Zuclopenthixol (Clopixol) — oral, acuphase, and depot

Zuclopenthixol, marketed as Clopixol by Lundbeck, is a thioxanthene antipsychotic developed in Denmark and approved in many countries since the 1970s. It is one of the antipsychotics with the widest range of formulations — oral tablets and oral drops for daily use, a short-acting Clopixol Acuphase intramuscular injection (zuclopenthixol acetate) for acute behavioural disturbance, and a long-acting Clopixol Depot (zuclopenthixol decanoate) for maintenance. It has never been approved by the US FDA but is widely used in the UK, the rest of Europe, Canada, Australia, and many other countries.

How it works

Zuclopenthixol blocks dopamine D1 and D2 receptors, with broad effects on serotonin, histamine, and alpha-1 adrenergic receptors. It is moderately sedating and has notable anticholinergic and orthostatic effects compared with high-potency typicals like haloperidol.

The three formulations

Oral zuclopenthixol

Tablets and oral drops, taken daily. Per international product information (e.g., the UK eMC labelling), typical adult doses for schizophrenia are 20 to 60 mg per day in divided doses, occasionally higher in inpatient settings. Older adults are started at much lower doses.

Clopixol Acuphase (zuclopenthixol acetate)

A short-acting intramuscular injection used in some countries for the initial management of acute psychosis or severe behavioural disturbance. The acetate ester releases zuclopenthixol over 2 to 3 days, providing extended sedation and antipsychotic effect from a single injection. Typical doses are 50 to 150 mg, with a maximum total course usually of 400 mg or 4 injections over 2 weeks. Acuphase is not a long-term maintenance treatment — it is a bridge to oral or depot treatment.

Acuphase has been controversial. The Cochrane Schizophrenia Group has reviewed its evidence base multiple times and concluded that the available trials are limited and do not clearly show advantages over standard care. UK NICE guidance on rapid tranquillisation (NG10) does not endorse Acuphase as first-line. Where it is used, it is in settings with experienced clinicians and careful monitoring.

Clopixol Depot (zuclopenthixol decanoate)

A long-acting intramuscular injection given every 2 to 4 weeks for maintenance treatment of schizophrenia. Typical doses are 200 to 500 mg every 2 to 4 weeks, with adjustments based on response and tolerability. Some patients are stable on lower doses, particularly older adults.

Indications

Across the three formulations, zuclopenthixol is used for:

• Schizophrenia and other psychotic disorders
• Acute mania (in some labels)
• Initial management of acute psychotic episodes (Acuphase, in some countries)
• Maintenance treatment to support adherence (depot)

Side effects

Sedation

Substantial, particularly with Acuphase. Many patients are markedly drowsy after a dose.

Movement effects

Acute dystonia, parkinsonism, and akathisia are common. The risk is higher with depot than with oral because dose adjustments are slow. Anticholinergic medications are often co-prescribed. Tardive dyskinesia risk accumulates over years.

Anticholinergic and orthostatic

Dry mouth, constipation, urinary retention, blurred vision, dizziness on standing — moderate, less than chlorpromazine but more than haloperidol.

Weight gain and metabolic effects

Modest to moderate. Less than olanzapine or clozapine, more than haloperidol.

Cardiovascular

QT prolongation possible. Orthostatic hypotension common, particularly during initiation.

Hyperprolactinemia

Substantial.

Injection site reactions

For depot and Acuphase: pain, redness, induration. Deep gluteal injection technique and site rotation help.

Boxed warnings (international)

International labels generally include the antipsychotic warning about increased mortality in elderly patients with dementia-related psychosis. QT prolongation, EPS, NMS, and tardive dyskinesia warnings are also standard.

Drug interactions

Additive sedation with CNS depressants. Additive QT effects with other QT-prolonging drugs. Lowered seizure threshold. Always disclose all medications and supplements.

Where zuclopenthixol fits today

In countries where it is available, zuclopenthixol is used:

• As maintenance treatment in patients with severe schizophrenia, particularly via depot
• For inpatient management of severe behavioural disturbance (Acuphase, where local protocols permit)
• In patients who have done well historically
• As a generic option in cost-constrained settings

In the US, the closest equivalents are haloperidol decanoate, fluphenazine decanoate, or a second-generation depot for maintenance.

For patients moving between countries

Patients on zuclopenthixol who move to the US will need to transition to an antipsychotic available there. The cross-titration is best planned with a prescriber experienced in depot conversions. Conversely, patients moving to the UK, Canada, or Europe may find zuclopenthixol available as an additional option.

Practical questions to ask

• Which formulation am I being prescribed and why?
• What is the plan for monitoring movement side effects?
• Should I be on an anticholinergic?
• What is the injection schedule, and what should I do if I miss one?
• What is the plan if Acuphase needs to be repeated?

The big picture

Zuclopenthixol is one of the most flexible antipsychotics outside the US — three formulations, decades of clinical experience, generic availability. The Acuphase formulation in particular has a controversial evidence base and is used cautiously in many systems. The depot has a clear maintenance role for patients with adherence challenges. As always, the question of fit is best worked out with a prescriber who knows your history and the local context.

This article is for educational purposes only and is not medical advice. Information is summarised from publicly available FDA labelling, regulatory sources, and peer-reviewed literature. Always consult your prescribing clinician before starting, stopping, or changing any medication.