Chlorprothixene: First-Generation Antipsychotic with Sedative Properties
Chlorprothixene (Truxal) is a first-generation (typical) antipsychotic of the thioxanthene class. It blocks D2 dopamine receptors and has antihistaminic and anticholinergic properties, producing marked sedation.
Used primarily for acute agitation, anxiety with psychotic features, and as adjunctive sedation in psychiatric emergencies. Lower antipsychotic potency than haloperidol but more sedative.
Mechanism of Action
D2 receptor blockade reduces dopaminergic transmission (antipsychotic effect). Strong H1 antihistamine effect causes sedation. Anticholinergic and alpha-1 blocking properties contribute to additional side effects.
Indications & Use
Acute agitation and anxiety in psychotic disorders, short-term management of severe anxiety, adjunctive sedation in palliative care. Also used as a sleep aid in low doses in some European countries.
Dosage
Oral: 15–50 mg 3× daily (up to 300–600 mg/day for psychosis). Sedation/sleep: 15–50 mg at night. Elderly: start 15 mg, use lowest effective dose. IM formulation available for acute agitation.
Side Effects
Common: sedation, dry mouth, constipation, urinary retention (anticholinergic). EPS (less than haloperidol). QT prolongation — ECG monitoring recommended at high doses. Weight gain. Tardive dyskinesia with long-term use.
Drug Interactions
CNS depressants (alcohol, benzodiazepines, opioids): additive sedation. QT-prolonging drugs: additive risk. Anticholinergics: additive effects. Levodopa: antagonism (avoid in Parkinson's).
Contraindications
Comatose states, acute alcohol/barbiturate intoxication, Parkinson's disease, phaeochromocytoma, known QT prolongation. Caution in prostatic hypertrophy, glaucoma, cardiovascular disease.
Frequently Asked Questions
How does chlorprothixene compare to haloperidol?
Chlorprothixene is a low-potency typical antipsychotic — more sedating but less potent at D2 receptors than haloperidol. It causes more anticholinergic effects and less EPS than haloperidol, but carries similar long-term tardive dyskinesia risk.
Can chlorprothixene be used for sleep?
Yes, in low doses (15–50 mg) it is used as a sedative-hypnotic, particularly in patients with comorbid anxiety or agitation. Long-term use carries risks of dependence and tardive dyskinesia.
Is chlorprothixene still widely used?
Less so in current practice. Newer atypical antipsychotics with better tolerability profiles (less EPS, lower tardive dyskinesia risk) are preferred. Chlorprothixene may still be used for acute agitation or in palliative settings.
References
- Stahl SM: Stahl's Essential Psychopharmacology, 5th ed.
- Leucht S et al. Lancet 2013
- EMA Truxal SPC
Medical Disclaimer: This information is for educational purposes only and does not replace professional medical advice.