Providing in-depth revision notes for asthma pathophysiology. Including the causes, symptoms, triggers, risk factors, treatment and diagnosis. Excellent revision for exam period or also just to use a guide for your own revision. Originally made for pharmacy course, however can be used for any cours...
Asthma
Genetics
Air passes down trachea
Allergens
into left or right lungs
RSV & HRV - viral infections
Pollution
Alveoli increase surface
Tobacco smoke - can be second hand
area of lungs to allow as
Obesity
much gaseous exchange
as possible. Triggers:
Common allergens
Dust/dust mites
Pollen
Symptoms: Cockroach urine
Wheezing Anything the body sees
as an allergen and Animal dander
Shortness of breath Mould
An inflammatory condition in Cough develops an immune
response for. Animal hair/fur
which there is recurrent reversible Airway hyper-responsiveness: Respiratory irritants
airway obstruction in response to Airway wall inflammation. Airborne pollutants
irritant stimuli that don’t affect Luminal obstruction of airways by mucus, Major narrowing of Cold air
non-asthmatic subjects. caused by hypersecretion of bronchial mucous lumen - inflammation
glands, along with infiltration by to stop spread of Each antibody
Inappropriate
Bronchiole hyper- inflammatory cells. pathogens is specific to one
immune response
reactivity is Vasodilation of the bronchial microvasculature allergen
to an allergen. Severe Chronic Asthma:
abnormal stimuli with increased vascular permeability and
which can result in oedema. Lungs are altered
bronchoconstriction. and start to
If microbe detected,
resemble a COPD-
these activate
like structure.
immune system
IgE binds to receptor on mass cell.
Dendritic cells are in lungs and have Where we
If allergen comes and binds IgE
detected allergen. use our Asthma can be managed/ Diagnosis of Asthma: antibodies, mass cell degranulates
Presents allergen to T CD4. antibodies prevented through physical Clinical history of wheezing/ and releases its contents, causing
Allergic response initiates Th2 pathway. methods, which give relief of breathlessness bronchoconstriction.
B cells divide rapidly to produce plasma the immediate phase and Any triggers
cells. prevention of the late phase. Family history
Plasma cells produce antibodies which Adrenergic Receptors:
are used to target breathing allergen. Found in Bronchodilators - Receptors
2 types:
bronchioles. Activate B2 receptors that respond to
a-adrenergic receptors
2/3 hours later If we stimulate it, it in the lungs and adrenaline
Instantaneous b-adrenergic receptors - beta-blockers
causes the causes blood vessels
bronchioles to dilate. & bronchioles to
2 phases of asthma
dilate.
Results in
relaxation of smooth Cyclic AMP:
muscle and Secondary signalling
widening of the molecule
Methylxanthines - Theophylline:
airway Serves as a molecular
Theophylline can be used as an add-on
SABA signal
therapy in the treatment of asthma, Adrenaline Salbutamol
MOA not yet fully understood.
Theophylline relaxes the smooth muscle Pharmacokinetics of Salbutamol: Phosphorylates
Absorption - It is well absorbed after Type of other targets
of the bronchial airways and neurotransmitter
pulmonary blood vessels. oral administration. LABA
Reduces airway responsiveness to Distribution - Salbutamol does not
histamine, methacholine, adenosine, and cross the blood brain barrier.
Can be prescribed if asthma
allergens. Metabolism - It is metabolised to
is uncontrolled by SABA
Theophylline competitively inhibits inactive metabolites in the liver.
alone
phosphodiesterase (PDE). Excretion - Salbutamol is excreted
PDE the enzyme responsible for breaking primarily in the urine and small
amount in the faeces. Anticholinergic:
down cyclic AMP in smooth muscle Used in addition to SABAs/LABAS.
cells, possibly resulting in Block effects of acetyl choline.
bronchodilation. Can activate Inhibition of mascara I’d GPCR leads
multiple pathways to muscle relaxation.
involved in
inflammation Reduce
Inhaled Corticosteroids:
inflammation/
Glucocorticoids are the main therapy
mucus.
in achieving anti-inflammatory
Pharmacokinetics of Theophylline: Increase B2-receptor
action in asthma.
Absorption - Well absorbed when taken orally as a rapid-release tablet or when concentration.
administered as a liquid solution. Bioavailability and rate of absorption of If inflammation is
controlled-release preparations are more variable and influenced by severe, can give oral
formulation and food intake. steroids -
Distribution - Distributes rapidly into fat-free tissues and body water. 40% is Glucocorticoids activate the Prednisolone
bound to plasma proteins, primarily to albumin, although blood pH values, the glucocorticoids receptor.
plasma protein content and the administration of concomitant drugs may vary Inhibits the inflammatory stimuli. Given as ICS -
this fraction. Theophylline passes freely across the placenta, into breast milk and Effects many genes implicated in this Beclomethasone
into cerebrospinal fluid. process. dipropionate
Metabolism - Theophylline is primarily eliminated by hepatic metabolism Decreases inflammation.
involving isoenzymes of the cytochrome P450 system. Age and disease are the
major endogenous factors influencing metabolism: clearance is markedly
Anti-inflammatory Steroids:
reduced in the neonates and elderly and increased in the first decade of life.
Leukotriene receptor Consider if:
Elimination - Renal elimination of unchanged drug accounts for 10 to 15% of
antagonist - Block -Asthma attack in the last 2 years.
the total elimination of the dose in adults and may increase to up to 50% in
leukotriene to reduce -Using inhaled SABA 3 times per
neonates. Therefore, in a normal adult, renal disease has no significant effect on
inflammation week or more.
theophylline
-Symptomatic 3 times per week or
clearance.
more.
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