CPDIN OBJECTIVES
After completing this module you should: • Explain the differences between COPD and Asthma • Define Asthma. • List the drugs used to manage Asthma • Describe the stepwise approach to management • Consider appropriate inhaler technique and device selection
AUTHOR John Hamill, Lead Practice Based Pharmacist
This article was written by the author and supported by NAPP Respiratory
have asthma, you have very sensitive airways – the tubes that carry air in and out of your lungs. Certain triggers can cause your airways to become inflamed and tighten when you breathe. Triggers can include stress, exercise, cold air, and breathing in particular substances such as smoke, pollution or pollen. (British Lung Foundation definition)
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Key facts • 5.4 million people in the UK are currently receiving treatment for asthma: 1.1million children (1 in 11) and 4.3 million adults (1 in 12).
• In 2016 1,410 people in the UK died from asthma.
• Asthma attacks hospitalise someone every 8 minutes; 185 people in the UK are admitted to hospital because of asthma every day (a child is admitted every 20 minutes)
The anatomy of an asthmatic attack Whilst everyone’s airways will react to inhaled irritants, asthmatic patients, due to the underlying low-grade inflammation, over-react. An asthmatic attack occurs in two stages. Initially there is an early asthmatic response characterised by a fall in peak flow rate due to bronchoconstriction. This will resolve within about 3 hours. In atopic
22 - SCOTTISH PHARMACIST
sthma is a common, long- term disease that requires ongoing management. If you
individuals excess immunoglobulin E (IgE) is produced and attaches to mast cells. Interaction will allergens cause de-granulation of the mast cells leading to the release of a range of bronchospastic mediators including; histamine, bradykinin and leukotrienes and this results in a late asthmatic response that can last for 12 to 16 hours.
The chronic inflammatory response results in characteristic changes; • Airway epithelium may be shed • Excess mucus secretion • Mediators affect autonomic control of airways resulting in bronchoconstriction
Management of Asthma Non-drug Smoking cessation will improve the management of asthma. The benefits of taking exercise, eating a healthy diet and correcting obesity are evident. Overweight/obese patients will suffer greater morbidity from their asthma. Avoiding allergens (where possible) will help.
Drug Management Drug management of asthma can be spilt into two therapeutic groups; bronchodilators (relievers) and anti- inflammatory agents (preventers).
Bronchodilators Beta-2-adrenoreceptors are found within the bronchial smooth muscle. Beta-2 agonists interact with these receptors resulting in bronchial smooth muscle relaxation. In addition,
FOCUS ASTHMA This module is about asthma ASTHMA
Differences between
Possibly Often Uncommon Variable Common Common
Asthma and COPD Smoker
Symptoms under age 35 Persistent ‘wet’ Cough Breathlessness Night time waking with SOB and/or wheeze
Significant daily or day to day variability of symptoms
they inhibit mediator release from mast cells and increase mucociliary clearance.
• Short acting(SABA) Salbutamol, Terbutaline
• Long-acting(LABA) Salmeterol, Formoterol
Due to their rapid, almost immediate, onset of action short-acting beta-2- agonists are mostly administered by inhalation as a dry powder (DPI) or a metered dose inhaler (MDI). Beta-2-agonists are not fully selective for beta-2-receptors and can affect beta-1-receptors resulting in the common side-effects, including; tremor, cramps, palpitations, tachycardia, hypokalaemia and peripheral vasodilation.
The long-acting beta-2-agonists have a duration of action of approximately 12-15 hours. They are not intended for relief of acute symptoms but symptom prophylaxis. They are therefore indicated for the control of nocturnal asthma and to prevent exercise induced bronchospasm.
Anticholinergics (antimuscurinic bronchodilators -LAMA)
• Tiotropum
Anticholinergic agents competitively inhibit the action of acetylcholine at the muscurinic receptors resulting in bronchodilation. Tiotropium is now licensed for the treatment of Asthma; it is not appropriate for the relief of acute bronchospasm.
Uncommon Nearly all Rare Common Persistent & progressive Uncommon COPD
These drugs should be used with caution in patients suffering from glaucoma, prostatic hyperplasia and bladder outflow obstruction. Side- effects include dry mouth, nausea, constipation and headache.
Methyxanthines • Theophylline
These drugs are not effective when administered by inhalation. They have a complex and uncertain mode of action but are effective bronchodilators licensed for the management of asthma. They relax smooth muscle, inhibit mediator release, increase mucociliary transport and suppress oedema.
Theophylline has a narrow therapeutic window (5-20 micrograms/ml) -great care must be taken administering the drug concomitantly with drugs known to induce/inhibit drug metabolism. Common drugs that raise plasma theophylline levels include; cimetidine, ciprofloxacin, clarithromycin, the COC pill and diltiazem. Drugs that lower theophylline levels include; carbamazapine, phenobarbitone, phenytoin, rifampacin and cigarette smoke.
Side-effects associated with theophylline and might be associated with toxicity include; nausea and vomiting, abdominal discomfort, CNS stimulation and sleeplessness. At higher plasma levels (above 35 micrograms/ml) SE’s are potentially lethal including; arrythymias, palpitation, tachycardia and convulsions.
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