Asthma Medicines and how they work

Although some medicines are essential, it is important to remember that they are not the only part of asthma treatment (see leaflet "Allergy and Asthma"). Asthma medicines act be preventing or controlling asthma, so people with asthma must take these medicines every day, even when they are well - just like people with high blood pressure or epilepsy or diabetes have to take their medicine every day to stay well. There are two types of drugs used in the treatment of asthma - preventers and relievers. There is no connection between the effects of preventer and reliever drugs. They do separate things.

Preventers

• Preventers build up a protective shield in the linings of the breathing tubes (call airways or bronchi) and thereby stop or reduce swelling, mucus build-up and muscle tightening in your airways caused by the triggers of asthma.
• They will not work unless used regularly, so must be taken every day even when you are well.
• They do not bring any relief from symptoms (see Relievers below)
• They take about 14 days to build up the protective shield. You will therefore not see an immediate effect but after 1-2 weeks they will make a big difference in the amount of asthma symptoms you have
• There are two families of preventers:

  Steroids - inhaled and oral

  Cromolyns

• Preventers available in South Africa are listed below. Drug names beginning with a capital letter are their trade names (the ones you will see in shops), and the ones beginning with a smaller letter refer to their chemical names (used by chemists and doctors).

Steroids

• Steroids are a wide range of chemicals made both by the body and artificially.
• One group of steroids, the corticosteroids, are used to treat asthma.
• Corticosteroids are different from the antibiotic steroids taken by some athletes. Anabolic steroids are not used to treat asthma.
• They are the strongest inhaled preventers.
• They are used for moderate and severe asthma.
• Your doctor should advise you whether to decrease or increase the dose you are taking, or stop these medicines where possible. Do not adjust your doses without your doctor's advice.
• When inhaled they are usually used twice daily.
• They can be taken in 3 ways:

  inhaled (breathing them into the lungs),

  swallowed, either tablets or syrup

  injected for acute, severe asthma.

Inhaled steroids

• Inhalation is the preferred route because:
  

  The drug goes straight to the site where it acts, the lungs.

  The smallest dose possible is used which results in fewer side-effects.

• Side-effects are uncommon, but can be:
  

  hoarse voice or oral thrust, both of which can be prevented by mouth rinsing with water after inhalation.

  growth suppression (only when taken in high doses).

• Side-effects are reduced if a spacer is used, so if you are using a high dose, it is advisable to use a spacer.
• Children can take up to 400 micrograms per day (mcg/day) and teenagers up to 1500 mcg/day without fear of any side-effects.

Short-term (course) oral steroids

• Are available as a syrup or as tablets.
• Usually given to relieve an acute attack of asthma.
• They are used when inhaled steroids fail to control symptoms adequately.
• Usually given for 7-10 days.
• Many patients will keep such a course at home which can be used when their asthma worsens, as shown by increasing symptoms, especially at night or with exercise, or by a fall in their peak flow rate.
• When taking oral steroids some people notice an increase in appetite and slight weight gain.

Long-term oral steroids

• A small group of asthmatics need to take low dose oral steroids on a long-term basis because their symptoms continue to be significant and their asthma uncontrolled, despite high doses of inhaled steroids.
• This is becoming less common with the improvements in inhaled steroid therapy.

Injecting steroids

• Steroids can be injected only by a doctor or nurse.
• They are usually only used to treat acute, severe asthma when the patient cannot swallow the oral steroids.

Cromolyns

• Used in people with moderate asthma.
• Has mild side-effects of irritation of the throat, coughing, hoarseness, dry mouth, nausea and vomiting.
• Your child should continue his treatment even if feeling well.
• Symptoms may not be relieved initially and 2 weeks of continuous treatment may be needed for maximal effect to develop.
• Children seem to respond better than adults.
• This medicine may be taken as powder inhaler (spincaps), nebuliser solution or by aerosol.
• Tilade is non licensed for use in children, over 6 years of age and is similar to Lomudal.

