Corticosteroids Flashcards
What is a corticosteroid and what does it do?
Steroid that increases gluconeogenesis and increases fat redistribution
What is a mineralocorticoid and what does it do?
Steroid that helps the kidneys and colon with electrolyte and water balance
What is an example of naturally produced mineralocorticoid:
Aldosterone and Deoxycortisone
Do high anti-inflammatory, immunosuppressant activity and effects on carb and protein metabolism correlate more with glucocorticoid or mineralocorticoid activity?
Glucocorticoid activity
What is the predominant action of glucocorticoids on intermediary metabolism?
Increase the breakdown of proteins and lipids (gluconeogenesis)
T/F Corticosteroids also cause an increase in glycogenolysis
FALSE; they do not change glycogenolysis
What is the predominant action of corticosteroids on CNS?
Glucocorticoids: excitation and euphoria
Mineralocorticoids: decrease excitability by decreasing K in the ECF/ICF –> Hyperpolarization –> decreased excitability
What effects does glucocorticoids have on the lymphoid tissues and immune responses?
Increase PMNs, monocytes, and platelets, while decreasing lymphocytes, eosinophils, and basophils
Decreases the production of IL 1 and 2
Increases immunosuppresive cytokine production
What can the use of glucocorticoids lead to in regards to immune and lymphoid tissues/
Increases circulating RBC, neutrophils, and platelets
Decreases circulating lymphocytes, and basophils
Can also decrease size of LNs and thymus
Why would you use glucocorticoids in a lymphoid tissue setting?
Can supplement the treatment of lymphoma or mast cell tumors
Can be used to control excessive humoral or cellular reactions
Glucocorticoids can have what effect on RBCs?
Increases RBCs leading to polycythemia
Glucocorticoids have what effect on inflammatory processes?
Anti-inflammatory due to suppression of immune system
DOES NOT suppress the underlying issue
What effects do glucocorticoids have on skeletal muscle function? Mineralocorticoids?
Deficiency can cause weakness due to hypoglycemia and poor circulation
Excess M: hypokalemia which causes weakness in muscles
What effects do glucocorticoids have on electrolyte and water balance? Mineralocorticoids?
G: Incerase the cardiac output leads to increase GFR; after while can lead to PU/PD
M: Increase Na and HCO3 retention and increase H, Cl, and K excretion
What effects does glucocorticoids have on the respiratory tract?
Increases the expression of Beta-2: bronchodilation
Increase expresion of alpha-2: vasoconstriction
Helps with anti-inflammatory
What effects does M&G have on cardiovascular system?
Increases the vasomotor responses and myocardial contraction.
M: Increases Na in ECF = increased BP
M: Decreases K in ECF = increases myocardial Ca
G: increase the expression of A-adrenergic receptors in BVs and Beta-adrenergic receptors in heart
What are the clinical signs of hyperadrenocorticism? How do these relate to the actions of the steroids?
PU/PD: diurect effect from excretion of glucose and ions
Polyphagia: trying to eat more glucose so they don’t have to bkdown their body
Potbelly: weakness of abdominal muscles
Muscle weakness: breakdown of muscle
Recurrent UTI: Lots of glucose and ions in the urine for bacT and the immune system is suppressed
Dermatologic conditions: not enough energy to grow hair
What are the clinical signs of hypoadrenocorticism? How do these relate to the actions of the steroids?
Dehydrated: body isn’t retaining Na or glucose so water flows out of the body
Hypotension: dehydrated
Bradycardia: dehydrated
Renal failure: no aldosterone produced; losing Na and water –> medullary washout
Circulation collapse: dehydration
How does an animal get hyperadrenocorticism from steroid treatment?
Vet continually keeps the animal on steroid treatment
How does an animal get hypoadrenocorticism from steroid use?
Had them on corticosteroids, adrenal crotex atrophies, and then takes them off the corticosteroids
How does mineralocorticoid affect electrolyte transport in the kidney?
Increases Na and HCO3 and decreases K, H, and Cl in the distal tubules and collecting duct
Aldosterone increases Na absorption, which incrases AIP –> increases Na/K ATPase pump –> increased Na/ decreased K
Why would a mineralocorticoid such as DOC increase myocardial contractility?
Hypokalemia = increase in myocardial Ca = increased contractility
Why would you not use DOC with digoxin?
They essentially both do the same thing; Cardiac arrythmias
What are the genomic mechanism of actions for corticosteroids?
