Drugs in Asthma Flashcards
What kind of condition is asthma?
An inflammatory condition
What are the symptoms of asthma
A recurrent obstruction of airflow in response to a non-noxious stimuli and bronchospasm
What is a non-noxious stimuli?
Stimuli that are too weak to affect non-asthmatic
Why do people get asthma?
Normally a combination of genetics and a trigger
Asthma is psychogenic; what is this?
It can be worse in different emotional situations i.e. it its worse in stress situation
Asthma is sometimes post-viral; what does this mean?
Can be brought out as the result of a viral infection
What is responsible for the onset of asthma in about 30% of cases?
A Trigger
What two ways can asthma be classified?
Atopic (extrinsic) and Non-atopic (intrinsic)
What does atopic mean?
Allergic
What does non-atompic mean?
Non-allergic
What is an antigen?
A foreign protein/modified protein that produces an antibody response
How do antigens cause the synthesis of antibodies?
Lymphocytes
Macrophage
Monocytes
and Mast cells
How are macrophages involved in antibody synthesis?
They present the antigen to be recognised by the lymphocytes
How are lymphocytes involved in antibody synthesis?
They recognise the antigen that the macrophage presents and they produce the antibodies
What are monocytes?
A type of white blood cell
How are monocytes involved in the immune system?
The differentiate into macrophages
What antibody do lymphocytes make that attach to mast cells?
IgE cells
What are mast cells?
Cells that contain histamine and can have a antibody attached to them that once it recognises the antigen it will release its contents
What are mast cells?
Contains granules and can have a antibody attached to them that once it recognises the antigen it will release its contents
What 3 important things do these mast cells release upon recognition of the antigen?
- Histamine
- Platelet activating factor (PAF)
- Leukotrienes
What do mast cells release?
Chemical mediators called cytokines
What are 3 other things sometimes released from mast cells?
- Prostaglandins
- Thromboxanes
- Interleukins
What is the effect of the cytokines the mast cells release and what symptoms do they produce?
- Oedema which leads to bronchial inflammation
- Smooth muscle contraction (broncial smooth muscle)
- Pain/itching
- Vasodilitation
What is the definition of an allergy?
An innappropriate immune response
In terms of allergy what varies depending on the tissue?
The form of the reaction and the mediators released
What are the symptoms of an allergic reaction involving the gut?
Vomiting
What are the symptoms of an allergic reaction involving the skin?
A rash or itchyness
What are the symptoms of an allergic reaction involving the eye or nose?
Hypersecretion
What are the two stages of asthma?
The intermediate and late phases
What is the intermediate stage of asthma?
The initial response to the allergen
What two things does the intermediate stage of asthma involve in terms of reaction?
Bronchoconstriction (bronchial smooth muscle contraction) causes the airways to contract and vasodilation
What happens to the force expiratory volume in one second (FEV1) during the intermediate phase of asthma when the trigger is applied?
It drops dramatically due to bronchoconstriction
What are the two stages of asthma?
The immediate and late phases
What is the immediate stage of asthma?
The immediate response to the allergen (up to an hour)
What two things does the immediate stage of asthma involve in terms of reaction?
Bronchoconstriction (bronchial smooth muscle contraction) causes the airways to contract and vasodilation
What happens to the force expiratory volume in one second (FEV1) during the immediate phase of asthma when the trigger is applied?
It drops dramatically due to bronchoconstriction
What is anaphalaxis?
When the allergic reaction is extreme and you can’t breathe rather than just become breathless
What is the late stage of asthma?
occurs from 3 to 10 hours after the initial prolongs the asthma attack
How does the late stage differ from the immediate?
More severe congestion and inflammation than seen in the immediate phase
What happens to the FEV1 during the late stage?
It decreases
What main things happen during the late stage?
Hypersecretion leads to mucus build up
Inflammatory response
Bronchoconstriction and hyperactivity
What is status asthmaticus?
A sever condition in which asthma attackas follow each other without pause
What nervous systems innvervate and contract the lungs?
The parasympathic and sympathic divisons of the nervous system
Non-adrenergic non-cholingergic excitory nervous system
Sensory part of the nervous system
How could the sensory system affect the contractability of the lung?
Irritation of the sensory system leads to relflex constriction by the parasympathetic nervous system
How does the parasympathetic (cholinergic) affect contracility?
causes contraction
How does the sympathetic (adrenergic) affect contractility
causes relaxation
What is the NANC system?
