Steroids Flashcards
What does the term respiratory disease mean?
Term given to diseases that affect organs and tissues involved in gaseous exchange.
What does the upper respiratory tract consist of?
Pharynx, nose and nasal cavity.
What does the lower respiratory tract consist of?
Larynx, trachea, bronchi and lungs.
What are steroids, what are their function?
Steroids are natural and synthetic compounds.
Have important physiological role in body for cell signaling.
Function as anti-inflammatory agents.
Describe steroid structure.
Characterised by 4 cycloalkane rings - 3 cyclohexane and 1 cyclopentane.
Variation obtained by different functional groups and oxidation state of rings.
Describe why endogenous steroids have an important biological role.
They’re present in lipid membranes.
Facilitates membrane fluidity (temperature dependent).
Controls membrane permeability
What is steroidogenesis?
Biological process by which endogenous steroids are generated from cholesterol.
Define hormone.
chemical messenger released by a cell/gland in one part of the body that can affect cells in another part of the body.
Where are corticosteroids produced? What are their functions?
(Includes glucocorticoids (cortisol) and mineralocorticoids (aldosterone))
Produced in the adrenal cortex.
Regulate immune function, stress response and metabolism.
Where are sex steroids produced? What are their functions?
Includes androgens (testosterone), oestrogens (estradiol) and progestogens (progesterone)
Produced by ovaries, testes and adrenal gland.
Interact with estrogen and androgen receptors.
Differentiate sex and supports reproduction.
Steroids decrease inflammation and activity of the immune system. In 2 simple sentences describe why.
Reduce production of inflammatory mediators (cytokines).
Alter the functioning of immune cells.
In asthma, there is inflammation of the airways and constriction of smooth muscle. How do steroids help with this?
Reduce inflammation and swelling in airways to restore airflow and to alleviate pressures in breathing
Give an example of a widely used anti-inflammatory drug.
Dexamethasone.
What conditions is dexamethasone used for?
Arthritis, cancer, colitis, allergies, asthma.
What is the MOA of dexamethasone?
Reduce vasodilation and permeability of blood vessels.
Regulates gene expression.
Dampens activation of immune system.
Stops pro-inflammatory cascade.
There is no benefit in using dexamethasone in less severe disease of COVID-19. Why does dexamethasone work best in severe patients?
Severe patients are on ventilation and given oxygen. Mechanical ventilation causes stress within body and stress upregulates expression of ACE2 - this allows entry of virus into the cell. Dexamethasone blocks this pathway, preventing increase in ACE2.
ACE2 = angiotensin converting enzyme 2.
What is the general MOA of steroids? All steroids function the same way. Talk about interaction to entry into nucleus.
Steroid cross the plasma membrane and interacts with a steroid receptor.
Binding to receptor displaces a protein called chaperone e.g. HSO90.
Chaperone protein will keep receptor in correct place and facilitate receptor functioning.
Steroid-receptor complex then forms a dimer and enter nucleus of cell.
Name 5 steroid drugs. Give type of formulation and route of administration.
Fluticasone propionate - inhaler - inhalation
Beclomethasone dipropionate - inhaler - inhalation
Budesonide - inhaler - inhalation
Prednisolone - tablet - oral
Hydrocortisone - injection - IV
