Aldosterone Antagonists
Examples
- Spironolactone
- Eplerenone
Indications
- Heart failure (adjunct)
- Primary hyperaldosteronism
- Hepatic failure with ascites
- Oedema in congestive heart failure
Contraindications
Contraindications
- Hyperkalaemia
- Addison's disease
Caution
- Porphyria
- Acute or severe renal impairment
- Hepatic impairment
- Pregnancy and breast feeding
- Hyponatraemia
Mechanism
Aldosterone antagonists inhibit the actions of aldosterone by preventing the binding of aldosterone to its receptor. In this way it reduces the reabsorption of sodium, causing loss of sodium and water, and decreasing potassium excretion. The diuretic effect is weak due to the fact that only 2% of sodium reabsorption is controlled by aldosterone. Reduction in Aldosterone will reduce blood pressure.
Administration
Oral
Adverse Reactions
- Hyperkalaemia, particularly in combination with other agents
- Gynaecomastia
- Impotence
- Menstrual irregularities
- Hepatotoxicity
Interactions
Other drugs which increase potassium, such as ACE inhibitors, Angiotensin II antagonists and other potassium sparing diuretics, will have an additive effect to the hyperkalaemia induced by aldosterone antagonists. This may also occur with NSAIDs.
Spironolactone can increase plasma Digoxin levels.
Spironolactone can decrease Lithium excretion.
Aldosterone antagonists should not be prescribed with potassium supplements.
Education
Advise patients of the seriousness of raised potassium and the importance of attending regular blood tests.
Pharmacokinetics
No specific issues.
