Asthma Treatment

I’ll continue my quick dip into the technicalities of asthma this week by looking at asthma medicines. Obviously the easiest (and not to mention cheapest) method of preventing asthma attacks is to reduce contact with the antigen you react to. However this is only probably possible with antigens such as animal fur or cigarette smoke. For anything else some sort a medication is required. Asthma drugs fall into two types: short term relievers and long-term preventers. I’m on one of each. For people with mild asthma or who only have rare attacks a simple reliever is enough. For people with more than two attacks a week some sort of long term preventer is needed to manage the symptoms.

  

A Salbutamol molecule

Sort acting beta₂-adrenoceptor agonists (SABA’s) such as salbutamol (brand name ventolin) are the commonest form of asthma relief. They usually take effect after about 10 minutes and last about 6 hours. The drugs act on a receptor on the cell surface membrane of the muscles of the bronchi of the lungs. This relaxes the muscles so the airways widen and the symptoms are relieved.  Beta2-antagonists are good because they usually only effect the lungs unlike non-specific beta-agonists such as the older drug ephedrine which affected similar receptors in the heart causing tachycardia (the heart beating too fast) and arrhythmias (the heart beating irregularly). SABA’s are usually inhaled from a simple inhaler (or in a hospital a more powerful nebuliser) so the drug is delivered straight to the lungs. In very serious case in can be given intravenously.

  

Long-term prevention of attacks is done by a different set of drugs. I use Symbicort (brand name) which is a mixture of the chemicals budesonide and formoterol. The formoterol part is simply another drug to relax the bronchi muscles but a little long lasting. Budesonide is a glucocorticoid. I’ll just unpack that term piece by piece. Glucocorticoid (comes from glucose+cortex+steroid) is type of steroid hormone. A steroid is a molecule with four alkane rings (such as cholesterol and testosterone) and therefore tend to look like quite cool molecules. A hormone is a molecule released by a gland to effect cell elsewhere in the body. Glucocorticoids bind to a receptor present in most animal cells and are part of the body’s feedback loop that turns down immune system and inflammatory activity. This means they are used to treat diseases caused by an over active immune system such as asthma. Unfortunately they have various other effects so aren’t sold over the counter.

A Budesonide molecule

 Other drugs used to prevent symptoms are long-acting beta-adrenoreceptor agonist (LABA’s) and mast cell stabilizers.