Anti-Asthma drugs Flashcards
What is asthma?
Respiratory disorder- airways hyper responsive
Associated with airflow limitation
Bronchial inflammation
What is an asthma attack?
Construction of the airways caused by smooth muscle contraction, swelling, inflammation, excessive production of mucus.
Limiting the flow of air through the narrow bronchioles, wheezing on expiration.
Traps air in lungs, reducing efficiency of gas exchange
What are the symptoms of asthma?
Related to the narrowing of the airways.
Cough caused by irritation and attempt to clear airways
Symptoms are worse at night
Wheezing attacks
Shortness of breath
Cough
What triggers asthma?
Dust mites Exposure to allergens Cold, dry air- increases concentration of the fluid king the bronchi, causing histamine and leukotrienes to be released from mast cells. Cigarette smoke Excitement, stress, anger Drugs- aspirin, beta blockers
What are the long term aims of asthma therapy?
Abolish symptoms Maintain optimal lung function Prevent permanent lung damage Avoid unnecessary side effects Allow patent to remain symptom free for as long as they can
When does an allergic asthma attack occur?
- Sensitisation phase: 1st exposure to allergen. Activates the T cells
- Inflammatory mediators are secreted called interleukins and activate the B cells.
- B cells become plasma cells and secrete antibodies known as IgEs
- These bind to mast cells
- When re exposed to allergens, the allergen binds to the IgEs on the surface of mast cells, results in histamine release
- Re exposure prompts early face reaction immediately
- Late phase reaction: 3-10 hours
- Eosinophils can be very damaging to the lining of the airways.
What are bronchodilators?
They are relievers, relax the smooth muscles.
What is Salbutamol?
The most common from of bronchodilator (ventolin)
Which bronchodilator is longer lasting?
Salmeterol
For severe asthma, which drug is used?
Theophylline
Which bronchodilator blocks mucus secretion?
Ipratropium
What are the two categories of anti asthma drugs?
- Relieve symptoms
2. Stop symptoms occurring- take regularly
What does B2 adrenoceptor agonist do?
Relievers: Salbutamol, muscadine receptor antagonist, which reverse the bronchial constriction caused by parasympathetic stimulation and inhibit the rise in mucks secretion.
Can be used in addition to b agonist drugs: alkylanthines I.e. Theophylline
What are preventers?
Anti inflammatory, stop response of allergen.
Preventers-prophylactics- do not have bronchodilator activity. Work by reciting immediate and late phase asthmatic response. Reduce bronchial activity
Beclometasone
Sodium cromaglicate (steroid drugs)
Montelukast
What is glucocorticosteoids?
It is a prophylactic, may be taken orally, inhaled or IV.
Which receptor in the SNS is a target for drugs?
A1= blood vessels A2= VMC B1= Heart B2= Lungs, blood vessels, muscle spindles (targets for anti asthma drugs)
What does salbutamol do?
Similar structure to adrenaline
Selective to B2 receptors on the SNS
Widen the airways, smooth muscles relax
Explain the B2 agonists
Short acting drugs: Salabutimol, Terbutaline
Longer acting drugs: Salmeterol, formoterol
Inhaler or tablets
What are the side effects of B2 agonists?
Resting tremor
Increased heart rate
Decreased potassium
Nervous tension headache
What is a MDI?
Metered dose inhaler, contains a bronchodilator drug.
Breath-activated inhaler.
Why is inhalers not very efficient?
Following the correct use of MDI: 50% impacts on mouth 10% reaches the lungs 90% swallowed -depends on pt technique
What is an accuhaler?
Dry powder inhaler, activated by moving a lever on the side
- sharp intake of breath is sufficient to take in the drug
- device has a counter, let’s you know how much drug remains
What is the turbohaler?
Dry powder inhaler, can deliver 100 consecutive doses. Next dose ready when base moves back and forth.
- contains 200 doses
- desiccant keeps powder dry by absorbing moisture
- does not contain lactose, no taste when does administered
Describe the use of nebuliser in children.
Small plastic container filled withdraw solution
Compressor blows air/oxygen through the solution, makes aerosol/mist
Mist breathed in via mask or mouth piece
Severe asthma attack at GP or A/E department
What anti-asthma drugs are used as preventers?
Glucocorticosteoids via inhaler
Beclometasone is the most prescribed medicine, not aimed for rapid relief but helps control symptoms when taken routinely, oral inhalant or nasal spray
Budesonide-relief within 10’hours, Fluticasone, Mometasone
Relief- 3-7days, bioavailability poor, systemic side effects minimal
What are combination inhalers?