Increases mRNA synthesis for enzymes that breakdown bradykinin and enzymes for gluconeogenesis
Decreases mRNA synthesis of cytokines and their receptors
Inhibits expression of chemicals responsible for inflammation while expressing ones that are anti-inflammatiory
What are some examples of the nongenomic actions of corticosteroids/
BP and Hr can increase within 10 minutes
Activation of plasma membrane receptors or ion channels
Know key differences between Cortisol, DOC, and Dexamethasone and why that affects their activity
All has to do with carbon binding
Cortisol, dexmethasome, and DOC: discuss the structure activity relationship of these glucocorticoids
Cortisol: most prevalent GC in mammals
DOC: Loses both 11-OH and 17-OH = NO GC activity but good MC activity
Dexamethasone: CH3 on C16 to protect 17OH enhances GC activity
Rank the glucocorticoid potency in animals of: cortisone, cortisol, prednisolone, prednisone, methylprednisolone, fluoroprednisolone, dexamethasone, DOC, Aldosterone
Dex: (G=25) Fluoroprenisolone (G=20) Methylprednisolone (G=5) Prednisolone (G=4) Cortisol (G=1) Aldosterone (G=.3) DOC (G=0) Prednisone and cortisone (No activity)
Rank the mineralocorticoid activity of aldosterone, DOC, and cortisol
Aldosterone (M=3000)
DOC (M=100)
Cortisol (M=1)
What are some corticosteroids that are naturally produced by animals?
Cortisol, corticosterone
Would you want to administer these naturally occuring corticosteroids to animals? Why or why not?
NO; they are subject to 1st pass effect. Most of the drug will be deactivated and flushed out
Do corticosteroids cure disease and remove the underlying condition?
NO, they simply help with the symptoms and make the animal feel better
What is the advantage of alternate day therapy? What corticosteroids would be good for this use?
There is less atrophy of the pituitary gland because the drug is given less frequently
Prednisolon, triamcinolone
Why are Gs used as part of chemotherapy regimens? What kind of cancer patients would respond best to glucocorticoid tx? What are the adverse effects?
Used against lymphoma and mast cell tumors; apoptosis of lymphocytes and decreases size of LNs and thymus
Administration of exogenous glucocorticoids can cause the dog to have hyperadrenocorticism
If you need to administer an immediate acting glucocorticoid orally to cats or horses, would you use prednisone?
NO; conversion of prednisone to prednisolone is impaired in cats and horse
Which corticosteroid injectable preparations can be given in a safe manner?
Only water soluble forms: phosphate, succinate salts, or polyethylene glycol
DO NOT give IV suspensions = embolism
Which synthetic corticosteroid is the preferred drug for the control of hypoadrenocorticism? Why?
Fludrocortisone: high GC and MC activity
What are the two major types of adverse reactions associated with the corticosteroid therapy?
Iatrogenic hypoadrenocorticsim
Toxic effects (Extension of pharmacological effects)
Are the adverse effects of corticosteroids qualitatively different from the physiological and pharmacological actions of the compounds?
No they are usually just extension of the pharmacologic effects
List at least ten of the adverse effects of the corticosteroids
Decreased wound healing Increased susceptibility to infection Epidural steroid could induce pathogens Fluid and electrolyte imbalance Thrombosis Myopathy Osteoporosis Glaucoma
Why would the long-term use of glucocorticoid cause bone fracture?
Causes a negative Calcium imbalance. Increased PTH will increase osteoclastic activity to reabsorb bone
Apoptosis of osteoblasts will lead to decreased bone collagen synthesis and bone formation
Least at least 5 contraindications to the use of corticosteroids
Uncontrolled infections DM Corneal ulcers Cardiac disorders Burns Late pregnancy
Why should you not use glucocorticoids for the tx of corneal ulcers?
G will suppress the maintenance of corneal epithelium, which will cause perforation of cornea
Why should you be extra careful in selecting the dosages of GCs in birds, rodents, and cats?
Corticosterone is the endogenous corticosteroid of birds, rodents, and cats; 30% more potent than cortisol
Should use short acting, alternate day therapy. NEVER use long acting GC
Differentiate the effects of ACTH and an individual GC or MC
ACTH stimulates adrenal cortex to release corticosteroids; will get GC and MC actions both
Does not have specific effect
Why is ACTH not used therapeutically?
Half-life is so short and ACTH is not specific
Used more to diagnose
What is an adrenal cytotoxic agent?
Mitotane
Which zones of the adrenal cortex does Mitotane destroy?
Zona fasiculata and reticularis
Does not affect the Zona glomerulosa (aldosterone)
How do ketoconazole, trilostane, bromocriptine, and selegiline affect corticosteroid secretion?
ketoconazole: inhibits steroidogenesis by inactivating cytochrome P450
Selegiline: Inhibits ACTH secretion by increasing DA
Trilostane: inhibitor of 3Beta-hydroxysteroid dehydrogenase
Ketoconazole, trilostane, bromocriptine and selegiline; which can cause repro failures as a side effect?
Trilostane
Ketoconazole
What drug is best for treating hyperadrenocorticism?
Trilostane
What are some naturally occuring minarolcorticoids?
Aldosterone and DOC
