What to give a patient with hypertension who had a seizure due to hyponatremia and is on Losartan (angiotensin II receptor antagonist)?

Management of Hypertension in a Patient with Seizure Due to Hyponatremia on Losartan

For a patient with hypertension who had a seizure due to hyponatremia and is currently on losartan, you should discontinue losartan and switch to a calcium channel blocker or beta-blocker for hypertension management while correcting the hyponatremia.

Understanding the Problem

Losartan, an angiotensin receptor blocker (ARB), can contribute to hyponatremia through several mechanisms:

• ARBs like losartan can increase the risk of hyperkalemia when used with other medications affecting potassium levels 1
• ARBs may worsen hyponatremia, particularly in susceptible patients
• The patient has already experienced a severe complication (seizure) from hyponatremia, indicating urgent intervention is needed

Management Algorithm

1. Immediate Management of Hyponatremia-Induced Seizure

• If seizure is ongoing: Administer benzodiazepines (e.g., diazepam) to stop the seizure 2
• For severe symptomatic hyponatremia with seizures:
  • Administer 3% hypertonic saline to raise serum sodium by 4-6 mEq/L within 1-2 hours 3
  • Target correction rate: no more than 8 mEq/L in 24 hours for chronic hyponatremia to prevent osmotic demyelination syndrome 4
  • Once seizures are controlled, slow the correction rate

2. Discontinue Losartan

• Immediately stop losartan as it may be contributing to the hyponatremia
• ARBs can increase the risk of hyponatremia, especially when combined with other medications 4

3. Alternative Antihypertensive Selection

• First choice: Calcium channel blocker (e.g., amlodipine)

  • Does not significantly affect sodium levels
  • Effective blood pressure control
  • Can be used in patients with electrolyte disorders

• Alternative: Beta-blocker (e.g., metoprolol)

  • Consider if no contraindications exist (asthma, severe bradycardia) 4
  • Provides effective blood pressure control without affecting sodium balance

4. Ongoing Hyponatremia Management

• For moderate hyponatremia (120-125 mEq/L):

  • Fluid restriction to 1,000 mL/day 4
  • Monitor serum sodium levels every 4-6 hours initially

• For severe hyponatremia (<120 mEq/L):

  • More severe fluid restriction
  • Consider albumin infusion 4
  • Avoid overly rapid correction (keep <8 mEq/L per 24 hours) 4

Special Considerations

Monitoring Requirements

• Serum sodium: Check every 4-6 hours initially, then daily until stable
• Serum potassium: Monitor closely, especially during transition from losartan
• Blood pressure: Monitor frequently during medication changes
• Neurological status: Assess for signs of osmotic demyelination syndrome (confusion, dysarthria, dysphagia, parkinsonism)

Pitfalls to Avoid

1. Overly rapid correction of hyponatremia: Can lead to osmotic demyelination syndrome, which can cause permanent neurological damage 4
2. Restarting ARBs too soon: Do not restart losartan until sodium levels have normalized and the cause of hyponatremia is fully addressed
3. Inadequate monitoring: Failure to closely monitor electrolytes during treatment can lead to complications
4. Overlooking the underlying cause: Investigate and treat the primary cause of hyponatremia beyond just stopping losartan

Long-term Management

• Once sodium levels normalize, maintain on calcium channel blocker or beta-blocker
• Consider periodic monitoring of serum sodium levels
• Educate patient about symptoms of hyponatremia and when to seek medical attention
• Avoid reintroduction of medications that may cause or worsen hyponatremia

By following this approach, you can effectively manage the patient's hypertension while addressing the serious complication of hyponatremia-induced seizure and preventing its recurrence.