Drugs In Asthma and Chronic Obstructive Pulmonary Disease

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Drugs In Asthma and Chronic Obstructive Pulmonary Disease

Bronchodilators

• Act on airway smooth muscle.
• Relieve bronchoconstriction within minutes
• Duration of action – Up to 4 hours
• Increase cAMP and adenylate cyclase.
• Side Effects:
• Fine tremor, tachycardia,
• Hypokalaemia, cardiac dysrhythmia especially in the elderly and IHD sufferers.
• Headaches, muscle cramps.
• Occasional paradoxical bronchospasm.

Example 1: salbutamol (Ventolin), terbutaline:

• Most commonly used short acting relievers.
• Usually inhaled or nebulised, but can be given oral, iv, sub-cut.

Example 2: salmeterol (Serevent), eformoterol (Oxis):

• Long acting β₂-agonists.
• Used as controllers.
• Administered by inhalation bd.
• Not suitable for acute attack.
• Useful in nocturnal asthma.
• Duration up to 12 hours.

Ipatropium Bromide (Atrovent)

• Inhaled anti-muscarinic with bronchodilator properties.
• Maximum effect after 1hour, Duration 6 hours.
• Used in COPD for patients irresponsive to β₂ stimulants
• Used in life-threatening asthma attack,
• Side Effects:
• Dry mouth, urinary retention.

Theophylline

• 12 hour duration. Acts via increase of cyclic AMP, dilating bronchial smooth muscle.
• Anti-inflammatory effect also.

Aminophylline

·         Given iv, in acute severe asthma.

·         Side effects:

o     Narrow therapeutic index.

o     Nausea, vomiting, tachycardia & anxiety.

Common Interactions: Cimetidine, Some antibiotics, OCP, phenytoin. Monitoring (including smoking) is therefore important.

(Adrenaline can also be used in severe asthma attacks.)

Disease Modifiers

Inhaled Corticosteroids

• Most potent anti-inflammatory treatment for asthma.
• Given prophylactically if patient uses β₂-agonists >once per day.
• Non-specific inhibition of inflammatory mediators
• Reduce bronchial mucosal inflammation.
• Examples: beclomethasone (Becatide), budesonide (Pulmicort), fluticasone (Flixotide).
• Side Effects:
• Oral candidiasis or dysphonia.
•  At high doses effects on adrenal and bone metabolism.
• Osteoporosis, child growth retardation.

Cromones(Preventers)

• Examples : sodium chromoglycate, sodium nedocromil
• Act via stabilising mast cells
• Less effective than corticosteroids
• Used in mild atopic asthma.

Leukotriene Antagonists(Controllers)

• New drugs e.g montelukast, zafirlukast.
• Drugs are arachidonic acid metabolite antagonists.
• Cause smooth muscle relaxation.
• Given orally.
• Well tolerated.

Education

• Avoidance measures –allergens, smoking and drugs
• Explanation for reasons for prophylactic therapy
• Relievers and preventers
• Home PEF charts
• Self management.

Treatment Strategies

Stepwise Treatment of Chronic Asthma – BTS guidelines.

1. Reliever – Short acting β₂ agonist

And

2. Preventers – Inhaled Steroids, cromones occasionally

And

3. Controller –             Long acting β₂ agonist

Theophylline

Leukotriene antagonists

Oral Steroids.

(See Added page)

Acute Severe Asthma – BTS Guidelines

1. High flow oxygen.
2. Nebulised salbutamol 5mg +/- ipratropium 0.5mg.
3. Prednisolone 60mg or i.v. hydrocortisone 200mg.
4. If bad – Add iv aminophylline or salbutamol.
5. Do not gives sedatives, perform CXR to exclude pneumothorax

Treatment of COPD – BTS Guidelines – COPD Escalator

1. Smoking cessation
2. Antibiotics for acute infections
3. Inhaled bronchodilators
4. Long acting bronchodilators
5. Oral corticosteroid trial
6. Influenza vaccine
7. Assessment for long term oxygen therapy
8. Assessment for nebuliser therapy.

Other Treatments

 Oxygen Therapy

• Venturi Mask or Hudson mask.

 Assisted Ventilation

• Non-invasive – CPAP and NIPPV.
• Invasive – ET-tube, ventilation.

Cough Suppressants e.g codeine linctus

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