Can Rexulti or Qelbree Cause Hyponatremia?
Based on available evidence, there is no documented association between Rexulti (brexpiprazole) or Qelbree (viloxazine) and hyponatremia. The provided guidelines and research focus on well-established causes of drug-induced hyponatremia, and neither medication appears in these comprehensive reviews.
Evidence Review
Established Drug Classes That Cause Hyponatremia
The medical literature identifies specific drug classes with documented hyponatremia risk 1, 2, 3:
- Diuretics (particularly thiazides) - most common cause 1, 2, 3
- Antidepressants (SSRIs, SNRIs, tricyclics) 1, 2, 3
- Antiepileptics (carbamazepine, oxcarbazepine, valproate, levetiracetam, phenytoin) 4
- Antipsychotics (traditional agents) 1, 2
- Proton pump inhibitors (omeprazole, pantoprazole) 5
Absence of Evidence for Rexulti and Qelbree
Neither brexpiprazole (Rexulti) nor viloxazine (Qelbree) is mentioned in comprehensive reviews of drug-induced hyponatremia 1, 2, 3. The 2024 ADHD guidelines specifically addressing viloxazine (Qelbree) do not list hyponatremia as a known adverse effect, though they acknowledge limited safety data overall 6.
Clinical Implications
For Rexulti (Brexpiprazole)
- This atypical antipsychotic is not documented as causing hyponatremia in the reviewed literature
- Traditional antipsychotics are known causes 1, 2, but newer atypical agents like brexpiprazole lack specific documentation of this adverse effect
For Qelbree (Viloxazine)
- The 2024 ADHD guidelines note there are no published studies on viloxazine safety in pregnancy or breastfeeding 6, indicating limited overall safety data
- Hyponatremia is not mentioned among known adverse effects in available guideline discussions 6
- The medication is relatively new with limited post-marketing surveillance data
Monitoring Recommendations
If prescribing either medication to patients at baseline risk for hyponatremia, monitor serum sodium levels based on general principles rather than drug-specific concerns:
- Elderly patients (age-related risk) 3
- Patients on concurrent medications known to cause hyponatremia (diuretics, SSRIs, carbamazepine) 1, 2, 4
- Patients with conditions predisposing to hyponatremia (cirrhosis, heart failure, SIADH) 6
Check baseline and periodic sodium levels in high-risk patients, as hyponatremia from any cause can be asymptomatic initially 1, 3.
Important Caveats
- Absence of evidence is not evidence of absence - both medications have limited long-term safety data
- Post-marketing surveillance may reveal adverse effects not identified in clinical trials
- Any new neuropsychiatric symptoms in patients on these medications warrant electrolyte evaluation 3