Part of the autonomic nervous system whose transmitters are not acetylcholine or adrenaline
What system contracts the upper airways?
The parasympathetic
What transmitter causes contraction of the upper airways and what receptor do they bind to?
Acetylcholine on the muscarinic (m3) receptor
Which transmitters contract the lower airway muscles?
The excitatory NANC transmitters
Which transmitters relax the lower airway muscles?
The inhibitory NANC transmitters
What is an example of an inhibitory NANC transmitter?
Nitric oxide
What other transmitter causes relaxation of the lower airway muscles and what receptor does it act on?
Adrenaline on the B2 receptor
What is interesting about the relaxation of the lower airway muscles?
There is no sympathic nervous system innvervation it is only circulating adrenaline that causes relaxation
What system vasoconstriction of blood vessel smooth muscle?
The sympathetic nervous system
What transmitter and receptor of the sympathic nervous system are involved in contraction of blood vessel smooth muscle?
Through noradrenaline acts on the a-adrenoceptor1
What other transmitter and receptor are involved in vasoconstriction of blood vessels that is not supplied by the sympathic nervous system?
circulating adrenaline acting on b2 recceptors
Which systems act on the glands and control mucous secretion?
The sympathic and parasympathic nervous systems
What affect does the parasympathic nervous system have on mucous secretion?
It increases mucous secretion
What affect does the sympathetic nervous system have on the mucous secretion?
It decreases mucous secretion
What other factors could cause mucous secretion from the glands to increase?
inflammatory mediators and chemical/physical stimuli
What kind of drug therapy would be required during the immediate phase of asthma and why?
Smooth muscle relaxants to treat bronchospasm
What kind of drug therapy would be required during the late phase of asthma?
Sterioids like corticosterioids to treat inflammation
What 3 specific kinds of drugs would be used to treat the immediate phase?
- B2 receptor agonist
- Muscarinic antagonists
- Theophylline
What 3 specific kinds of drugs would be used to treat the late phase?
- Antihistamines
- Leukotriene antagonists
- Glucocorticoids
Name a Beta receptor agonist that could to treat asthma?
Salabutamol
How is salabutamol administered?
Inhaled
What transmitter does salabutamol mimic the action of?
Adrenaline
What does salabutamol do to treat asthma?
It relaxes the bronchial smooth muscle which increases the FEV1
Name a muscuranic receptor antagonist that can be used to treat asthma but is more useful in bronchitis?
Ipratropium
Does ipatropium have good or poor absorption and why?
Poor as it is N+ (ionised)
What is now the better replacement for ipatropium?
Tiotropium
How is tiotropium used to treat asthma?
It is a selective m3 muscarinic receptor antagonist, block contraction by the parasympathetic nervous system
How long does tiotropium last?
24 hours
What does theophylline inhibit and why is this useful in the treatment of asthma?
It inhibit phosphodiesterase which breaks down cAMP and gGMP; raising these two will lead to relaxation of bronchial smooth muscle
What is theophylline?
A bronchodilator
Apart from inhibiting phosphodiesterase what else can theophylline do?
It can increase the production of adrenaline and noradrenaline
What are some serious side effects of theophylline?
Heart arrythmias and convulsions
What are antihistamines useful to treat? What do they treat indirectly?
Hayfever but can indirectly treat asthma
What are leukotrienes?
Produced by mast cells are the main cause of inflammation in asthma
Name a leukotriene receptor antagonist that could be used to treat inflammation?
Montelukast
Glucocorticoids are good prophylactics. Why is this?
They reduce the permeability of blood vessels by blocking the leaky pores that lets lymphocytes out into site of infection
Glucocorticoids turn off your immune system. Apart from blocking leaky pores name two ways how do they do this?
They inhibit production of immune mediators
They reduce lymphocyte and mast cell numbers
Glucocorticoids are involved in the inhibition of which enzyme?
phospholipase A2
Why is inhibition of phospholipase 2 by glucocorticoids important?
It means COX-2 is blocked and cannot make prostaglandins, leukotrienes etc
What is the mechanism in which glucocorticoids inhibit phospholipase A2?
They bind a nuclear receptor which can regulate gene expression and produces more mRNA to synthesise the protein lipocortin (annexin-1) which inhibit phospholipase A2
