Nortriptyline and Ziprasidone: interaction and safety

Interaction mechanism

Ziprasidone combined with another established QT-prolonging drug can increase the risk of a serious rhythm disturbance. Nortriptyline may increase the sedative effects of other CNS depressants. Tricyclic antidepressant and neuroleptic co-treatment carries class warnings about metabolic interactions and a lower seizure threshold. Combining medicines that delay cardiac repolarisation may increase the risk of ventricular arrhythmia. Centrally acting medicines may increase drowsiness and problems with attention or coordination. Other serotonergic medicines can increase serotonin-syndrome risk during ziprasidone treatment.

Clinical significance and safety

Nortriptyline and Ziprasidone: Ziprasidone combined with another established QT-prolonging drug can increase the risk of a serious rhythm disturbance. Nortriptyline may increase the sedative effects of other CNS depressants. Tricyclic antidepressant and neuroleptic co-treatment carries class warnings about metabolic interactions and a lower seizure threshold. Combining medicines that delay cardiac repolarisation may increase the risk of ventricular arrhythmia. Centrally acting medicines may increase drowsiness and problems with attention or coordination. Other serotonergic medicines can increase serotonin-syndrome risk during ziprasidone treatment. Drowsiness, dizziness, reduced coordination and falls can be more likely. Driving and other hazardous tasks require particular caution when affected. The class warning does not mean that every combination is contraindicated or that each pair has been tested in a separate clinical trial. The ziprasidone label advises avoiding other established QT-prolonging drugs. Heart disease, a slow pulse and low potassium or magnesium can increase concern. A clinician determines whether ECG or electrolyte checks are needed. Fainting or new irregular palpitations require urgent assessment. Concurrent antipsychotic treatment or a planned switch requires specialist review of movement symptoms, alertness, balance and cardiac risk. A class precaution is not evidence that all such combinations are absolutely contraindicated. Urgent assessment is needed for a new combination of agitation or confusion, fever, marked sweating, tremor or abnormal muscle movements. The warning does not provide a pair-specific incidence or establish that toxicity is inevitable.

Using this information

This is a source-based reference record, not a recommendation to combine, stop or change medicines. A missing interaction record does not establish safe use. A qualified healthcare professional should consider the exact products, doses, other medicines and individual health circumstances.