Can I take Losartan (angiotensin II receptor antagonist) if I have seizures due to hyponatremia?

Losartan Use in Patients with Seizures Due to Hyponatremia

Losartan should be avoided in patients with a history of seizures due to hyponatremia as it can potentially worsen hyponatremia and trigger seizures. 1

Mechanism and Risk

Losartan, an angiotensin II receptor antagonist (ARB), has been documented to cause hyponatremia in some patients. A case report demonstrated severe hyponatremia (sodium level of 123 mEq/L) developing after 3.5 months of losartan therapy, with symptoms including drowsiness and severe generalized weakness 1. Similarly, other medications affecting the renin-angiotensin-aldosterone system, such as lisinopril (an ACE inhibitor), have been associated with severe symptomatic hyponatremia leading to seizures with serum sodium as low as 101 mEq/L 2.

Hyponatremia and Seizure Risk

Hyponatremia is a serious electrolyte disorder that can lead to significant neurological complications:

• Mild symptoms include nausea, vomiting, weakness, headache, and mild neurocognitive deficits 3
• Severe symptoms include delirium, confusion, impaired consciousness, ataxia, and seizures 3
• Acute hyponatremia (developing in <48 hours) is more likely to cause symptoms than chronic hyponatremia 4
• Seizures are particularly common when sodium levels fall rapidly or reach levels below 125 mEq/L 5

Management Considerations

For patients with a history of hyponatremia-induced seizures who require antihypertensive therapy:

1. Alternative Antihypertensive Options:

   • Consider antihypertensive medications less likely to cause electrolyte disturbances
   • Calcium channel blockers or beta-blockers may be safer alternatives

2. Monitoring Requirements if ARBs Must Be Used:

   • Regular monitoring of serum sodium levels (before initiation and periodically during treatment)
   • More frequent monitoring in patients with risk factors for hyponatremia
   • Immediate discontinuation if sodium levels begin to decrease

3. Risk Factors for Medication-Induced Hyponatremia:

   • Advanced age
   • Female gender
   • Concomitant use of other medications that can cause hyponatremia
   • History of hyponatremia
   • Renal impairment

Clinical Approach for Seizures Related to Hyponatremia

If a patient presents with seizures potentially related to hyponatremia:

• Immediate measurement of serum sodium is critical 6
• Patients with sodium concentration <125 mEq/L and severe symptoms require emergency infusions with 3% hypertonic saline 3
• Using calculators to guide fluid replacement helps avoid overly rapid correction of sodium, which can cause osmotic demyelination syndrome 3
• Correction should not exceed 15 mEq/L in 24 hours to prevent central pontine myelinolysis 5

Special Considerations

In patients with a history of seizures from any cause, medication selection should carefully weigh risks and benefits. The American Heart Association/American Stroke Association guidelines note that seizures can be independently associated with worse outcomes in certain conditions 6. Therefore, medications that might lower the seizure threshold or worsen the underlying cause of seizures should be avoided when possible.

For patients with hyponatremia-induced seizures specifically, addressing the underlying cause of hyponatremia is paramount, and introducing medications that could potentially exacerbate this condition creates unnecessary risk.

Conclusion

Given the documented cases of losartan-induced hyponatremia 1 and the serious neurological consequences of hyponatremia including seizures 3, 5, losartan should be avoided in patients with a history of seizures due to hyponatremia. Alternative antihypertensive medications with lower risk of affecting sodium levels should be considered instead.