Asthma Pharmacology

1. Asthma Pharmacology Dr. Douglas McBean Subject Lead: Dietetics, Nutrition & Biological Sciences Programme Leader: BSc(Hons) Applied Pharmacology Senior Lecturer in Physiology & Neuroscience

2. Asthma • Asthma is an occlusive respiratory disorder

3. Asthma • Many people think asthma and wheezing are the same thing. • wheezing is only one sign of asthma • many other things besides asthma can cause wheezing • because of this confusion, the term asthma is being replaced with a more accurate description: Reactive Airway Disease (RAD)

4. Asthma Pharmacology • Bronchial asthma • reversible airway obstruction. • Extrinsic • allergic • Intrinsic • nonallergic (nonspecific hyperreactivity) • Status asthmaticus • severe acute bronchospasm

5. Key facts • 5.4 million people in the UK are currently receiving treatment for asthma • 1.1 million children (1 in 11) and 4.3 million adults (1 in 12). • There were 1,468 deaths from asthma in the UK in 2015 (18 were children aged 14 years or under) • on average, 4 people per day or 1 person every 6 hours dies from asthma • An estimated 75% of hospital admissions for asthma are avoidable and as many as 90% of the deaths from asthma are preventable.

6. Key Facts • 42% of people with asthma say that traffic fumes stop them walking and shopping in congested areas • 56% of people with asthma are sensitive to pet allergens • Scotland • 368,000 people (1 in 14) are currently receiving treatment for asthma • 72,000 children and 296,000 adults.

7. Children, parents and asthma • One in 11 children has asthma and it is the most common long-term medical condition. • On average there are two children with asthma in every classroom in the UK • The UK has the highest prevalence of asthma symptoms in children worldwide.

8. Children, parents and asthma • If one parent has asthma, the chance of their child developing asthma is approximately double that of children whose parents don't have asthma. • Every 21 minutes a child is admitted to hospital in the UK because of their asthma. • Smoking during pregnancy significantly increases risk of your baby being wheezy or having breathing difficulties. • Children whose parents smoke are 1.5 times more likely to develop asthma. Nearly a third of all long-term childhood illnesses are due to doctor-diagnosed asthma.

9. The costs of asthma • Asthma costs the NHS around £1.1 billion per year • The estimated annual cost of treating a child with asthma (£181) is higher than the cost per adult with asthma (£162) • 12.7 million working days lost due to asthma

10. Triggers of Asthma • Allergens • common allergens include pollen, mould, animal hair or fur, household dust/dust mites, cockroaches, and certain foods • Infections • both bacterial and viral infections can irritate the airways, triggering asthma attacks • Sinusitis • inflammation of the nose and nasal airways; during a sinus infection, mucous draining into the nose, throat, and lungs can cause asthma symptoms.

11. Triggers of Asthma • Irritants • strong odours and sprays (perfumes, household cleaners, paints, and varnishes) • certain chemicals like coal, chalk dust, and talcum powder; air pollutants; tobacco smoke; changing weather conditions (e.g. cold weather). • Smoke • inhaling smoke from cigarettes or fires harms the airways and is especially hard on the airways of people with asthma • cigarette smoking is responsible for more than half of the cases of asthma in people over 40 years of age.

12. Triggers of Asthma • Exposure to irritants on the job • many cases of asthma are worsened or even caused by exposure to vapours, dust, gases, or fumes in the workplace • About 5% - 20% of adults have attacks triggered by sensitivities or allergies to sulphites and to medications such as aspirin, ibuprofen, indomethacin, and naproxen • Sulphites are often used to preserve foods and beverages, including tuna, foods available at salad bars, dried apples and raisins, lemon juice, grape juice, wine • Emotional anxiety • strong emotions and nervous stress

13. Asthma • Those with RAD have bronchial passages that are more sensitive to irritation than normal • hypersensitivity leads to inflammation and swelling in the tiny airways deep in the lungs • Inflammation in turn causes • excess mucus production • tightening of airway muscles that wind around the bronchial tubes like laces • Combination of swelling, mucus, and muscle tightening all cause narrowing of the airways • wheezing usually results - dry cough sometimes only sign

14. Characteristics of disease • Bronchoconstriction • Mucus secretion - often viscous • Release of mediators from mast cells and basophils • Mucosal oedema

15. Chain of events in asthma

16. Pharmacological intervention • Bronchodilators • adrenoceptor stimulants • antimuscarinic bronchodilators • theophylline • Corticosteroids • Cromoglicate • Mucolytics

17. BRONCHODILATORS • Adrenoceptor stimulants • stimulate β2 adrenoceptors in airway smooth muscle • produce smooth muscle relaxation and bronchodilatation • examples • salbutamol • terbutaline • almeterol • albuterol • fenoterol • ephedrine

18. Bronchodilators • Anticholinergic (antimuscarinic) bronchodilators • ipatropium bromide • block vagally-mediated (acetylcholine-elicited) bronchospasm (result is bronchodilation) • Theophylline / aminophylline • phosphodiesterase inhibitor • therefore inhibit metabolism of cAMP by phosphodiesterase • increase cAMP stimulation of β-adrenoceptors

19. Corticosteroids • Anti-inflammatory glucocorticosteroids: • reduce airway inflammation • hence reduce oedema and mucus secretion • examples • Beclometasone dipropionate (Becotide) • Budesonide (Pulmicort) • Fluticasone (Flixotide) • the major side effect of inhaled glucocorticosteroids is fungal infection in pharynx and larynx.

20. Cromoglicate • Sodium cromoglicate (Intal) and Nedocromil sodium (Tilade): • used prophylactically by inhalation route • Very effective in children • Very safe • mode of action not completely understood • has a number of anti-inflammatory actions including stabilisation of mast cells

21. Mucolytics • Mucolytic agents: • Dornase Alfa (Pulmozyme) • reduces H+ bonds in hard mucus plugs to free -SH groups, thereby softening the mucus • administered by inhalation

22. Summary • What is asthma • Facts & Figures • Symptoms • Pharmacology