Corticosteroids Flashcards
What are the 2 subgroups of corticosteroids?
mineralocorticoids Glucocorticoids
What are the major endogenous glucocorticoids? Where are they produced
cortisol Cortisone Corticosterone -Produced in the zona fasiculata of the adrenal cortex
Are the endogenous glucocorticoids produced at a constituative or enduced rate?
constitutive rate
What is the major mineralocorticoid?
aldosterone Produced in the zona glomerulosa Corticosterone converts to aldosterone
What regulates corticosteroid synthesis? Include the pathway for cortisol production
Hypothalamic-pituitary adrenal axis - stress elicits neurologic signals that activate the hypothalamus - Hypothalamus releases CRH which causes the anterior pituitary to release ACTH -ACTH stimulates cortisol synthesis
Cortisol synthesis from ACTH
- ACTH activates its receptor in the adrenals Activated ACTH-R initiates cAMP driven events resulting in: 1) receptor mediated uptake of LDL 2) Hydrolysis of cholesterol esters 3) Cholesterol transport into mitochondria 4) Synthesis of progenolone from cholesterol 5) synthesis of cortisol from pregnenolone
ACTH to aldosteronse pathway
ACTH-R initiates cAMP driven events resulting: 1) receptor mediated uptake of LDL 2) Hydrolysis of cholesterol esters 3) Cholesterol transport into mitochondria 4) Synthesis of prognenolone from cholesterol 5) synthesis of corticosterone from prognenolone 6) Synthesis of aldosterone from corticosterone in the zona glomerulosa cells
What feedback mechanisms are associated with ACTH?
ACTH inhibits its own release from the anterior pituitary. The activated ACTH-R initiates biochemical cascades and gene expression events resulting in the retention of ACTH
How does Cortisol have feedback on the HPA?
Cortisol inhibits CRH synthesis at the hypothalamus Cortisol inhibits ACTH release from the AP
Corticosteroids are agonists or antagonists for the cortisol receptor?
Agonists for the cortisol receptor
What is a side effect for prolonged corticosteroid drug usage
Adrenal atrophy
What can happen with abrupt withdrawal of a corticosteroid?
Can lead to adrenal insufficiency
Regulation of Aldosterone release?
ACTH Promotes the synthesis of aldosterone in the zona glomerulosa where aldosterone synthetase is present. the release of Aldosterone requires the presence of Angiotensin II
What is transcortin?
A plasma proteint that specifically carries corticosteroids to target organs. - carries exogenous and endogenous corticosteroids
Can Corticosteroids interact with their receptor while bound to Transcortin?
no- must be released from the transcortin
How is affinity and onset of action associated with transcortin
The affinity of a drug for transcortin will determine: - The onset of action - The duration of action
How are corticosteroids metabolized?
Transcortin influences hepatic metabolism of corticosteroids. it is not metabolized while bound to transcortin
Receptor selectivity and Physiologic functions of corticosteroids
- All endogenous glucocorticoids and all exogenous glucocorticoids have different affinities for the cortisol receptor. - Aldosterone has its own receptor that it is highly selective for. - some glucocorticoids can bind to and activate the aldosterone receptor. ***Kidney cells have an enzyme that inactivates cortisol thus preventing it from activating the aldosterone receptor
What are reasons for using corticosteroids?
Inhibit inflammation Suppress the immune system Replacement therapies
How do corticosteroids inhibit inflammation?
Reduce inflammation by activating the expression of lipocortin which is a direct inhibitor of PLA2 The inhibition of inflammation results from a reduction of capillary permeability and exudation
How do corticosteroids suppress the immune system
- suppress inflammation by inhibiting various aspects of cell mediated immunity such as T-cell associated cytokine production and signaling - Corticosteroids also promote the production of macrophage-associated cytokines that are antiinflammatory
Do NSAIDS suppress the immune system?
No, they are inhibitors of inflammation at the level of decreasing vascular permeability. Same for anti-histamines.
What are examples of primary conditions where corticosteroid replacement therapy is indicated?
Adrenal atrophy Cellular dysfunction Autoimmune disease Lack of normal secretion of corticosteroids
What are examples of secondary conditions where corticosteroid replacement therapy is indicated?
Pituitary issues - atrophy - dysfunction - auto immune lack of normal ACTH
What are examples of tertiary conditions where corticosteroid replacement therapy is indicated?
hypothalmic issues - atrophy - dysfunction - Autoimmune disease Lack of normal secretion of CRH
What reason would you have for short term use of corticosteroids?
shock
What reason would you have for chronic but finite/sporadic use of corticosteroids?
pruritic dermatoses (most common use) allergic respiratory and GI diseases
What reasons would you ahve for a chronic life-long use:
Autoimmune diseases Replacement therapy
Would you use corticosteroids for corneal ulcers?
no!!! makes them way worse
What ophthalmic inflammatory conditions may indicate use of corticosteroids?
retinitis choroiditis Optic neuritis
What neurologic conditions indicate the use of corticosteroids?
cervical or lumbar disc disease Vestibular disease Peripheral neuropathies Polymyositis