Beta 2 agonist and steroids
- Symbicort- budesonide/ formoterol
- SMART- Symbicort Maintenace And Reliever Therapy
- Fluticasone Salmerterol
What is the benefit of a combined inhaler?
Carry less inhaler with you.
What is the mechanism of action for glucocorticosteoids?
Synthesised from cholesterol= highly lipidphillic, can cross cell membrane
Once inside, bind to steroid receptor
Drug-receptor complex allows the drug to migrate across to the nucleus
Brings to DNS, induces or suppresses specific genes- protein production
i.e. GC inhibit transcription of cox 2 gene, resulting in reduced protein production, reduced inflammation
What are the side effects of glucocorticosteoids?
Candida Albicans (oral thrush) Dysphonia (hoarseness)
Can be reduced by rinsing month/ gargling or using a spacer
When is oral prednisolone used?
Treatment for acute asthma attack
7 days of high doses
In chronic asthma- combine with high does of inhaled steroids
What is the mechanism of action for oral prednisolone?
Suppresses the activity of the immune system and the release of inflammatory mediators, rapidly reduce symptoms.
What are the side effects of oral corticosteroids?
Buffalo hump- crushing syndrome
Increased abdominal fat- redistribution of fat
Crushing features- growth- children
Osteoporosis - decrease calcium absorption, increased calcium excretion via kidneys
Thinning of skin
Poor wound healing- inflammation has a key role in wound healing
Muscle wasting- protein breakdown
Hypertension
Moon face
Hyperglycaemia- increase and decrees of glucose production
What are the dangers of stopping steroid treatment abruptly?
Sudden withdrawal can result in acute adrenal insufficiency, pts ability to synthesise corticosteroids is suppressed
Unable to respond to stress from illness or trauma
Result: Addison crisis- pts have symptoms of shock. Can die in untreated.
What are anti-muscarininc brionchodilators?
Short acting relievers
Severe asthma: used alongside high doses inhaled corticosteroids
Block Muscarinic receptors, inhibiting bronchoconstriction I.e. Ipratropium
What is the mechanism of actions for M antagonist?
Slower to act than beta agonist, block the construction caused by activation of the PNS Because IPratropium blocks R receptors
Side effect: dry mouth (SNS), precipitate glaucoma
What are cromones?
Inhibits the release of chemicals from inflammatory cells called mast cells- prevents bronchospasm
Reduces allergen induced response and bronchospasm
Cromones stop the mast cells from releasing histamine to prevent symptoms occurring
What are leukotriene receptors antagonists?
Leukotriene receptor causes bronchoconstriction, release of inflammatory cells and increase section in the airways
Relax and prevent inflammation
May cause GI DISTURBANCE. Exeter induces asthma
Examples of leukotriene receptor antagonist
Montelukast
Zafirlukast
What is theophylline?
Oral/IV persistent symptoms/ severe acute asthma
Use withB agonist and or steroids
Blocks PDE enzyme in airways, causing muscle to relax
Anti-inflammatory effect
Side effects of theophylline?
Tachycardia
Palpitations
Headaches
Convulsions
What is the mechanism of action op for theophylline?
Blocks PDE enzyme, which breaks down cAMP into 5’AMP. So more cAMP is available to stimulate smooth muscle relaxation
What is Omalizumab?
Expensive drug
Antibody given SC, EVERY 2-4 weeks
Adults with severe allergic asthma not controlled with b agonist or steroids
Antibody that stops the IgE binding to receptors on the surface of mast cells and basophils
Prevents the release of pro- inflammatory mediators and reduces allergen-induced airways reaction
Side effects of Omalizumab?
Bruising
Pain
Small risk of anaphylaxis
What is the treatment strategy for asthma?
Mild to severe
- Inhaled shirt acting B 2 agonists (as needed) or inhaled Ipratropium or oral b agonist or theophylline
- Inhaled steroids
- Inhaled long acting b2 agonists with increased dose of inhaled steroids
- Short and long acting b2 agonist and inhaled steroids and and another drug such as Leukotriene receptor antagonist
- Continuation or frequent use of oral steroids and immunosuppressants
When should prophylactic treatment be considered?
If b2 agonist inhalation is needed more often than twice a week
If symptoms disturb sleep more than once a week
If the patient has suffered an exacerbation in the last 2 years
What is the therapy for acute asthma attack?
- Bronchodilators given via nebuliser
- Corticosteroids- route depends on severity, oral prednisolone or IV hydrocortisone
- Oxygen therapy needed if oxygen saturation of blood reduces are less than 93%
- If poor response then administer aminophylline injection for severe and acute attack
- Nebuliser enable deeper penetration into bronchial tree
What are the two main prescribed anti-asthma drugs?
Relievers: b agonist
Preventers: steroids
