Drugs to treat asthma can be categorized into a few general drug groups. Members within each group are considered more or less interchangeable. Bronchodilators (drugs that relax the muscles around the airways) are generally the most frequently used drugs for asthma treatment. Bronchodilators can be inhaled, taken by mouth, or injected into the muscles or veins.
The following is a summary of common medications used in asthma treatment.
Beta2 Adrenoreceptor Agonists
- Drug group: Beta2 (ß2) adrenoreceptor agonists (adrenoreceptor refers to a site where adrenalin works)
- Common drugs: Common ß2 agonists include salbutamol (Ventolin®, Proventil®), terbutaline (Bricanyl®), rimiterol (Pulmadil®) and fenoterol (Duovent®).
- How they work: Adrenoreceptor agonists have the same effect as natural adrenalin: they help keep the airways open by relaxing the muscles in the walls of the airways. ß2 receptor agonists are normally inhaled and are used at irregular intervals and as a first line treatment.
- Possible side effects: Although ß2 agonists can be highly effective immediately (and for up to six hours) if taken in high dosage, they sometimes produce a “rebound” effect that can trigger an addtional attack. Also, ß2 agonists have no effect on inflammation.
Corticosteroids
- Drug group: Corticosteroids (steroid drugs)
- Common drugs: Common corticosteroids include prednisolone (Prednesol®) and methylprednisolone (Medrone®).
- How they work: Corticosteroids can be taken by mouth, inhaled, or injected. These drugs are highly effective in suppressing inflammation, and reducing mucus secretion.
- Possible side effects: Dosage must be monitored carefully by a physician. Some patients may experience suppression of the body’s
production of natural steroids, growth suppression, the likelihood of new infections, high blood pressure, exacerbation of stomach or duodenal ulcers, osteoporosis, diabetes, glaucoma, cataracts, and increased growth of body hair.
Anticholinergics
- Drug group: Anticholinergic drugs (ipratropium)
- Common drugs: Common anticholinergic drugs include Atrovent®, Combivent® and Duoneb®.
- How they work: Inhaled anticholinergic asthma drugs relax the airway muscles much like atropine (belladonna), but without the
unpleasant side effects to the nervous system. If a ß2 is followed by ipratropium, the two drugs tend to enhance each other’s effects. - Possible side effects: Not always effective in preventing the narrowing of airways in exercise and cold air-induced asthma.
Xanthine Derivatives
- Drug group: Xanthine derivatives
- Common drugs: Common xanthine derivative bronchodilators include theophylline (e.g. Choledyl®, Theo-Dur®) and theobromine.
- How they work: Theobromine has a similar (although lesser) effect to caffeine. Theophylline has a strong effect in widening the
airways. Its main action is to relax the muscles in the bronchi and improve efficiency of the diaphragm. - Possible side effects: Excessive doses of theophylline have been known to cause convulsions and in rare cases, brain damage. It is not recommended for people who are prone to panic disorders. Other possible side effects include heart irregularity, personality changes, hyperactivity, nausea and vomiting.
Sodium Cromoglycate Drugs
- Drug group: Sodium cromoglycate drugs
- Common drugs: Sodium cromoglycate is more commonly referred to as cromolyn (Intal®, Novo-cromolyn®).
- How they work: Taken by inhalation in aerosol solution or as a powder driven by a turbo inhaler, cromolyn works by preventing the
release of histamines into the airways. Sodium cromolglycates are particularly effective in the treatment of allergy-induced asthma. - Possible side effects: Although sodium cromoglycates don’t actually widen narrowed airways, they nevertheless help indirectly by preventing them from becoming narrower.