Question

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give me Overview of Pharmacokinetic Properties of (Dexamethasone & how it's related to COVID-19)

Answer 1

Dexamethasone serves as a glucocorticoid medication which is used to treat several conditions such as allergic reactions, chronic lung disorders, asthma and arthritis.

Upon oral administration, dexamethasone dissolves quickly in the blood and reaches a steady level within 1 hour. It binds to the glucocorticoid receptors, expressed on the surface of nerve cells whereby it inhibits the activity of hypothalamus. As a result, secretion of corticotrophin-releasing hormone (CRH) decreases. It also suppresses the secretion of adrenocorticotropic hormone (ACTH, released by anterior pituitary gland). Both CRH and ACTH are the major hormones which are known to synthesize and release cortisol (a stress hormone). However, when dexamethasone drug suppresses the synthesis of these hormones, the secretion of cortisol reduces rapidly. The effect of dexamethasone lasts for about 36 to 54 hours, it is metabolized in liver and is excreted via urine.

Recently, dexamethasone has been recommended for the treatment of patients suffering from COVID-19. During COVID-19 infection, body produces generous amount of cortisol which allows the release of cytokines to detroy this virus. However, cytokines also destroys body's own cells while fighting coronavirus. This results in the accumulation of fluid and cell debris inside the air sacs of lungs and causes breathing difficulties. This leads to the severe respiratory distress which can be fatal to the patient. When patients are administered with dexamethasone drug, the level of inflammatory cytokines are reduced rapidly. Dexamethasone binds to the cell receptors, thereby, suppresses the release of cortisol which further decreases the secretion of cytokines.