Symptoms
- presented with signs and symptoms of hyponatremia (eg, nausea, malaise, headache, lethargy, seizures, coma, respiratory depression)
- decreased serum sodium levels (101-109 mEq/L)
ACE Inhibitors
- Frequency is unreported
- ACE inhibitors alone can precipitate hyponatremia without co-administration of thiazide diuretics
- hyponatremia induced by ACE inhibitors appears to be dilutional and is accompanied by features of SIADH
- discontinuing the ACE inhibitor leads to resolution of the hyponatremia
- Patients may show hypokalaemia if thiazide or loop diuretics are used concomitantly with ACE inhibitors
Mechanism & Risk
- It is postulated that ACE inhibitors at low doses cannot block the conversion of angiotensin I to angiotensin II in the brain. Increased circulating angiotensin I is converted to angiotensin II in the brain causing thirst stimulation and consequently SIADH.
- risk for hyponatremia may be greater in patients on concomitant diuretic therapy or who have congestive heart failure.
Calcium Channel Blockers
- In theory, calcium channel antagonists with natriuretic properties could cause hyponatremia.
- A case of amlodipine-associated hyponatremia has been reported.
- calcium channel antagonist– related hyponatremia, if it exists, is extremely rare.
Management
- In mild to moderate cases with a normovolaemic fluid status clinically, ceasing the offending drug and gentle fluid restriction would improve serum sodium levels gradually within a week.
- In an acutely unwell patient due to severe drug induced hyponatraemia, severe fluid restriction or infusion of hypertonic saline may be require
- May consider changing therapy and monitoring patient for improvement
Alternatives
- Diuretics are not recommended as have higher likelihood of causing hyponatremia
- ARBs are also established to cause hyponatremia and no available data on comparison with ACEi
- Beta Blockers- Beta blockade, especially of the Beta 1 receptor at the macula densa, inhibits renin release, & the release of aldosterone. This causes hyponatermia and hyperkalemia
References:
- http://www.gpnotebook.co.uk/simplepage.cfm?ID=x20120201092040500242
- https://www.pjms.com.pk/issues/aprjun207/article/casereport3.html
- Jenny A. Van Amburgh. Can Lisinopril Cause Hyponatremia? - Medscape - Jul 28, 2011
- American Journal of Kidney Diseases, Vol 52, No 1 (July), 2008: pp 144-153
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