This document outlines drugs used to treat respiratory system diseases. It discusses expectorants which increase mucus secretion and enhance expulsion, helping to clear airways. Respiratory stimulants act centrally to increase breathing rate and relax bronchi. Antitussives suppress cough through depressing the cough center. Bronchodilators relax smooth airway muscles to relieve symptoms. Membrane shrinking drugs include decongestants, corticosteroids, NSAIDs and antihistamines which help reduce inflammation. The mechanisms, indications, and side effects of these commonly used respiratory drugs are presented.

1. DRUGS ACTING ON RESPIRATORY SYSTEM

2. CONTENT OUTLINE
• Parts of Respiratory System
• Diseases of respiratory System
• Principles of RT system diseases
• Commonly Used Drugs
• Their MOA & Indications

3. PARTS OF RT SYSTEM

4. DISEASES OF RT SYSTEM
 Cough
 Asthma
 Bronchitis
 COPD
 Cystic Fibrosis
 Pneumonia
 Tuberculosis
 Pulmonary Emphysema
 Pasteurellosis etc.

5. PRINCIPLES…..
 Early Stage
Dry harsh, painful & entirely useless cough
TREATMENT:
i. To increase mucous Secretion
ii. Reduce frequency of cough
iii. Prevent stimulation on mucosa by coating the
mucosa
iv. Centrally depressing cough center

6. CONTD..
 Recovery Stage
Excess mucus & Tissue debris in airways
Prevent the free air passage & stimulate coughing
TREATMENT:
i. To increase the fluidity of mucus
ii. Stimulate the activity of cilia thus all debris
expelled by coughing

7. e
Expectorants
Respiratory
stimulants
Antitussive Bronchodilator
COMMONLY USED DRUGS…
Membrane Shrinking
Drugs

8. Expectorants
Expectorants are drugs that increase
 The bronchial secretion
 Enhance the expulsion of mucus by air
passages of the lung.

9. Classification
 Inhalant expectorants: Turpentine,
Benzoin, Eucalyptus oil etc.
 Ingested expectorants: Sodium
iodide, Potassium iodide etc.
 Mucolytic expectorants: Ambroxol ,
Acetylcystene etc.

10. Cough
H2O + glycoprotein linked together by disulphide
bond form polymer
In pathological state this glycoprotein bond with
exudates of plasma protein and form lanse polymer
Mucus become more viscous. Mucolytic agent free
sulphydryl group that open the disulphide bond of
mucous
viscosity. So cough comes out.
MOA of Expectorants:

11. Indication
 Non productive cough
 Bronchitis
 Emphysema
Side Effects
 Dizziness
 Drowsiness
 Nausea
 Vomiting

12. Respiratory Stimulants
Respiratory Stimulants are drugs that
 Act on central nervous system
 Increase respiratory rate and tidal volume
 Thus increase the urge to breathe
Eg. Ammonia Gas, Caffeine, O2+ CO2

13. Mechanism of Action
Respiratory Stimulants
Stimulation on Central Nervous System
Stimulates the Chemoreceptors in the
carotid bodies of carotid artery
Leading to increase the release of
transmitters
Increasing the heart & breathing rate
Relaxing the Bronchi

14. Indication
 Respiratory stimulation of neonates
 Anesthetics
 Severe Pneumonia
 Pulmonary edema or Emphysema
Side-effects
 Tremor
 Rapid heart rate
 Vomiting
 Sweating

15. Antitussives/ Cough Sedatives
Used to
 reduce the incidence of Cough
 depression of cough center
Types:
1. Direct acting
eg. Oxolamine, Chlorpheniramine, Promethazine
2. Centrally acting
eg. Codeine, Morphine, Noscaprine

16. Mechanism of action
Act on CNS (Central Nervous System)
Depressing the medullary cough center
Suppress the cough reflex through the
suppression of vagus nerve impulse
Reduces the discharge of nerve impulses to
the muscle that cause coughing
Increase threshold of cough centre.
This reduce viscosity. So, cough come out

17. Indication
 Non productive cough
 Disturb in sleep
 Hernia
 Piles
Side-effects
 Ataxia
 Drowsiness
 Sedative
 Constipation

18. Bronchodilator
Agents which
 Relax the smooth muscles of respiratory
Airways
 Relieves the dyspnea
 Removes the stimulation of Coughing
Eg. Atropine, Adrenaline, Salbutamol, Pilocarpine

19. Mechanism of Action
Bronchodilators (Salbutamol)
Acts on β2 receptor
Stimulation of adenylate cyclase
Increase cAMP production
Phosphorylates the myosin kinase
Mast cell membrane
stabilization
No histamine release
No bronchoconstriction
Relaxation of smooth muscle
Bronchodilation
Selective β2 agonist:

20. Classification
1. Sympathomimetic
Eg. Salbutamol, Turbutaline
2. Methyxanthines
Eg. Aminophyline
3. Spasmolytic
Eg. Atropine
4. Surfactant-
Eg. Pilocarpine

21. Indication
 Severe acute asthma
 Chronic asthma
 Chronic bronchitis
 Emphysema
Side-effects
 Drowsiness
 Convulsion
 Headache
 Tachycardia

22. Membrane Shrinking Drugs
1.Decongestants
Eg. Naphazoline
2.Corticosteroids
Eg. Prednisolone
3. NSAIDs
Eg. Flumixine
4.Antihistamines
Eg. Diphenhydramine