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Coronavirus & Dexamethasone

In this series of articles, medical students from across the country will share their knowledge of medical physiology, anatomy and biochemistry to give you a taster of medical school. This will be a fantastic opportunity to build upon your A-Level Knowledge.

Remember it's more important to understand the principles than to mindlessly memorise facts.

Patients who have been severely affected by Covid-19 may now benefit from doses of Dexamethasone, reducing the death toll and giving their families their loved ones back. Dexamethasone is a steroid drug – for treatment, patients are given 6 mg of dexamethasone over 10 days. This costs around £35 per patient, which is a sustainable cost. It can also be made worldwide as it is out of patent, allowing lives to be saved globally.

The steroid drug is only shown to have a significant effect in patients who are being ventilated or who are receiving oxygen:

Ventilated Patients

In a trial, 94 of the 324 (29%) patients taking dexamethasone died compared to 278 of the 683 (40.7%) not taking dexamethasone.
This is a reduction of about 1/3

Patients receiving Oxygen

In a trial, 275 of the 1279 (21.5%) taking dexamethasone died compared to 650 of the 2604 (25%) not taking dexamethasone.
This is a reduction of about 1/5.

Patients receiving no respiratory support

In a trial, 85 of the 501 (13.2%) taking dexamethasone died compared to 137 of the 1034 (17%) not taking dexamethasone.
This was not considered a significant enough difference for dexamethasone to be used for treatment in this group. Therefore, people who have tested positive have been recommended to not go and seek this medication out by themselves.

Mechanism of Action

Steroids are actually natural hormones originating from cholesterol and produced by the adrenal glands, which are endocrine glands that sit on top of the kidneys. Each part of the kidney produces a different steroid, each having different roles:

Zona glomerulosa - produces mineralocorticoids, which are used for salt and water balance
Zona fasciculata - produces glucocorticoids, which have many jobs including controlling how the body uses glucose and in the immune response.
Zona reticularis - produces androgens, the male sex hormone

Therefore, steroid drugs, which are termed corticosteroids, can often be given if the patient has an adrenal insufficiency, for example. However, this is not all that corticosteroid drugs are used for.

Dexamethasone is a corticosteroid that has a very high glucocorticoid activity and an insignificant mineralocorticoid activity. Glucocorticoids such as dexamethasone are powerful inhibitors of inflammatory processes as they inhibit inflammatory molecules such as cytokines. In coronavirus, there is a cytokine storm (excessive levels of cytokines) and thus dexamethasone can aid in the treatment of coronavirus.

Other common illnesses or conditions that dexamethasone is used to treat include:

· Allergic disorders

· Asthma

· Local inflammation

· Croup, another respiratory viral infection

Side Effects

However, using corticosteroids doesn’t come without its drawbacks. A common side effect of using corticosteroids is Cushing’s syndrome, which is the result of too many steroids in the body. Patients will often present with weight gain, facial rounding, proximal muscle weakness and thinning skin. They may also develop metabolic complications such as diabetes and a high blood pressure. This syndrome has a characteristic appearance which, as a medical student, you will become very much used to.