Risk of SIADH with Quetiapine (Seroquel)
Quetiapine can cause Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH), though it is considered a rare adverse effect that is documented in the FDA drug label as a post-marketing reported event. 1
Evidence for Quetiapine-Induced SIADH
The FDA drug label for quetiapine specifically lists SIADH among the adverse reactions reported during post-marketing surveillance. These reactions were temporally related to quetiapine therapy, though the exact frequency cannot be reliably estimated due to voluntary reporting from a population of uncertain size 1.
Case reports in the medical literature have documented instances of quetiapine-induced SIADH:
- A 65-year-old female patient treated with quetiapine for schizophrenia who presented with generalized tonic-clonic seizures was diagnosed with quetiapine-induced SIADH 2
- A 45-year-old man with paranoid schizophrenia developed hyponatremia due to SIADH repeatedly after treatment with both haloperidol and quetiapine 3
Risk Factors and Monitoring
Several factors increase the risk of developing medication-induced SIADH:
- Age: Older patients are at higher risk 3
- Comorbid conditions: Certain medical conditions predispose to SIADH
- Polypharmacy: Multiple medications increase risk 3
- Concomitant medications: Other psychotropic drugs may have additive effects
Clinical Implications and Management
Monitoring Recommendations
- Monitor serum sodium levels during the first 2-4 weeks of quetiapine therapy, particularly in high-risk patients 3
- Be vigilant for early symptoms of hyponatremia, which may include:
- General weakness
- Confusion
- Headache
- Nausea
- In severe cases: seizures and coma 4
Management of Quetiapine-Induced SIADH
If SIADH is suspected:
- Discontinue quetiapine if possible or consider alternative antipsychotic with lower SIADH risk 4
- Implement fluid restriction (1,000-1,500 mL/day) 4
- Monitor sodium levels closely during treatment
- For severe symptomatic cases: Consider 3% hypertonic saline with careful monitoring to avoid overly rapid correction 4
Alternative Antipsychotics
If a patient develops SIADH on quetiapine, consider switching to an alternative antipsychotic. In one case report, a patient who developed SIADH with both haloperidol and quetiapine did not experience this adverse effect when switched to clozapine 3.
Conclusion
While SIADH is a recognized but rare adverse effect of quetiapine, clinicians should maintain awareness of this potential complication, especially in high-risk patients. Regular monitoring of serum sodium levels during the initial weeks of treatment is advisable for patients at increased risk of developing electrolyte disorders.