Pharmacology Final

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Principle steroid with mineralocorticoid activity is

aldosterone
mineralocorticoid receptor binds aldosterone and cortisol with

equal affinity
Mineralocorticoids are critical in regulating

concentrations of minerals, mainly potassium and sodium in extracellular fluids
Loss of aldosterone hormones leads rapidly to

life threatening abnormalities in electrolye and fluid balance
Major target of aldosterone is in the ___ where it stimulates ___.

distal tubule of the kidney where it stimulates exchange of sodium and potassium
Primary physiologic effects of aldosterone
- increased resorption of sodium
- increased resorption of water
- increased renal excretion of potassium
two most significant regulators of aldosterone secretion
- increases in concentration of potassium ions in extracellular fluids
- angiotensin II
Other factors which stimulate aldosterone secretion
- adrenocorticotrophic hormone
- sodium deficiency
Factors which suppress aldosterone secretion
- atrial naturetic hormone
- high sodium concentrations
- potassium deficiency
A deficiency in aldosterone can occur in conjunction with

hypoadrenocorticism or addison's disease
A lack of aldosterone is lethal due to

electrolyte imbalances and resulting hypotension and cardiac failure
Fludrocortisone Acetate
- synthetic adrenocortical steroid
- high glucocorticoid activity
MoA of fludrocortisone
- similar to hydrocortisone
- binds mineralocorticoid receptor
- binding results in increases in ion and water transport and thus raises extracellular fluid volume and blood pressure
- potassium levels are lowered
Indication for fludrocortisone
- partial replacement therapy for adrenocortical insufficiency in Addison's disease
- treatment of salt-losing adrenogenital syndrome
Contraindications for fludrocortisone

pt with systemic fungal infections
Drug interactions with Fludrocortisone
- ampho B or potassium depleting diuretics
- digitalis (because of K+ changes)
- oral anticoagulants
- Anti-diabetic drugs
- CYP inducers increase secretion of fludrocortisone
Fludrocortisone toxicity
- irritation
- cardiac edema
- increased blood volume
- HTN
- effects on e- balance and carb metabolism are heigtened and prolonged b/c it is synthetic
Mineralocorticoid antagonist

spironolactone
Spironolactone MoA

synthetic steroid that acts as a competitive antagonist to aldosterone and prevents binding
Spironolactone metabolism
- extensive hepatic metabolism
- not good for pt with hepatic damage
Spironolactone kinetics
- slow onset of action
- requires several days to achieve therapeutic effect
Clinical indications for spironolactone
- mineralcorticoid excess due to hypersecretion
- conn's syndrome
- extopic ACTH production
Toxicity with spironolactone
- hyperkalemia
- kidney stones
- gynecomastia
- metabolic acidosis
- acute renal failure
Contraindications for spironolactone
- oral K+ administration
- impaired hepatic function
- Chronic renal insufficiency

Author

Rx2013

81941

Card Set

Pharmacology Final

Description

mineralocorticoids

Updated

2011-04-26T16:39:59Z

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