PHARMACOLOGICAL BASIS OF
TREATMENT OF BRONCHIAL ASTHMA
Asthma - Greek word meaning “to
stay awake in order to breath” or
“difficulty in breathing”
Asthma is a chronic inflammatory
disorder of the airways.
Chronically inflamed airways are
hyper responsive; they become
obstructed and airflow is limited by :
2. Mucus plugs
3. Increased inflammation when
airways are exposed to various risk
Asthma is a chronic inflammatory disease in
which the patient suffers with reversible
episodes of airways obstruction due to
Age: Pediatric group most affected
Sex: within 10 years of age male:
female ratio(2:1) and equal in adults.
Allergens – Food, Inhalants, Bacteria .
Asthma affects 8% in adults and 10% in children.
Asthma is common in industrialized nations such
as Canada, England, Australia, Germany, and
New Zealand, where much of the data have
The prevalence rate of severe asthma in
industrialized countries ranges from 2-10%
Histamine, LTC4, LTD4, LTB4,
Cytokines, Adenosine, PGD2, PAF,
ECP and Neuropeptides
β 2 AGONISTS
Cause inflammation, oedema,
bronchospasm, muscus secretion,
β 2 AGONISTS
Bronchial Smooth Muscle
Sensory C fiber
ASTHMA MANIFESTS AS
Recurrent episodes of wheezing
Goals of asthma therapy
› To prevent chronic and troublesome symptoms
› To maintain near normal pulmonary function
› To maintain normal activity levels (including
exercise and other physical activity)
› To prevent recurrent exacerbations of asthma
and minimise the need for emergency
department visits to hospitalizations
› To provide optimal pharmacotherapy with
minimal or no adverse effects
› To meet pts & families expectations and
satisfaction with asthma care.
1. β2-Selective adrenoceptor
most widely used sympathomimetics for the
treatment of asthma at the present time.
Short acting:- albuterol-Terbutaline
used only for acute attack of bronchospasm
Long acting:- salmeterol –formeterol
used for only prophlaxis and not for acute
attack of bronchospasm.
Selective β2 receptor agonist
mechanism of action
Selectively β2 receptor agonist
Route of administration:
Usually delivered via a metered dose inhaler
with immediate effect
Orally used in children.
i.v used for acute attack.
2. Adverse effect:
Cardiac arrhythmias (at high dose has β1
Tolerance to β agonist (tachyphylaxis)
Skeletal muscle tremors.
Agonist of α and β receptor
Adverse effect of cardiovascular system usually
occurs thereby less usable
Similar action to Adrenaline
Less usable for central excitation
Mechanism of Action: It stimulates the β2 receptors
and cause bronchodilation.
Rout of administration:
Worsening of angina and even arrhythmias
They are divided into two types:
1. Salt complex: increased water solubility
without augmentation of pharmacological
action, such as: aminophylline.
2. Slow-release form: small fluctuation of blood
concentration after oral administration thus used
for nocturnal attack of asthma.
Mechanism of action
Inhibit activity of PDE
3. Inhibition of the cell surface receptor of
Route of administration:
Metabolised by P450 enzyme system
Direct positive chronotropic and inotropic
effects on the heart.
In large dose, these agents also relax
vascular smooth muscle.
It has a narrow therapeutic index
Its therapeutic and toxic effects are related to
its plasma concentration.
<20mg/L: nausea, vomiting, headache,
anxiety, abdominal discomfort.
Act by competitive blocking of muscarinic
receptors (M3 subtype)
2. Route of administration:
Metered dose inhaler e.g Ipratropium bromide
Used as adjuncts to β2-adrenoceptor agonist in
treatment of asthma.
Depress the inflammatory response in bronchial
mucosa thus diminish bronchial
Anti-inflammatory effect (inhibit phospholypaseA2)
Route of administration
Metered dose inhaler: (deeply & slowly inhale)
Intravenous used for: severe asthma status
asthmaticus (prednisolone or hydrocortisone)
Monoclonal anti IgE antibody
Mechanism of action:
It prevents the binding of IgE to mast cell & thus
prevents mast cell degranulation
Rout of administration:
i.v or s.c
Redness, stinging, itching, induration.
NSAIDS like aspirin,ibuprofen,diclofenac etc.
(paracetamol can be used)
1. Mild episodic asthma
Inhaled short-acting beta2
agonist at onset of each episode (step-1)
2. Seasonal asthma
start regular inhaled cromoglycate/low dose
inhaled steroid(200-400micro g/day) 3-4 wks before
anticipated seasonal attacks continue till 3-4 wks
after the season is over treat individual episodes
with inhaled short acting β2 agonist.
