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PULMONOLOGY
2. Routes of
administration of
asthma drugs
Asthma treatment can be
administered in different
ways - inhaled, orally or
parenterally (by subcutaneous,
intramuscular, or intravenous
injection). The major advantage
of inhaled therapy is that
drugs are delivered directly
into the airways, producing
higher local concentrations
with significantly less risk of
systemic side effects. Inhaled
medications for asthma are
available as pressurised
metered-dose inhalers
(pMDIs), breath-actuated
MDIs, dry powder inhalers
(DPIs), soft mist inhalers, and
nebulisers (rarely indicated
for the treatment of chronic
asthma). Choice of delivery
device should be based on
correct technique and patient
preference, and be assessed
during asthma reviews. Most
patients make mistakes with
a pMDI alone. They are less
likely to do so if they also use
a large volume (500 ml) spacer
or holding chamber to improve
drug delivery, increase lung
deposition, and reduce local
and systemic side effects.
3. Classification of
asthma drugs
A classification of asthma drugs
based on current know ledge
of their mode of action is
represented in Table 3. They
may be:
» Relievers - short-acting
bronchodilators with rapid
onset of action that provide
acute relief of symptoms
» Controllers - drugs with
anti-inflammatory and/or
a sustained bronchodilator
action.
Treatment combinations are
necessary in patients with
more severe asthma or mild
asthma not responsive to low
dose inhaled corticosteroids.
3.1 Controllers
There are two groups of
controllers - those with
anti-inflammatory action
The Specialist Forum | Vol. 17 No. 4
(corticosteroids and leukotriene
blockers) and those with a
sustained bronchodilator action
(long-acting β2 agonists, long
acting anti-cholinergics and
slow- release theophyllines).
Anti-inflammatory treatment
is recommended for all patients
with chronic persistent asthma.
Inhaled corticosteroids are
the most widely studied and
recommended drugs in this
class. Leukotriene modifiers
are effective, but less so
than inhaled corticosteroids.
Theophyllines have also been
shown to have weak anti-
inflammatory effects.
3.1.1 Corticosteroids
3.1.1.1 Inhaled
corticosteroids (ICS)
Inhaled corticosteroids are
the mainstay of treatment for
patients with chronic persistent
asthma. The inhaled route is
preferred because delivery
directly to the lungs permits
the use of lower doses.
Through their anti-
inflammatory effects, inhaled
corticosteroids reduce airway
inflammation, decrease
bronchial hyperresponsiveness
and improve asthma control.
In addition, they may modify
airway remodelling and
prevent an accelerated
decline in lung function. Their
long-term use in adequate
doses has been shown to
decrease exacerbations and
mortality. There are several
inhaled corticosteroids
available and their equivalent
doses in comparison with
beclomethasone dipropionate
(BDP) are shown in Table 1.
Systemic absorption of
inhaled corticosteroids arises
from oropharyngeal absorption
and to a lesser extent from
drug deposited in the lungs.
This may be reduced by
the use of a spacer device
combined with mouth washing
after inhalation. The former
increases the fraction delivered
to the lung. Both measures
reduce the incidence of local
side effects such as dysphonia
and oropharyngeal candidiasis.
Inhaled corticosteroids are
generally administered twice
daily, but budesonide and
ciclesonide are also approved
for once daily use in milder
asthma. A low starting dose
is 200-500 μg/day of BDP
equivalent and a dose above
1000 μg/day is considered a
high dose. At higher doses,
the dose-response curve is
relatively flat but the risk of
systemic side effects may be
increased.
In older children and adults,
a preferred strategy to reduce
the dose of corticosteroids
and improve control is the
combination of long-acting
β2 agonists (salmeterol or
formoterol) with lower doses
of inhaled corticosteroids.
An alternative is the
combination of lower dose
inhaled corticosteroids with
leukotriene blockers, which
is a preferred combination in
younger children. If these are
unavailable, combination with
slow- release theophyllines is a
weaker alternative. Long-acting
β2 agonists and slow-release
theophylline must always be
used in combination with at
least low dose corticosteroids
Asthma
treatment can be
administered in
different ways -
inhaled, orally
or parenterally.
Table 1: Low, medium and high
doses of inhaled corticosteroids:
estimated clinical comparability
Adults and adolescents ≥12 years
Drug
Daily dose (mcg)
Low Medium High
Beclometasone dipropionate CFC 200-500 >500-1000 >1000
Beclometasone dipropionate HFA 100-200 >200-400 >400
Budesonide (DPI or HFA) 200-400 >400-800 >800
80-160 >160-320 >320
100 n/a 200
Fluticasone propionate (DPI) 100-250 >250-500 >500
Fluticasone propionate (HFA) 100-250 >250-500 >500
Mometasone furoate 110-220 220-440 >440
Ciclesonide HFA
Fluticasone furoate (DPI)
Children 6-11 years
Beclometasone dipropionate CFC 100-200 >200-400 >400
Beclometasone dipropionate HFA 50-100 >100-200 >200
100-200 200-400 >400
80 80-160 >160
Budesonide (DPI or HFA)
Ciclesonide HFA
Fluticasone furoate (DPI) Not yet studied in this age group
Fluticasone propionate (DPI) 100-200
>200-400
>400
Fluticasone propionate (HFA) 100-200
200-500
>500
110
220-400
>440
Mometasone furoate
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