Imipramine hydrochloride

How it works

It inhibits reuptake of noradrenaline and serotonin and has antimuscarinic, antihistaminic and alpha-adrenergic blocking actions that account for much of its adverse-effect profile.

Prescribing in practice

• Tricyclics are dangerous in overdose with cardiotoxicity and arrhythmia, so assess suicide risk and consider quantities supplied, and avoid in recent myocardial infarction, arrhythmias and heart block.
• Antimuscarinic effects cause dry mouth, constipation, blurred vision and urinary retention, and it can cause postural hypotension and lower the seizure threshold.
• For childhood nocturnal enuresis follow a children's formulary, treat for a limited period with review, and counsel on overdose danger to household members.

Monitoring

Monitor mood and suicidality, cardiovascular status and antimuscarinic burden, with ECG consideration where cardiac risk is present.

Counselling the patient

• Store securely away from children, as overdose is dangerous.
• Expect dry mouth, constipation or blurred vision, and rise slowly to avoid dizziness.
• Do not stop abruptly; the dose should be reduced gradually under advice.

Evidence & guidelines

Tricyclic antidepressants such as imipramine are long-established treatments, and NICE depression guidance notes their toxicity in overdose relative to newer agents.