Moderate
Bisoprolol × Quetiapine
Selective beta-adrenergic blockers×Atypical antipsychotics
Mechanism
Additive hypotension (quetiapine blocks α1-adrenoceptors) and additive bradycardia.
Symptoms
Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.
Management
The combination is acceptable at low quetiapine doses (≤300 mg/day). Check pulse and blood pressure 1–2 weeks after start. In older patients, olanzapine or aripiprazole (less α1-blockade) is preferable.