salts
• Gastric irritants = reflex increase in bronchial
secretions + sweating
3) Mucolytics
• Help in expectoration by liquefy the viscous
tracheobronchial secretions
• E.g., Bromhexine, Acetyl cysteine,
i) Bromhexine
• Synthetic derivative of vasicine
MOA of Bromhexine
• a) Thinning & fragmentation of mucopolysaccaride
fibers
• b) ↑ volume & ↓ viscosity of sputum
3) Mucolytics
ii) Acetylcysteine
• Given directly into respiratory tract
• MOA of acetylcysteine: Opens disulfide bond in
mucoproteins of sputum =↓ viscosity
• Uses:
• Cystic fibrosis Onset of action quick---used 2-8
hourly
• Adverse effects:
• Nausea, vomiting, bronchospasm in bronchial
asthma
4) Antihistamines
• Added to antitussives/expectorant formulation
• Due to sedative anticholinergic actions produce
relief from cough but lack selectivity for cough
center
• No expectorant action =▼secretions
(anticholinergic effect)
• Suitable for allergic cough
• E.g., Chlorpheniramine and diphenhydramine
5) Pharyngeal demulcents
• Soothe the throat (directly & also by promoting
salivation
• Reduces afferent impulses from inflamed/irritated
pharyngeal mucosa
• Provide symptomatic relief in dry cough arising
from throat
• E.g. lozenges, cough drops, glycerine, liquorice,
honey
Good luck