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Asthma Relieving Drugs
Treating acute severe asthma
Short acting beta agonists
Theophylline
Anticholinergics
Adrenaline
Systemic steroids
Desperate measures in severe asthma
Reliever drugs are -- well, drugs that relieve the symptoms of asthma. They are the drugs used
when a child has an acute attack of asthma, with wheezing, severe cough, inability to participate
in physical activity, and difficulty in breathing. Over the past few years, better and better drugs
have become available, along with devices to deliver the drugs directly to the lungs. This has
made reliever therapy very effective and safe.
However, we have also realized that the use of reliever drugs indicates that the child's asthma is
not well controlled. Frequent symptoms indicates that the airway inflammation and bronchial
hyperreactivity are out of control, and a review and readjustment of controller therapy are
required. Now that we have highly effective reliever drugs, we don't want to use them. And this
reflects the great change in asthma therapy - the aim is no longer to relieve the narrowing of the
airways. The aim is to see that it never happens, because acute attacks of asthma signify poor
disease control, which leads to irreversible lung damage in the long term.
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These are the mainstay of the acute asthma therapy today. Two drugs are commonly used -
salbutamol and terbutaline. The two drugs are fairly similar; they have quick onset of action, and
the action lasts 4-6 hours. They are available as oral forms (syrups, tablets, capsules, and slow
release forms), injections, and inhaled forms (metered dose inhalers, dry powder inhalers, and
solutions for nebulisation).
The best therapeutic effect is seen with the inhaled forms. The drug is used in very low doses, it
goes straight to the lungs, and the rest of the body has minimal exposure to the drug. Quick,
potent action, and low incidence of side effects.
Oral forms are also much used, though these drugs have unreliable absorption and action. The
incidence of side effects like a fats heart rate, tremor, and vomiting is also much greater. The
slow release forms offer the advantage of prolonged duration of action, but must be swallowed
whole, a task possible only for older children.
Once upon a time, no prescription for asthma was complete without this drug. It is available as
oral forms (syrup, tablets, and slow release forms) and injectable form. There is no inhalation
preparation. The oral forms are erratically absorbed, their effect is much less and slower than the
inhaled short acting beta agonists, and the side effects are many, making blood level testing
necessary. Not surprisingly, these drugs are almost never used today in the management of acute
asthma, though they still have a role in long term management of asthma.
The injectable form of theophylline was much used in intravenous drips for the treatment of
acute severe asthma. Now, however, its use has been replaced by nebulised salbutamol,
terbutaline, and ipratropium.
These drugs act by inhibition of the cholinergic nerves, and so reverse some airway narrowing.
Not effective enough to be used alone, but useful when added to inhaled short acting beta
agonists for the management of acute, severe asthma. The only drug of this class in use today is
Ipratropium bromide, which is available as metered dose inhalers and as a solution for use with
nebulisers.
The old favourite. It's an effective drug, but has to be given by injection, and is associated with
side effects like tachycardia (a fast heart rate) and hypertension (high blood pressure). Has been
largely forgotten after the advent of inhaled beta agonists.
Steroids are dangerous. Steroids save lives.
An incongruous pair of statements, but both true. Oral and injected steroids (which affect the
whole body, and are therefore called systemic steroids, in contrast to the inhaled steroids which
affect the lungs only, and are called local steroids) are very potent drugs, and like other such,
can do both great good and great harm.
In severe, acute asthma, there is significant inflammation in the wall of the airways, and surface
acting inhaled steroids are inadequate to the task of reversing it. Oral steroids must be used to
bring the airway inflammation and hyperresponsiveness under control. The two drugs used for
this are hydrocortisone (injectable) and prednisolone (oral).
It usually needs only a few days of systemic steroid therapy to control the asthma, and thereafter
the drug can be stopped abruptly, while the child is then put on a controller drug regime. Used
with restraint and skill, and for short courses, systemic steroids are safe and effective, rapidly
controlling the asthma, hastening recovery, relieving symptoms, and sometimes helping the child
to avoid hospitalisation.
Steroids take a significant time to reach the peak of their action, and ongoing beta agonist
therapy must be continued. The advantage of hydrocortisone and prednisolone are that they are
quickly eliminated from the body. Steroids like dexamethasone and betamethasone have slow and long
lasting actions, and are not suitable for children. As with all medical treatment, the severity of the disease and the distress of the child must be balanced against the potential harms of the drug.
Last revision: July 15, 2007
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