This document discusses the pharmacotherapy of cough. It begins by defining cough and describing the cough reflex mechanism. Common causes of cough are then listed, including respiratory infections, allergies, smoking, and others. Drugs are classified as antitussives to suppress cough, expectorants to increase mucus secretion, and mucolytics to reduce mucus viscosity. Specific antitussives discussed include codeine, pholcodeine, noscapine, and dextromethorphan. Expectorants include guaiphenesin and potassium iodide. Mucolytics include acetylcysteine, carbocysteine, bromhexine, and ambroxol. Other treatment modalities involve hydration

1. Pharmacotherapy of Cough
Dr YASHASWINI P
DEPT OF PHARMACOLOGY

2. Learning objectives
Cough
Definition
Types
C0ugh reflex
Common causes
Classification of drugs
Individual drugs
Other treatment modalities
Mode of approach

3. Cough
 Protective reflex mechanism which removes foreign material
and excess respiratory secretion
Involuntary reflex and major defensive mechanism

 Disturb patient ,its rest and sleep

4.  Mechanism of Cough is complex
 Central and peripheral nervous systems involved
 Changes in Bronchial smooth muscle and bronchial mucosa
Is responsible
 Cough centre-Medulla
 Cough receptor-stretch receptor-pharynx,Larynx,Lungs
Mechanism of cough

5. The cough reflex.

6. Types of cough
Productive cough
Non-productive/Dry cough

7. Common causes of cough
 Upper/lower respiratory tract infection
 Allergic rhinitis
 Smoking
 Chronic bronchitis
 Pulmonary tuberculosis
 Asthma
 Gastro esophageal reflux
 Pneumonia
 Congestive heart failure
 Bronchiectasis
 Use of drugs ( ACE inhibitors)

8. Drugs which induce cough
ACE inhibitors
Amiodarone
Iodide
Beta blocker

9. CLASSIFICATION
Anti tussive – Cough suppressant ( tussis-cough)
Expectorants-Increase volume of mucus secretion
Mucolytic- Reduce viscosity of mucus
Mucokinetic-Increase mobility of cough

10. Classification of Drugs for cough
1.Antitussives
Centrally acting
Opioid mechanism (Codeine,pholcodeine)
Non opioid mechanism (Noscapine,dextromethorphan)
Peripherally acting
Pharyngeal demulcent
Syrup, lozenges
Steam inhalation

11. 2.Expectorants
Secretion enhancers
Guaiphensin, sodium citrate, potassium
citrate, potassium iodide
3.Mucolytic
Bromhexine,ambroxol,acetylcysteine,methyl cysteine
4. Others
Antihistamine,Bronchodilators,Local anesthetic

12. Antitussives
Ideally cough should not be suppressed
Treatment of underlying cause


 Drugs which suppress cough-Antitussives
M.O.A
Raise threshold & inhibit cough reflex in
cough centre in medulla
In respiratory tract reduce tussal impulse


 Useful for dry cough

13.  Semi synthetic opioid analgesic
 Less potent than morphine
 More selective for cough centre
 Low dose (10 mg BD), 6hours
 Anti tussive action –blocked by Naloxone
 Has less addiction
S/E
 Constipation ,Drowsiness, Respiratory depression
 Contraindicated in bronchial asthma
Codeine

14. Pholcodeine
 Antitussive efficacy similar to codeine
 No analgesic/addictive effect
 Longer acting
 Dose 10-15mg 12 hours

15. Noscapine
Opium alkaloids belongs to benzyl isoquinoline group
No addictive, analgesic & constipating properties
Do not interfere with mucocilliarymovement
Different mechanism
Release histamine, bronchoconstriction
S/E
 Nausea, headache, tremor
Dose 15 mg

16. Dextromethorphan
D-isomer of methorphan
Raise threshold for cough centre
Antitussive action not blocked by Naloxone
M.O.A
NMDA receptor antagonist
Least addiction and constipation, Minimal drowsiness
No analgesic action, No affect on mucocilliaryaction
Uses
Use along with antihistamine and bronchodilator as suppressant
S/E
Nausea, vomiting, ataxia
Dose- 10mg TDS

17. Pharyngeal demulcents
Sooth throat
Reduce afferent impulse from inflamed pharyngeal mucosa
Symptomatic relief in dry cough
Syrup, Lozenges

18. Q.A young patient is diagnosed with asthma. His primary
symptom is frequent cough ,not bronchospasm and
wheezing.Ashthma medication started but until their
effect develop we want to suppress the cough without
running risk of suppressing ventilatory drive or causing
sedation. Which is the best drug for this?
A.Codeine
B.Dexomethorphan
C.Promethazine
D.None of the above

19. Expectorants
↑Bronchial secretion,↓Viscoscity
Facilitates removal

20. Sodium & potassium citrate or Acetate
M.O.A
 Bronchial secretion by salt action
Guaiphenesin
 Expectorant drug usually taken by mouth
M.O.A


Increase airway secretion and mucocilliary activity
Dose 100-200mg BD
Ammonium chloride,Ipecac


Reflexly increase respiratory secretion
Gastric irritant

21. Potassium Iodide
 Direct
 Indirect
 Liquefaction of tenacious sputum
A/E
 Metallic taste, Swelling of salivary and lacrimal gland
 Hypothyroidism
 Dose-300mg TDS

22. Mucolytics
Acetyl cysteine
M.O.A
 Reduce viscosity of sputum by opening disulfide bond of
mucoprotein
S/E
Nausea,vomiting,stomatitis,bronchospasm,rhinorrhea
Dose 200mg


 Administer directly to respiratory tract

23. Carbocysteine
Liquefies viscid sputum

S/E
G.I irritation, peptic ulcer

 Dose 250-750mg TDS

24. Bromhexine
 Synthetic derivative of vasicine (Vasaka)
M.O.A
Depolymerization of muco polysaccharide
Increasing lysosomal enzyme activity
↑ volume & ↓ viscosity of sputum



S/E
 GIT upset, rhinorrhea,lacrimation
Uses
Useful where mucus plug present(tracheostomy,emphysema,CF)
Dose 30mg TDS

25. Ambroxol
 Metabolite of bromhexine
 Similar properties
 Dose 15-30 mg TD

26. Q.Which of the following statements regarding opiate action
is correct?
A. Trigger vagal reflex to suppress cough
B.Cause diarrhea
C.Stimulate production of cough
D.Suppress cough centre

27. Q.Which is NOT a mucolytic?
A.Ambroxol
B.Acetylcysteine
C.Bromhexine
D.Potassium iodide

28. Antihistamines
Added to antitussives/expectorant formulation
Relief in cough due to sedative & anticholinergic actions
Lack selectivity for cough centre
No expectorantaction
↓Secretions (anticholinergic effect)
Suitable for allergic cough but not for asthma
Ex.Chlorpheniramine, diphenhydramine, promethazine

29. Bronchodilators
M.O.A
↑Surface velocity of air flow during cough
 Clear secretions of airway
Not used routinely for every type ofcough
present ( Bronchial
 Use only when bronchoconstriction is
asthma)
Ex. β2-agonist (salbutamol, terbutaline)

30. Role of hydration in cough
Dehydration increase viscosity of secretion
Adequate fluid –decrease viscosity
Highly effective
Role of steam inhalation
Useful for liquefaction of tenacious sputum
Role of other agents

31. Summary
Cough-protective reflex
Treat underlying cause
Provides symptomatic treatment
Antitussive –Suppress cough centre
Opioid&non opiod
Mucolytic-Lysis
Mucokinetic –Facilitates expulsion
Adjuvants-Anti-histamine,Bronchodilator

32. Thank you