corticosteroids Flashcards
what stimulates the zona glomerulosa to produce Aldosterone
Angiotensin II & K+
what stimulates the zona fasciculata & what does it produce
ACTH
cortisol
what does the zona reticularis produce
Adrenal androgens
what are cortisol & aldosterone released from
Adrenal cortex
what stimulates the release of Cortisol & aldosterone from the adrenal cortex
ACTH
what does aldosterone do
increases Na and H20 retention
increases K+ excretion
Glucocorticoids are anti- ?
inflammatory
how do glucocorticoids counter the effect of insulin
- increase circulating amino acids
- increase circulating fatty acids
- increases gluconeogenesis
what is the effect of glucocorticoids on thyroid hormones
decreases TSH and therefore decreases thyroid hormone
what is the affect of glucocorticoids on ACTH
decreases ACTH via negative feedback on CRH
what is the number one cause of hypoadrenocorticism (Addison’s)
autoimmune disorder
what are the causes of hypoadrenocorticism
- Primary autoimmune disorder (90%)
- iatrogenic
- neoplastic (pituitary tumor destroys ACTH production)
- breed predisposition
gradual process that presents acutely - signs become apparent with 90% loss of adrenal cortex
hypoadrenocorticism
signs are vague: poor BCS, weight loss, lethargy
severe signs of hypoadrenocorticism
- Bradycardia
- hypovolemic shock
- anemia
how do Na, K, Cl levels present in a hypoadrenocorticism patient
- hyperkalemia
- hyponatremia
- hypochloremia
glucocorticoid absorbed poorly in feline and equines
prednisone
glucocorticoids are _____ soluble & therefore are distributed widely
lipid
glucocorticoids are bound in plasma by ______ & ________
albumin and corticosteroid binding globulin
prednisone & cortisone are both ?
prodrugs
prednisone –> prednisolone
cortisone –> hydrocortisone
prednisone and cortisone are bad choices for what patients and why
prednisone - cats b/c can’t metabolize
animals in liver failure won’t metabolize either drug
how are glucocorticoids useful in the treatment of osteoarthritis
they reduce production of PGE2 by synoviocytes and chondrocytes & suppress production of IL-1 and TNF-alpha all of which contribute to cartilage breakdown
triamcinolone
labeled for use in horses
(musculoskeletal/joint inj)
isoflupredone
labeled for use in swine & cows
(musculoskeletal/joint inj)
flumethasone
labeled for use in horses & dogs
(musculoskeletal/joint inj)
methylprednisolone & betamethasone
ELU
(musculoskeletal/joint inj)
adverse effects of…
- triamcinolone
- isoflupredone
- flumethasone
- methylprednisolone and betamethasone
- muscle atrophy (increases circling amino acids)
- osteoporosis (increases Ca excretion annd inhibits osteoblast function)
- inhibits fibrocartilage growth (don’t use in growing animals)
what are the major reasons to NOT USE glucocorticoids in treatment of integument conditions
- cutaneous food allergies
- infectious or parasitic (bacteria/fungal infections, flea allergy dermatitis)
*
what drug is used for the treatment of IBS
Prednisolone
what are the drug options for treatment of bovine ketosis
both: induce gluconeogenesis
* dexamethasone (abortant)
* isoflupredone (may cause hypokalemia, less risk for abortion)
what are the causes of hyperadrenocorticism (mostly dogs)
- pituitary tumors (85%)
- adrenocortical tumors (15%)
- iatrogenic (glucocorticoids)
effect of glucocorticoids on the cardiovascular system
vasoconstriction b/c increased sensitivity to sympathetic stimulation
hypervolemia due to aldosterone causing retention of Na and H2O
Hypervolemia –> increased BP, compensatory decrease in ADH secretion, dilute urine, PU/PD
Glucocorticoids antagonize insulin, leading to ?
hyperglycemia; increases gluconeogenesis
effects of glucocorticoids on circulating fatty acids
increases circulating FAs, leads to fat redistribution that contributes to thin skin and potbelly
why can hyperadrenocorticism cause gastric ulcers and colonic perforation
decreased PLA2 causes a reduction in prostagladin production, prostaglandin helps maintian mucous integrity
under what cicumstances can hyperadrenocorticism lead to adrenal atrophy
only with iatrogenic hyperadrenocorticism
Cosyntropin
ACTH stimulation test
(peaks effects occur at 30 min for hoses, 60 min for dogs)
hyperadrenocorticism would cause an above average spike in serum cortisol levels post Cosyntropin admin
how can iatrogenic hyperadrenocorticism be confirmed
no response to the cosyntropin ACTH stimulation test confirms adrenal insufficiency and iatrogenic hyperadrenocorticism
what is the low dose dexamethasone suppression test
**Dexamethasone suppresses ACTH and CRH si it should reduce circulating cortisol **
measured at 4 and 8hrs post admin
if cortisol levels are still high at hour 8 –> hyperadrenocorticism
what is the drug of choice for small animal hyperadrenocorticism
Trilostane
what is the MOA of trilostane
competitive inhibitor of 3β-hydroxysteroid dehydrogenase
reduces but doesn’t eliminate the synthesis of corticosteroids
what are the adverse effects of Trilostane
- hypocortisolemia - lethargy, anorexia
- hyponatremia
- GI upset (D/V+)
- adrenal gland necrosis (super rare)
drug that destroys the zona reticularis and fasciculata but doesn’t reduce mineralcorticoid production
Mitotane
Equine cushings disease (PPID) cause
tumor in pars intermedia causes pressure atrophy of dopaminergic neurons in the hypothalamus
reduces inhibition of ACTH release = cortisol release
treatment for PPID in horses
Pergolide mesylate
highly potent dopamine receptor agonist
what are the to go home corticosteroids (4 to go home)
- Pred
- Methylpred
- Triamcinolone
- Fludrocortisone
Emergency corticosteroids (IV admin)
- Pred
- methylpred
- dexamethasone
what is the strongest mineralcorticoid
Fludrocortisone
what is the strongest glucocorticoid
dexamethasone
what mineralcorticoid has the longest duration
Deoxy pivilate (IM)
one month!
what corticosteroids are glucocorticoids only
- Triamcinolone
- Dexamethasone
what corticosteroids are mineralcorticoids only
- deoxy pivilate
- aldosterone
