Aldosterone Antagonists Flashcards
Example
Spironolactone
Indications
- Hypertension
- Heart failure
- Primary hyperaldosteronism
- Hepatic failure with ascites
What is ascites?
- Abnormal fluid occumulation in the peritoneal cavity
What are the contraindications of spironolactone?
- Hyperkalaemia
- Hyponatraemia
- Addisons disease
Cautions
- Porphyria
- Renal impairment
- Hepatic impairment
- Pregnancy and breast feeding
What is porphyria?
- A disease in which porphyrins build up
- Affects skin or nervous system
How do aldosterone antagonists inhibit the actions of aldosterone?
- Prevent aldosterone binding to its receptor
What does the prevention of aldosterone from binding to its receptor cause?
- Reduced sodium reabsorption
- Causes loss of Na and water
- Reduces potassium excretion
Why is the diuretic effect of spironolactone weak?
- Only 2% or reabsorbed sodium done through aldosterone
What systemic effect will the reduction of aldosterone cause?
- Reduction in blood pressure
How is spironolactone administered?
- Oral
What adverse reactions can occur with spironolactone?
- Hyperkalaemia
- Gynaecomastia
- Impotence
- Menstrual irregularities
- Hepatotoxicity
What drugs does spironolactone interact with?
Those that increase potassium
- ACE-I
- Angiotensin II antagonists
- Potassium sparing diuretics
Use with these will cause hyperkalaemia (may also occur with NSAIDs)
What can spironolactone cause with relation to digoxin?
- Can increase plasma digoxin levels
What can spironolactone cause with regards to lithium
Can decrease lithium excretion leading to toxicity
