Corticosteroids Flashcards
Haematological effects of corticosteroids?
Reduce B and T cell levels in plasma
Increase peripheral neutrophil count
Reduce eosinophil, basophil, monotype and lymphocyte count by redistributing them from circulation into lymphoid tissue.
Increase levels of haemoglobin, erythrocytes, platelets and polymorphonuclear lymphocytes
What is the benefit of synthetic corticosteroids?
Some have a longer half life
What is prednisone to prednisolone?
Its prodrug
Intracellular steroid mechanism steps?
Forms receptor hormone complex
Enters nucleus
Attaches to gene promoter elements
Acts as a transcription factor to turn genes on and off depending on the tissue
What is a characteristic of the effect of corticosteroid produced by the intracellular mechanism?
It takes time to produce an effect
Mechanism of the anti inflammatory effects of glucocorticoids?
Lowers circulation lymphocytes
Inhibit phospholipase A2 which reduces the production of both leukotrienes and prostaglandins
Stabilising mast cell and basophil membranes thereby reducing histamine release
Name a mineralocorticoid
Fludrocortisone
How can RDS be prevented in premature infants?
Betamethasone or dexamethasone administered to the mother within the 48 hours preceding delivery.
Steroids accelerate lung maturation
Which corticosteroid is preferred in pregnancy?
Prednisone as it is not converted to prednisolone in the foetal liver
How long does it take for large doses of corticosteroids to cause HPA suppression?
More than two weeks
Name the anti steroids
Ketoconazole
Spironolactone and eplerenone
Aminoglutethimide
Metyrapone
How does ketoconazole work?
Selectively inhibits steroids synthesis
How does metyrapone work?
Inhibits synthesis of steroids
How does eplerenone work?
It is an aldosterone antagonist at the mineralocorticoid receptor
Describe the interpretation of the dexamethasone suppression test
In normal patients the result is always suppression
In pituitary adenoma only the high dose will suppress
In an ACTH tumour there will not be suppression
