Moderate
Amitriptyline × Quetiapine
Tricyclic antidepressants (TCA)×Atypical antipsychotics
Mechanism
Additive anticholinergic and QT effects. Both are sedating and orthostatically active. In older patients, cumulative anticholinergic burden raises delirium risk.
Symptoms
Dry mouth, constipation, urinary retention, accommodation disturbance, tachycardia. In older patients: delirium and confusion risk. Postural dizziness, syncope, fatigue. Older patients: fall and fracture risk. Pronounced morning sedation possible.
Management
Avoid in older patients — delirium and fall risk. In bipolar disorder with chronic pain, alternatives: lamotrigine (a non-sedating mood stabiliser) with gabapentin or pregabalin. If unavoidable (severe insomnia, migraine), begin both at minimum doses and check ECG at 2 weeks.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.