Asthma drugs Flashcards
What are the aims of drug treatment?
Reduce inflammation, prevent brochoconstriction, and restore airway calibre.
At what different stages are what drugs used?
Bronchodilator is used to treat the first asthma response- bronchospasm.
Anti-inflammatory drugs are used to treat the later response of inflammation.
What are the four types of bronchodilator?
B2 adrenergic receptor agonsits.
Theophylline
Muscarinic receptor agonists
Leukotriene receptor antagonists.
What are the actions of beta 2 adrenergic receptor agonists?
Act directly on the beta 2 adrenoreceptors in brochiole smooth muscle to relax the muscle.
Inhibit mediator release from mast cells and monocytes.
Can act on cilla to increase mucus clearance.
Explain the activation pathway of beta 2 adrenoreceptors.
Beta 2 agonists bind to the receptor on the G-protein. This activates the G protein which activates adenylate cyclase. This causes ATP to be converted to cAMP. This activated PKA which leads to protein phosphorylation. Causing muscle relaxation.
What are short acting beta 2 adrenergic receptor agonists.
Affects can be seen after 30 minutes and their effects last up to 4-6 hours.
Examples are salbutamol and tolbutamide.
What are the long acting beta 2 adrenergic receptor agonists?
Salmeterol
Last up to 12 hours.
Can be used twice daily with patients that aren’t on glucocorticoids.
What are the unwanted effects of beta 2 agonists?
Absorption into the systemic circulation
Tremor
Development of tolerance- however this can be resolved with glucocorticoids.
What is theophylline?
Bronchodilator used to treat the first phase of asthma.
Contains xanthine
Inhibits PDE
Second line drug- used when response to beta 2 is inadequate.
What are the unwanted side effects of theophylline?
CNS stimulant causing tremor and sleep disturbance.
Absorbed into the cardiovascular system stimulating heart causing vasodilation.
Absorption into the GI tract causing anorexia, nausea and vomiting.
What are muscarinic receptor antagonists?
Bronchdilators that are used when B2 agonists are insufficient.
Fast acting- 3-5 hours.
Administed by an aerosol- poorly absorbed so therefore few unwanted side effects.
List an examples of muscarinic receptors.
Iprotropium
What are the actions of muscular receptors
Bronchodilators
Inhibit mucus secretion
Increase clearance of bronchial secretions.
Block ACH at muscarinic receptors.
How does ACH causes bronchoconstriction with asthma.
People with asthma have raised levels of ACH. ACH binds to receptors in smooth muscle causing constriction. Blocking the receptors thus prevents bronchoconstriciton.
What are leukotriene receptor antagonists.
Bronchodilator.
Administered orally.
Used to prevent exercise induced and aspirin asthma.
Used in conjunction with beta 2.
What are examples of leukotriene receptor antagonists
Montelucast
Zarfirlukast.
What are the actions of leukotrine antagonists?
Act on cysteinyl-leukotrine receptors.
Prevent the actions of LTC and LTD- the spasminogens that stimulate mucus secretion.
There are few unwanted side effects- headaches and GI disturbances.
What are the main types of anti-inflammatory drugs?
Glucocorticoids- e.g beclometasone and budesonide.
What are the actions of glucocorticoids?
Reduce production of inflammatory mediations, LTC and LTD spasminogens.
Therefore reduce bronchospasm and reduce the recruitment and activation of inflammatory cells.
What are the clinical uses for glucocorticoids?
Used for patients receiving regular broncholiators.
Used for severe asthma.
Given IV as hydrocortisone and oral predisolone for acute exacerbations.
What is a cromoglicate?
A cromoglicate can reduce both early and late phases of responses.
Reduces bronchial hyper-reactivity.
Effective against asthma caused by antigen, exercise and irritants.
However not all asthmatics respond.
What is an example of a cromoglicate?
Nedocromil sodium
What are the mechanisms of cromoglicate?
Mast cell stabiliser
Side effects cause irritation of URT and hypersensitivity.
What are the clinical uses of cromoglicate?
Used in prophylactic to prevent both phases of an attack. Most effective in children.
What are biologic agents?
A new development of recombinant DNA from IgG1.
Give an example of a biologic agent.
Omalizumab
What are the mechanisms of biologic agents?
Inhibit IgE
What are the unwanted side effects of omalizumab?
Anaphylaxis
Malignancies.
How would you treat mild asthma with rare attacks?
Beta 2 agonist as and when required.
How would you treat mild asthma with more frequent attacks?
Glucocorticoid and beta 2.
