L12 - Respiratory Pharmacology Flashcards
How is the airway smooth muscle in the lungs regulated?
by the autonomic nervous system:
- sympathetic = bronchodilaton
- parasympathetic = bronchoconstriction
What happens to the airways in asthma?
- asthma is chronic inflammatory disease of the airways
- contracted smooth muscle
- inflammation and swelling = decreased lumen diameter
- excess mucous
it is hard to breathe out
What are the types of intervention used for asthma treatment/management?
- preventers: anti-inflammatory compounds
- relievers: bronchodilators
What are the types of preventers for asthma?
- corticosteroids
- cromolyns
- leukotriene antagonists
What are the effects of corticosteroids in asthma?
- reduce number of airways inflammatory cells
- reduce damage to airways epithelium
- reduce vascular permeability
must be used regularly for beneficial effects: cannot help with long-term uncontrolled asthma
What are the administration routes for corticosteroids in asthma?
- inhalation
- oral
What is an example of an inhaled corticosteroid?
fluticasone
What is an example of an oral corticosteroid?
prednisolone - liquid or tablet
What are the benefits of an inhaled corticosteroid?
- need lower concentration of drug = very little into systemic circulation
- minimises potential for adverse reactions
What are some of the problems associated with inhaled corticosteroids?
- a lot of the drug is swallowed so difficult to get to the lungs
- problem with disposition around the mouth and upper airways - risk of fungal infection because immuno-suppressant
When is prednisolone given?
orally only for certain circumstances: early during acute asthma exacerbations or for chronic severe asthma
How is prednisolone given?
- given with oxygen (40-60%) and bronchodilators (salbutamol) because the steroid doesn’t take effect immediately while the bronchodilator does
- high dose (40-60 mg daily) for a short course (4-10 days) then stop
What are the adverse effects of oral corticosteroid?
- suppressing pituitary/adrenal function
- euphoria
- buffalo hump
- hypertension
- thinning of skin
- thin arms and legs: muscle wasting
- benign intercranial hypertension
- cataracts
- moon face with red cheeks
- increased abdominal fat
- avascular necrosis of femoral head
- easy bruising
- poor wound healing
- osteoporosis
hyperglycaemia - negative nitrogen balance
- increased appetite
- increased susceptibility to infection
- obesity
Why are leukotriene antagonists effective in asthma treatment?
leukotrienes cause bronchoconstriction so blocking their effect is beneficial:
- anti-inflammatory
- bronchodilation
- reduce vasoconstriction
What is an advantage of leukotriene antagonists over corticosteroids in asthma management?
- leukotrienes less potent because only target leukotriene pathway - less ADR
- steroid receptors are located throughout the body = more systemic side effects
What are the types of leukotriene antagonists?
- leukotriene receptor antagonists
- lipoxygenase antagonsts: inhibit the enzyme involved in the production of all leukotrienes
What drugs are examples of leukotriene receptor antagonists?
- montelukast
- zafirlukast
What drug is an example of lipoxygenase antagonists?
zileuton - inhibits 5-lipoxygenase
What are relievers in asthma treatment? What effect do they have?
- relievers are drugs that are used to manage the symptoms
- they modulate the ANS (B2) to cause bronchodilation
What effect do B agonists have in asthma?
- target B2 receptors
B2 receptors are found in the lungs and their activation causes bronchodilation with minimal effect on the heart
What are the types of B agonists in asthma treatment? Give examples
(reliever) SABA - Short Acting Beta Agonist:
- salbutamol, terbutaline
(controller) LABA - Long Acting Beta Agonist:
- salmeterol, formoterol
What is salbutamol used for?
- acute inhalation treatment of bronchospasm
- prevent exercise-induced asthma `
What is the onset and duration of salbutamol? When is it used?
onset: 10-15 minutes
duration: 2-5 hours
used on an “as required” basis - regular use shows no benefits
- not used for nocturnal asthma because the effects wear off
What are the adverse effects of SABAs?
at high doses:
- sympathetic NS activation = skeletal muscle tremor
- still has effect on heart = increased HR and force of contraction
