Asthma medication
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Asthma medication is designed to reverse the constriction of bronchi that causes the difficulty in breathing in asthma.
So called "anti-asthmatic drugs" can be categorised as: relievers, symptom controllers and preventers, depending on their method of action and duration.
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[edit] Relievers
Asthma relievers such as salbutamol (Ventolin) or terbutaline are designed to quickly dilate the smooth muscle of the bronchi, enabling air to flow more freely. They normally come in a blue inhaler.
They are selective β2 agonists, working on adrenergic receptors mostly in the lungs. (These are the same receptors adrenaline works on, except adrenaline has more effects on other tissues such as the heart.)
Many of the side effects of β2 agonists are caused by their actions on other tissues, and can potentially cause tremors and tachycardia (fast heart rate). This is because the drugs have a small actions on other receptors, and also because there are a few β2 receptors in the heart.
These are inhaled if breathing becomes difficult. The best way to take them is to have one puff, then wait a minute, and then have another puff. Doing this allows the larger airways to dilate, letting the drug get through to the smaller airways on the second puff.[citation needed]
With chronic use, the airways of the lungs get slightly desensitised to the actions of these preventers.[citation needed]
[edit] Symptom controllers
Symptom controllers are long acting β2 agonists. They are similar in structure to the relievers, but have much longer sidechains. Examples include salmeterol, formoterol and bambuterol.
[edit] Preventers
Asthma preventers are the corticosteroids, that can be inhaled or taken orally, and work by altering the production of chemicals that cause the asthmatic response.
There are many corticosteroids around, such as beclomethasone, budesonide, fluticasone, dexamethasone and prednisolone. They are often in brown-coloured inhalers, and are marketed with names such as Becotide, Flixotide, and Pulmicort.
Long-term use of corticosteroids can have many side effects. Corticosteroids can cause a redistribution of fat, increased appetite, blood glucose problems, and weight gain. They also cause thinning of the skin, osteoporosis, decreased immunity and slower healing.
Because of these side effects, the dose of corticosteroid should be minimised. For this reason inhaled steroids should be used for prevention, as they are more targeted to the lungs than oral preparations.
When using inhaled corticosteroids, (or anything drug from an inhaler), even with the best technique, most gets deposited in the mouth and does not reach the lungs. The corticosteroids can then cause a hoarse voice or oral thrush (due to decreased immunity). The chance of these side effects can be minimised by rinsing the mouth with water after inhaler use, as well as by using a spacer which increases the amount of drug that reaches the lungs.
The frequency of use should be minimised. For example, four puffs twice a day is better than two puffs four times a day.[citation needed]