Relievers

• One of the major causes of cough, wheeze or tight chest that asthmatics experience is bronchospasm which is tightening of the muscle around the airways (see What is asthma?).
• Bronchospasm is relieved by medicines called bronchodilators or relievers which help open the airways and make breathing easier.
• Relievers produce nearly instant relief and for this reason are used as 'first aid' treatment for asthma symptoms or attacks. Always carry them with you!
• Relievers have no effect on the swelling in the airways or the build up of mucous.
• Relievers are used only when the person with asthma has symptoms. If you need to use a reliever more than 3 times a week you should also be on a preventer.
• Some asthmatics need to use relievers before exercise even though their asthma is well controlled by preventers.
• Shakiness and a fast heart beat can occur when reliever medicines are first used, or when larger than normal doses are used. These effects disappear once the medicines have been used for a few weeks.
• Reliever medicines are available in three forms: inhalants, tablets or syrups.

Inhaled bronchodilators

• Inhaled medicines are preferred as they go directly and rapidly to the airways allowing smaller doses than oral medicines to be used
• Inhaler or spacer devices allow us to use asthma pumps in children of all ages.
• There are two types of inhaled bronchodilators:

  short-acting beta-agonists

  long-acting beta-agonists

• Short-acting beta-agonists are the reliever medicines already described
• Long-acting beta-agonists have a duration of action of 12 hours and are used for troublesome night-time and activity (exercise) induced symptoms. They are always used with preventer medicines.
  Oral bronchodilators
  
• They are available as syrups, tablets or capsules.
• They take longer than inhaled bronchodilators to work as they have to go the 'long way round' before they act on the lungs.
• There are two types of oral bronchodilators:

  beta-agonists

  theophyllines

Oral beta-agonists

• Because higher strengths have to be used than inhaled beta-agonists, side effects such as shakiness, headache, sleeplessness and simply a nervous feeling often occur.

Theophyllines

• There are two groups of theophyllines:

  short-acting - duration of action 4-6 hours

  long-acting - duration of about 12 hours

• Rectally administered theophyllines can be potentially dangerous and are not recommended.
• Over the last few years these medicines have been prescribed less frequently, mainly because they commonly produce side-effects such as:
  

  stomach upset, indigestion, heartburn, loss of appetite, nausea and vomiting.

  headache, sleeplessness, excited or nervous feeling and palpitations.

• Long-acting theophyllines are started in low doses and are used once or twice a day.
• Your doctor will send you for a blood test to measure the level of theophylline in the blood to determine the correct dosage.

Other medicines

• Homeopathic medicines are not commonly recommended for asthma. If you do wish to use these please do not stop your child's usual asthma medicines as prescribed by your doctor.
• Antihistamines can be used for other allergic conditions such as hay fever but are not considered to be standard asthma medicines.
• Antibiotics are rarely necessary as viral infections are by far the most common triggers of asthma attacks. The decision to use or not to use them will rest with the attending doctor.
• Cough mixtures offer no benefit in asthma management as the cough is most often a sign of poor asthma control needing relieving medicines.
• Tranquilisers are dangerous as they may suppress the breathing process especially in severe asthma attacks.
• Desensitisation is not recommended as asthma treatment as it is not effective and can be potentially dangerous.
• Ionisers are ineffective.

5 key points to remember

Preventers

• Inhaled steroids are the most effective preventer medicines.
• Inhaled steroids are safe at doses used most commonly.
• Spacers reduce the risk of side effects.
• Tablets may need to be used in a short course for an asthma attack.
• Steroids used in asthma are not anabolic steroids used by athletes.

Relievers

• Relievers are a measure of how well your asthma is being controlled. If you need relievers regularly it means you are not getting enough preventer medicine.
• Short-acting beta-agonists should only be used when asthma symptoms appear or before exercise.
• Inhaled short-acting beta-agonists act very quickly to relieve symptoms.
• Long-acting beta-agonists are used for troublesome night-time and exercise induced symptoms.
• Theophyllines are uncommonly used because of side-effects.

Written by: Dr Sam Risenga, Dr Bhadrish Vallabh, Dr Des Cohen, Dr Archie Mhlambi