adrenocorticosteroids Flashcards
describe the hormonal steroids..
- glucocorticoids - effects on intermediary metabolism and immune function
- mineralocorticoids - principally salt-retaining activity
- steroids c androgenic and estrogenic activity
describe the layers of adrenal glands..
capsule
adrenal cortex
zona glomerulosa - mineralocorticoids, mainly aldosterone
zona fasciculata - glucocoricoids, mainly cortisol
zona reticularis - androgens
adrenal medulla - chromaffin cells secrete Epi and NE
glucocorticoid agonists?
prednisone hydrocortisone dexamethasone beclomethasone triamcinolone methylprednisolone
minderalocorticoid agonists?
aldosterone
fludrocortisone
glucocorticoid antagonists?
mifepristone
mineralocorticoid antagonists?
spironolactone
drugs that cause hormonal synthesis inhibition?
ketoconazole
aminoglutethimide
metyrapone
describe cortisol (hydrocortisone)
circadian rhythm and stress stimulate hypothalamus to release CRH -> act on the anterior pituitary to release ACTH -> act on the adrenal cortex -> release cortisol -> tissue responses (physiological/metabolic effects)
cortisol has negative feedback to the hypothalamus and anterior pituitary.
secretion and synthesis tightly regulated by CNS
Cortisol (hydrocortisone)
MOA?
- effects mediated by widely distributed glucocorticoid receptors.
- steroid-receptor complex enters the nucleus and interacts c promoters of (and regulates the transcription of) target genes
- produce tissue-specific responses
Cortisol (hydrocortisone)
Metabolic effects?
- stimulates and is required for gluconeogenesis & glycogen synthesis (which maintains hepatic glycogen avail) in fasting state
- -> increase serum glucose levels (thus leading to stimulation of insulin release) & inhibiting uptake by muscle cells.
- stimulates lipolysis (leading to fat deposition and redistribution & increased release of fatty acids & glycerol)
- stimulates protein catabolism & release of amino acids
NET result: maintenance of an adequate glucose supply to brain (most apparent in fasting state)
Cortisol (hydrocortisone)
Catabolic effects?
- in addition to protein catabolism, cortisol also has effects in lymphoid and connective tissue, muscle, peripheral fat and skin (wasting occurs at high conc).
- catabolic effects on bone = osteoporosis
- in children = growth retardation
Both are major limitations in long term tx c glucocorticoids.
Cortisol (hydrocortisone)
Immunosuppressive effects?
effects on leukocytes:
- increased neutrophils (increased influx into blood & decreased migration from blood vessels)
- decreased lymphocytes (T and B cells), monocytes, eosinophils and basophils (movement from vascular bed to lymphoid tissue)
vasoconstriction due possibly to suppression of mast cell degranulation
- decreased histamine release and capillary permeability
Cortisol (hydrocortisone)
Anti-inflammatory effects?
- inhibit PLA2 (through induction & activation of annexin I) which blocks arachidonic acid release (major precursor for PG)
- cyclooxygenase-2 synthesis is reduced (through inhibition of NF-kappB)
- induction of MAPK phophatase I (inhibits MAPK activated proinflammatory signaling pathways).
Cortisol (hydrocortisone)
other effects?
CNS: behavioral changes (insomnia, euphoria -> depression)
Increased ICP: large doses
Suppression of release of ACTH, GH, TSH, LH: chronic use
Peptic ulcers: stimulation of gastric acid. Suppression of immune response to H. pylori?
increase platelets & RBCs
Renal function: impaired c cortisol deficiency
Devel of fetal lungs.
Cortisol (hydrocortisone)
Pharmacokinetics?
short duration of action
diffuses poorly across skin (unless inflamed)
diffuses well across mucous membranes
some salt-retaining effects
prednisone, methylprednisolone, dexamethasone, beclometahsone, triamcinolone
PK?
prednisone = prodrug (rapidly converted to active prednisolone)
Beclomethasone = short t1/2, penetrates airway mucosa (low systemic toxicity)