2. TREATMENT OF 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.
3. TREATMENT OF 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.
4. TREATMENT OF 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.
5. TREATMENT OF COUGH
• Afferent conduction from
these receptors is via
fibers in the vagus nerve;
central components of the
reflex probably involve
several mechanisms or
centres that are distinct
from the mechanisms
involved in the regulation
of respiration.
6. TREATMENT OF COUGH
• The drugs that directly or indirectly can affect this complex mechanism are
diverse
• For example , cough may be the first or only symptom in bronchial asthma or
allergy, and in such cases bronchodilators(e.g., 2 – adrenergic receptor
agonists have been shown to reduce cough without having any significant
central effects, other drugs act primarily on the central or the peripheral
nervous system components of the cough reflex.
7. TREATMENT OF COUGH
What is a cough?
• Forceful release of air from lungs
• Sudden, often involuntary (protective)
reflex and major defensive mechanism
Causes of Cough
• Expulsion of respiratory secretion or
foreign particles or irritant or excessive
mucus from air passages
• Symptom of an underlying respiratory
and/or cardiovascular pathology.
8. Mechanism of cough
Stimulation of mechano-or chemoreceptors (throat, respiratory passages
or stretch receptors in lungs)
Afferent impulses to cough centre (medulla)
Efferent impulses via parasympathetic & motor nerves to diaphragm, intercostal
muscles & lung
Increased contraction of diaghramatic, abdominal & intercostal (ribs) muscles
noisy expiration (cough)
9. Types
of
Cough Duration
Acute < 3 weeks
Subacute/Prolonged 3-8 weeks
Chronic > 8 weeks
Nature Productive Wet with sputum
Nonproductive Dry with no sputum
Cause
Spesific
Nonspesific
Refractory Persist after therapy
Recurrent Cough
≥ 2 episode /year each
lasting >7-14 days
11. Treatment of Cough
Antitussives (cough centre suppressants)
Expectorants (Mucokinetics)
Mucolytics
Antihistamines
Bronchodilators
Pharyngeal Demulcents
12. Antitussives (cough centre suppressants)
Mechanism of Action
Mainly suppress cough centre
in medulla (both central &
peripheral effects)
E.g., Opoid drugs (codeine,
pholcodeine, noscapine,
dextromethorphan)
Opioid = most effective for
cough
Drugs suppress cough & produces symptomatic relief
13. Codeine
Codeine= prodrug
metabolized to
morphine
It is an alkaloid
found in Opium
poppy plant
Has less addiction +
Respiratory centre
depressant ↓
Has useful
antitussive action at
low doses (<15 mg)
Produce drowsiness,
thickening of
sputum &
constipation
14. Noscapine & Pholcodeine
Related to papaverine
Do not have addictive, analgesic & constipating properties
Do not interfere with mucocilliary movement
Noscapine (15 mg) & pholcodeine (10 mg)=syrup
15. Dextromethorphan
Available in syrup, tablets, spray forms
Mecahnism of Action
• NMDA receptor antagonist
Uses
• Cough suppressant, temporary relief of cough caused by
minor throat & bronchial irritation (accompanies with flu &
cold), pain relief
Adverse Effects
• Nausea, vomiting, drowsiness, dizziness, blurred vision
16. Expectorants (Mucokinetics)
• Increase bronchial secretion
• Decrease its viscosity facilitates its removal by coughing
• Loose cough ►less tiring & more productive
Act peripherally
• Directly acting
• E.g., Guaifenesin (glyceryl guaiacolate), Na+ & K+ citrate or
acetate,
• Reflexly acting
• E.g., Ammonium salt
Classified into
17. Antitussive Agents
Sodium & potassium citrate
or Acetate
• They act directly
• Actions:
• ▲Bronchial secretion by
salt action
Guaifenesin
• Expectorant drug usually
taken by mouth
• Available as single & also
in combination
• Mechanism of action
• Increase the volume &
reduce the viscosity of
secretion in trachea &
bronchi
19. Mucolytics
Help in expectoration by liquefy the viscous
tracheobronchial secretions
• Bromhexine, Acetyl cysteine,
Bromhexine
• Synthetic derivative of vasicine (alkaloid= Adhatoda vasica)
• Thinning & fragmentation of mucopolysaccaride fibers
• ↑ volume & ↓ viscosity of sputum
20. N-acetylcysteine
Opens disulfide bond in mucoproteins of sputum =↓ viscosity
• Cystic fibrosis (to viscosity of sputum)
• Onset of action quick---used 2-8 hourly
Uses
• Nausea, vomiting, bronchospasm in bronchial asthma
Adverse effects
21. Antihistamines
Added to antitussives/expectorant formulation
Due to sedative & anticholinergic actions produce relief in cough but lack
selectivity for cough centre
No expectorant action =▼secretions (anticholinergic effect)
Suitable for allergic cough (not for asthma)
E.g., Chlorpheniramine, diphenhydramine, promethazine
22. Bronchodilators
Bronchospasm or stimulation of
pulmonary receptors = induce or
aggravate cough + bronchoconstriction
e.g. β2-agonist (salbutamol, terbutaline)
Mechanism of action of
bronchodilators in cough
▲surface velocity of air flow during
cough→ Clear secretions of airway
Not used routinely for every type of
cough but only when bronchoconstriction
is present
23. Pharyngeal demulcents
Soothe the throat (directly & also by promoting
salivation)
▼ afferent impulses from inflamed/irritated
pharyngeal mucosa
Provide symptomatic relief in dry cough arising
from throat
• E.g. lozenges, cough drops, glycerine, liquorice, honey
24. Specific treatment approach to cough
Etiology of cough
Upper/lower respiratory
Smoking/chronic bronchitis
Pulmonary tuberculosis
Asthmatic cough
Postnasal drip (sinusitis)
Treatment
Appropriate antibiotics
Cessation of smoking
Antibiotics
Inhaled β2 agonists, ipratropium
corticosteroid
Antibiotics, nasal decongestants,
antihistamines
