Trimipramine

How it works

It inhibits reuptake of noradrenaline and serotonin and has marked antagonism at histamine H1, muscarinic and alpha-adrenergic receptors, accounting for its sedative and antimuscarinic profile.

Prescribing in practice

• Tricyclic antidepressants are dangerous in overdose, causing cardiac arrhythmias, seizures and coma, so the risk should be assessed in patients at risk of self-harm.
• Antimuscarinic effects and postural hypotension are common, warranting caution in cardiac disease, glaucoma, prostatic hypertrophy and the elderly.
• It lowers the seizure threshold and should be used with caution in epilepsy, avoiding abrupt withdrawal.

Monitoring

Monitor mood and suicidal ideation, cardiovascular status and antimuscarinic side effects, particularly when initiating or adjusting treatment.

Counselling the patient

• This medicine is sedating and may cause drowsiness; avoid driving until you know how it affects you.
• Dry mouth, blurred vision and constipation are common, especially at first.
• It can be very dangerous in overdose, so take only as prescribed and seek advice before stopping.

Evidence & guidelines

The overdose toxicity of tricyclic antidepressants such as trimipramine is well documented and reflected in NICE depression guidance.