DRUGS ACTING ON RESPIRATORY SYSTEM

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

PARTS OF RT SYSTEM

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

PRINCIPLES….. Early Stage Dry harsh, painful & entirely useless cough

TREATMENT:i. To increase mucous Secretionii. Reduce frequency of coughiii. Prevent stimulation on mucosa by coating the

mucosaiv. Centrally depressing cough center

CONTD.. Recovery StageExcess mucus & Tissue debris in airwaysPrevent the free air passage & stimulate coughing

TREATMENT:i. To increase the fluidity of mucusii. Stimulate the activity of cilia thus all debris

expelled by coughing

e

ExpectorantsRespiratory

stimulantsAntitussive Bronchodilator

COMMONLY USED DRUGS…

Membrane Shrinking Drugs

Expectorants

Expectorants are drugs that increase

The bronchial secretion

Enhance the expulsion of mucus by air passages of the lung.

Classification

Inhalant expectorants: Turpentine, Benzoin, Eucalyptus oil etc.

Ingested expectorants: Sodium iodide, Potassium iodide etc.

Mucolytic expectorants: Ambroxol , Acetylcystene etc.

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:

Indication Non productive cough Bronchitis Emphysema

Side Effects Dizziness Drowsiness Nausea Vomiting

Respiratory StimulantsRespiratory Stimulants are drugs that Act on central nervous system Increase respiratory rate and tidal volume

Thus increase the urge to breatheEg. Ammonia Gas, Caffeine, O2+ CO2

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

Indication Respiratory stimulation of neonates Anesthetics Severe Pneumonia Pulmonary edema or Emphysema

Side-effects Tremor Rapid heart rate Vomiting Sweating

Antitussives/ Cough Sedatives

Used to reduce the incidence of Cough depression of cough center Types:

1. Direct acting eg. Oxolamine, Chlorpheniramine, Promethazine2. Centrally acting eg. Codeine, Morphine, Noscaprine

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

Indication Non productive cough Disturb in sleep Hernia Piles

Side-effects Ataxia Drowsiness Sedative Constipation

BronchodilatorAgents which

Relax the smooth muscles of respiratory Airways

Relieves the dyspnea Removes the stimulation of Coughing

Eg. Atropine, Adrenaline, Salbutamol, Pilocarpine

Mechanism of Action

Bronchodilators (Salbutamol)

Acts on β2 receptor

Stimulation of adenylate cyclase

Increase cAMP production

Phosphorylates the myosin kinaseMast cell membrane

stabilization

No histamine release

No bronchoconstriction

Relaxation of smooth muscle

Bronchodilation

Selective β2 agonist:

Classification

1. Sympathomimetic Eg. Salbutamol, Turbutaline

2. MethyxanthinesEg. Aminophyline

3. Spasmolytic Eg. Atropine

4. Surfactant-Eg. Pilocarpine

Indication Severe acute asthma Chronic asthma Chronic bronchitis Emphysema

Side-effects Drowsiness Convulsion Headache Tachycardia

Membrane Shrinking Drugs1.Decongestants Eg. Naphazoline

2.Corticosteroids Eg. Prednisolone

3. NSAIDs Eg. Flumixine

4.Antihistamines Eg. Diphenhydramine