This document discusses drugs used to treat respiratory disorders such as cough and bronchial asthma. It classifies drugs used for cough into pharyngeal demulcents, expectorants, antitussives, and adjuvant antitussives. Drugs for bronchial asthma include bronchodilators, leukotriene antagonists, mast cell stabilizers, and corticosteroids. Salbutamol is discussed as a selective beta-2 agonist bronchodilator used to treat asthma and COPD. Its mechanism of action and side effects like hypokalaemia and tremors are explained. Antihistamines are classified based on generation, with first-generation being more sedating and second-generation having higher selectivity

1. Drugs used in
Respiratory Disorders
Dr. Pravin Prasad
M.B.B.S., MD Clinical Pharmacology
Lecturer, Lumbini Medical College
7 March, 2019 (23 Falgun 2075), Thursday

2. By the end of the class BSN 1st
year students will be able to:
Classify drugs used in the treatment of:
Cough
Bronchial Asthma
Classify antihistamines
Explain the mechanism of action, indications
and adverse effects of:
Salbutamol
Cetirizine

3. Cough: Introduction
Is a protective reflex
Types:
Productive (Useful)
• Sputum produced
• Drains the respiratory tract
Non-productive (Useless)
• Needs to be supressed if tiring

4. Drugs used for cough:
Classification
Pharyngeal demulcents
Used for cough due to pharyngeal irritation
•Lozenges, cough drops, linctus containing
syrup
Expectorants (Mucokinetics)
Helps to cough out bronchial secretions and
clear airway
•Bronchial secretion enhancers: Guaiphenesin,
Ammonium chloride
•Mucolytics: Bromhexine, Acetylcysteine,
Carbocisteine

5. Drugs used for cough:
Classification
Antitussives
Acts by suppressing cough centre or
decreasing tussal impulses or both
•Opioids: Codeine, Pholcodine
•Nonopioids: Dextromethorphan
•Antihistamines: Chlorpheniramine,
Diphenhydramine, Promethazine
Adjuvant antitussives
Bronchodilators: Salbutamol, Terbutaline

6. Drugs used for cough:
Classification
Adjuvant antitussives
Useful in cough associated with
bronchospasm or bronchoconstriction
•Bronchodilators: Salbutamol, Terbutaline

7. Drugs used in Bronchial
asthma

8. Bronchial Asthma
Is an primarily inflammatory condition
Characterised by hyperresponsiveness of the
respiratory tract to various stimuli
Results into:
Narrowing of bronchial tree, and
Increased secretion, mucosal oedema and
plugging
Symptoms:
dyspnoea, wheezing, cough and

9. Drugs used in Bronchial
asthma
Bronchodilators
β2 Sympathomimetics: Salbutamol, Terbutaline
 Methylxanthines: Theophylline, Aminophylline,
Doxophylline
Anticholinergics: Ipratropium bromide, Tiotropium
bromide
Leukotriene antagonists: Montelukast, Zafirlukast
Mast cell stabilizers: Sodium cromoglycate, Ketotifen
Corticosteroids
Systemic: Hydrocortisone, Prednisolone
Inhalational: Beclomethasone, Budesonide,

10. Salbutamol
Highly selective for β2 receptors
Short acting: effect seen in 5 mins of inhalation
Acts by stimulating β2 receptors
Increases cAMP and leads to
Bronchial smooth muscle relaxation
•Reversible airway obstruction relived
Administered by inhalation, sometimes oral/
injectable

11. Salbutamol: Uses
Asthma
Terminate attacks of asthma
Chronic Obstructive Pulmonary Disease
Mild cases (severe cases- long acting drugs)
Acute exacerbation
Cough
When aggravated by bronchoconstriction
Hyperkalaemia

12. Salbutamol: Adverse effects
Hypokalaemia
Muscle tremor
Principle side effect
Throat irritation
When administered by inhalation route
Palpitation, restlessness, nervousness
Stimulation of β1 receptors in heart
Ankle oedema

13. Antihistamines

14. Antihistamines
Binds to histamine receptors and blocks the
activity of histamine
H1 antihistamines
•Conventional antihistamines
H2 antihistamines
•Used for decreasing gastric secretions
H3 antihistamines
•Unknown clinical uses

15. Conventional Antihistamines
Acts by blocking H1 receptors
Categorised into two generations
First generation
Second generation
•Less sedating
•Higher H1 selectivity
•Additional antiallergic mechanisms

16. Antihistamines:
Classification
First generation:
Highly sedative
•Diphenhydramine,
Promethazine
Moderately sedative
•Cyproheptadine,
Pheniramine
Mild sedative
•Chlorpheniramine,
Triprolidine
Second generation:
Fexofenadine
Loratadine
Desloratadine
Levocetirizine
Cetirizine
Ebastine

17. Antihistamines: Uses
Allergic disorders
 Itching, urticaria, seasonal hay fever, allergic
conjunctivitis and angioedema of lips, eyelids
Insect bite, Ivy poisoning
Idiopathic pruritis
Older antihistamines:
Common cold, motion sickness, cough,
Parkinsonism

18. Antihistamines: Adverse
effects
Mild sedation
Somnolence

19. Any queries?
Thank you.