Haloperidol decanoate

How it works

It is an esterified prodrug that is slowly hydrolysed to release haloperidol, a potent antagonist at central dopamine D2 receptors in mesolimbic and other pathways.

Prescribing in practice

• Carries a high risk of extrapyramidal side effects and QT-interval prolongation, and may cause neuroleptic malignant syndrome; tardive dyskinesia can occur with long-term use.
• Patients should be stabilised and tolerate oral haloperidol before conversion to the depot, which is given at regular intervals by deep intramuscular injection only.
• Use with caution in the elderly, particularly those with dementia, owing to increased risk of stroke and death, and in cardiac disease.

Monitoring

Monitor for extrapyramidal symptoms, signs of tardive dyskinesia and neuroleptic malignant syndrome, and obtain ECG and serum potassium given the risk of QT prolongation.

Counselling the patient

• Explain that the injection is long-acting and effects persist for weeks after each dose.
• Report any abnormal movements, muscle stiffness, high fever or fainting promptly.
• Avoid abrupt discontinuation and attend regular review appointments.

Evidence & guidelines

Haloperidol is a long-established antipsychotic whose efficacy and adverse-effect profile, including the MHRA warning on antipsychotics and stroke risk in dementia, are well documented.