dexamethasone
Dexamethasone is used for immune suppression in a range of diseases and disorders such as:
dermatitis, eczema, asthma, leukaemia, emphysema, arthritis, rheumatic fever and COVID-19.
Steroids
Dexamethasone is an analogue of the steroid hormone, cortisol. This means that it has a very similar chemical structure and that they are able to bind to similar proteins in the body.
Hormones are chemicals found naturally in our body that are used to send messages from one part of the body to another. They travel in the blood stream and are known as signalling molecules.
Steroid hormones have a specific core 4-ring system (shown to the right) within their chemical structure. They regulate our metabolism, immune system, inflammation, sexual characteristics and even the salt and water balance in our cells. Steroid hormones are able to cross cell membranes passively (through diffusion).
Can you spot the similarities and differences between dexamethasone and cortisol below?
dexamethasone
cortisol
How Does it work?
Dexamethasone is particularly important for regulating inflammation a key issue in a number of autoimmune diseases.
When a harmful substance enters our body, our immune system jumps into action, attacking cells which have become infected. Inflammation is one of processes the immune system uses to defend your cells. You might have notice some of the signs of inflammation; redness, swelling, heat and pain, when you have been ill or injured. While our immune system helps protect us, if it is not regulated it can over-react and start attacking healthy cells.
As a mimic of the natural signalling molecule cortisol dexamethasone can bind to cortisol's receptor, the glucocorticoid receptor. When bound to this receptor, it starts a cascade of processes in the body with results in the production of anti-inflammatory proteins. In this way dexamethasone can reduce inflammation by suppressing the immune systems when it over-reacts.
Did you know: Inflammation plays a key role in many autoimmune diseases including lupus and rheumatoid arthritis.
What do you think is a benefit of having a medicine like dexamethasone that treats a range of conditions on the Essential Medicines list?