3. Mild chronic asthma with
regular inhaled cromoglycate, episodic-short
acting β2 agonist(step-2)
4. Moderate asthma with frequent
increases doses of steroid (up to 800μg/day)
+inhaled long acting β2 agonist(step-3)
5. Severe asthma:
Regular high dose inhaled (steroids 800-2000μg/day)
though a large volume spacer device + inhaled longacting β2 agonist (salmeterol) twice daily
6. Status asthmaticus
Any pt of asthma has the potential to develop
acute severe asthma which may be life
upper respiratory tract infection is the most
Management of status asthmaticus
Hydrocortisone hemisuccinate 100mg
followed by 100-200mg 4-8 hourly infusion
Nebulized salbutamol (2.5-5mg)+ipratropium
bromide (0.5mg) intermittent inhalations driven
High flow humidified oxygen inhalation.
Salbutamol/terbutaline 0.4mg i.m/s.c may be
added, since inhaled drug may not reach
smaller bronchi due to severe
Intubation & mechanical ventilation, if needed.
Treat chest infection with intensive antibiotic
Correct dehydration and acidosis with
saline+sod. bicarbonate/lactate infusion.
Aerosol Delivery of Drugs
High local concentration in bronchioles
Low systemic side effect.
Optimal particle size for deposition in
airways – 1to 5μm
Four classes of antiasthma drugs, i.e β2 agonists,
anti-cholinergics, cromoglycate and
Glucocorticoids are available for inhalational use.
They are aimed at delivering the drug to the site
of action so that lower dose is needed and
systemic side effects are minimized.
Most asthma patients are now maintained on
inhaled medication only.
Pressurized Metered Dose Inhaler
In pMDI drug is dissolved or suspended in
propellant under pressure and when actuated
releases a predetermined dose.
Pressurized MDI can be used with spacer or
User of spacer improves drug deposition in lungs
and reduces oropharyngeal drug deposition.
Use of spacer reduces oropharyngeal drug
deposition by 10-15 folds when compared to pMDI
Spacer acts as reservoir for drug from which
patients can breathe easily.
Depending on patient’s technique, drug
delivery varies from 7 to 20%.
An oropharyngeal drug deposition is about
80% with pMDI.
The particle size distribution through HFA was 1.07
micrometer and that of with CFC is 3.36
Lung deposition of drug with HFA is 50% while with
CFC it is 10-20%.
With HFA the oropharyngeal deposition is 30%
whereas with CFC it is 90-94%.
Slow (3-5 secs) inhalation or tidal breathing
immediately following actuation
Easier to use than MDI alone
Recommended for anyone using MDI
Nebulizer convert a liquid solution or
suspension into an aerosol using either a jet
or ultrasonic energy.
Aerosol is then delivered to the patient
through either a face mask or a
Nebulzer requires least patient
cooperation and coordination.
Nebulzers are preferred in patients who
are unable to use other devices or in
acute attacks when inspiratory flow is
Only about 13% of the dose used is deposited
in the lungs.
The doses used in nebulizers are higher than
those used in other aerosol devices.
Therefore patients will receive 10-20 times the
dose received from a MDI.
Dry Powder Inhaler (DPI)
In PDI drug is provided as micronized particles in
large aggregates with or without carrier
Drug delivery in DPI depends on patient’s
inspiratory effort to disperse the drug and deliver it
to the lungs.
Drugs deposition in lungs with DPI is 15-40% with
considerable inter device variability and drug
deposition in oropharynx is <60%.
DPI dose not require propellants and hand breath
› Rapid (1-2 secs), deep inhalation; dose lost if
client exhales through device
› Population: > 4-5 years
1. Hold spinhaler upright with mouthpiece
downwards, and unscrew body
2. Put coloured end of spincap into cup of
propeller, making sure it spins freely
3. Screw the two parts together and hold
horizontal. Move grey sleeve up and down
once or twice, this will pierce capsule
4. Breathe out gently, tilt head back, put
spinhaler into mouth so lips touch flange and
breathe in quickly and deeply
5. Remove spinhaler from mouth and hold
breath for about 10 seconds, then breathe out
6. If any powder is left in spincap, repeat steps
4 and 5 until it is empty
Always Demonstrate To The Patient How To Use
Asthma cannot be cured but can be
controlled with regular use of medications.
Asthma is treated with two types of medicines:
Long term control
Long term control medicines help to reduce
airway inflammation and prevent asthma
Quick-relief,or “rescue", medicines relieve
asthma symptoms that may flare up.
Initial asthma treatment will depend on severity
of the disease.
Patient counseling on drug therapy should
concentrate on drugs used to relieve
symptoms, drugs used to prevent asthma
attacks and those drugs which are given only
as reverse treatment for severe attacks.