This document discusses drugs used for cough. It begins by defining cough and describing the cough reflex and mechanism. It then distinguishes between productive and non-productive cough. The causes or etiologies of cough are outlined. The document then describes different classes of drugs used for cough, including demulcents, expectorants, mucolytics, and antitussives. Specific drugs from each class are provided as examples, along with their mechanisms of action and indications. The document emphasizes that cough remedies should be prescribed rationally.

1. DRUGS FOR COUGH
Dr. D. K. Brahma
Associate Professor
Department of Pharmacology
NEIGRIHMS, Shillong

2. WHAT IS COUGH ?
 It’s a protective reflex – for expulsion of
respiratory secretions and foreign
particles from air passages
Respiratory secretions ! – URT - LRT
 Stimulation of mechano or chemoreceptor
– throat, respiratory passages and stretch
receptors in the lungs
 Afferent fibres in vagus & sympathetic -
impulses to cough center – medulla
 Cough Mechanism !

3. COUGH – TYPES AND MERITS
 Non-productive (Dry Cough) and Productive
 Nonproductive ones need suppression –
cerebral hypoxia, rupture of bullas and fracture
ribs etc.
 Productive – needs to clear airway
 May be harmful if suppressed !
 Amount of product Vs effort of coughing
 Most of the time, coughing is beneficial
 Removes excessive secretions
 Removes potentially harmful foreign substances
 In some situations, coughing can be harmful, such as
after hernia repair surgery

4. COUGH ETIOLOGY
1. Upper/Lower Respiratory Tract Infection
2. Postnasal drip due to sinusitis, rhinitis
3. Smoking/Chronic Bronchitis
4. Pulmonary Tuberculosis
5. Asthmatic cough
6. Gastrointestinal reflux
7. Drugs – Captopril and Iodides ……

5. COUGH – DRUGS (NONSPECIFIC)
1. PHARYNGEAL DEMULCENTS: Lozenges, cough
drops, linctuses glycerine and liquorice
2. EXPECTORANTS: (MUCOKINETICS – secretion
enhances):
a) Secretion Enhancers: Sodium and Potassium citrate, KI,
Guaiphenesin (Glyceryl guaicolate), Vasaka, Ammonium
chloride
b) Mucolytics: Bromhexine, Ambroxol, Acetylcysteine,
Carbocysteine
3. CENTRAL COUGH SUPPRESSANTS:
a) Opioids: Codeine, Pholcodeine
b) Nonopioids: Noscapine, Dextromethorphan
c) Antihistamines: Chlorpheniramine maleate,
Diphenhydramine,promethazine
4. ADJUVANT: Salbutamol, Terbutaline

6. DRUGS OF COUGH – DEMULCENTS
AND EXPECTORANTS
 Demulcents
 Soothing effect and symptomatic relief – reduce
afferent impulses - act by increasing flow of saliva
 Expectorants (Mucokinetics)
1. Increase Bronchial Secretion – Na and K citrate
2. Irritation of Bronchial mucosa – Iodides
3. Enhance Bronchial secretions (and mucociliary
functions) – Guaiphenesin, Vasaka
4. Ammonium salts – nauseating, reflex stimulation
of bronchial secretion

7. ACTIONS OF DRUGS OF COUGH –
MUCOLYTICS
Bromhexine: Derivative of Adhatoda vasica
(Vasaka) – increases bronchial secretion
 Depolymerises mucopolysaccharides in bronchial
secretions – directly or by liberating lysosomal
enzyme
 Fibres of sputum breaks down
 Useful in mucus plug
Ambroxol: Similar to Bromhexine
Acetylcysteine: Breaks sulfide bond in
mucopolysaccharides of bronchial secretions –
Respiratory tract administration
Carbocysteine: Similar to acetylcysteine –
administered orally

8. ACTIONS OF DRUGS OF COUGH -
ANTITUSSIVES
 Action via CNS
 Act by raising the threshold of cough centres
 Also periphery – by reducing cough impulse
 Uses:
 dry and nonproductive cough
 Unusually tiring cough, disturbed sleep or hazardous
– hernia, piles, cardiac diseasead oculr surgery

9. ANTITUSSIVE - CODEINE
 Opioid – opium alkaloid – methyl morphine
 Partly converts to Morphine
 Less potent than Morphine and degree of
analgesia is equivalent to Aspirin (60 mg)
 But, more selective for cough centers and action
lasts for 6 Hours
 Blocked by Naloxone
 Low abuse liability
 Drawbacks: constipation, respiratory
depression and drowsiness (Higher doses)
 PHOLCODEINE: No analgesia or addicting
property – longer acting

10. COUGH DRUGS - NONOPIOIDS
 Noscapine: Opium alakaloid
 Depresses cough, but no analgesic, narcotic or
dependence liability
 Equipotent with codeine – spasmodic cough
 Histamine release – no in asthma
 Dextromethorphan:
 Synthetic – d-isomer (antitussive) and l-isomer
(analgesic)
 Effective as codeine but no addicting and constipating
effect – No impairment of mucocilliary function
 But, dissociative effect – recreational drug?
 In Combination – Paracetamol (acetaminophen)

11. COUGH DRUGS
 Antihistamine:
Chlorpheniramine, Diphenhydramine and
Promethazine
MOA: Sedative and anticholinergic
Useful in allergic cough
 Bronchodilators:
Bronchospasm can induce cough and
constriction
Hyperactivity of Bronchial smooth muscles
Bronchodilators – relieves cough and improves
clearance during cough

12. THANK YOU/KHUBLEI SHIBUN
Cough syrups, remedies for cough and cold are
FREELY AVAILABLE
however, needs rational prescribing