ANTITUSSIVES
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.
 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.
TWO TYPES OF COUGH
 Productive
 leads to removal of sputum from the lungs
 Dry cough
 no removal of sputum
COUGH REFLEX
 Has both sensory (afferent) and motor (efferent) pathways
 The internal laryngeal nerve, a branch of the superior
laryngeal nerve (CN X), carries the sensory information
away from the area above the glottis in the larynx to the CNS
via cranial nerve X (vagus). Stimulation of this area by dust
or other foreign particles produces a cough, which is
necessary to remove the foreign material from the
respiratory tract before it reaches the lungs.
 The mechanism of a cough is as follows:
o Diaphragm (innervated by phrenic nerve) and external
intercostal muscles (innervated by segmental
intercostal nerves) contract, increasing the volume of
the lungs and making the pressure of air within the
lungs lower than atmospheric pressure.
o Air rushes into the lungs in order to equalise the
pressure.
o The glottis closes (muscles innervated by recurrent
laryngeal nerve) to prevent air escaping while the
diaphragm relaxes and expiratory muscles contract.
This reduces the volume of the lungs, therefore
increasing pressure.
o The pressure of air within the lungs is now greater than
atmospheric pressure and so air is trying to escape.
o Glottis opens, releasing air at over 100 mph.
COUGH
 TREATMENT
 mainly consists of treating the underlying cause
 productive cough should NOT be suppressed
o because sputum needs to be cleared
o EXCEPT in special circumstances (e.g., when it
TYPES OF COUGH
 Acute cough =lasting<3 weeks
 Chronic cough =lasing >8 weeks
 Cough may be
 i) Un productive (dry) cough OR
 ii) Productive cough (sputum)
CLASSIFICATION OF DRUGS USED FOR NON SPECIFIC
TREATMENT OF COUGH
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Cough suppressants
Centrally acting Antitussives
Peripheral Antitussives
Cough expectorants
Antihistamines
Bronchodilators
COUGH SUPPRESSANTS (Anti-tussives)
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Centrally acting Antitussives
Narcotic antitussive
Opiates
Codeine
Pholcodine
Hydrocodone
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Non narcotic antitussives
Opiates
Dextromethorphan
Levopropozyphene
Noscapine
NON-OPIATES
 Diphenhydramine
 Benzonatate
PERIPHERAL ANTITUSSIVES
o
o
o
o
o
o
o
o
o
o
o
Demulcents
Linctus
Lozenges
Liquorice
Inhalation
Water aerosol inhalation
Benzoin
Menthol
Local anaesthetics
Benzonatate
Lignocaine (only in special circumstances)
2) COUGH EXPECTORANTS
1 Drugs acting Reflexly
 Ipecacuanha
 Ammonium chloride
 Potassium Iodide
2 Drugs Acting Directly
 Potassium Iodide
 Guaiphenesin
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Mucolytics
Acetylcysteine
Bromhexine (Bisolvon)
Carbocisteine
Methylcysteine
MUCOLYTIC
 A mucolytic is a drug that breaks down thick mucus, making
it thinner and easier to cough out.
EXPECTORANT
 An expectorant is a drug which makes the cough more
productive by loosening and liquefying bronchial secretions.
 Also known as Mucokinetics
ANTITUSSIVES
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o Antitussives are substances that specifically inhibit or
suppress the action of cough
Depression of medullary centre or associated higher centers.
Increases threshold of the cough centre.
Interruption of tussal impulses peripherally in the respiratory
tract.
Inhibition of conduction along the motor pathways.
ANTIHISTAMINES
 Chlorphenaramine 2-5mg
 Diphenhydramine 5-25mg
 Promethazine
15-25mg
 Anti histamines provides relief in cough due to sedative and
anticholinergic action.
 They lack selectivity for cough centres
 They have been promoted for treatment of cough in allergic
states.
 No efficacy in Asthma
BRONCHODILATORS
 Bronchodilators by clearing secretions through increase in
surface velocity of airflow during cough relieves .
 Should be used only when element of bronchoconstriction is
present and not routinely
 Fixed dose combination of bronchodilators with anti tussives
not preferred .
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