ATC Code N05AF03
Formula C18H18ClNS
Molar Mass (g·mol−1) 315,86
Physical State solid
Melting Point (°C) 97,5
CAS Number 113-59-7
PUB Number 667467
Drugbank ID DB01239
Solubility moderate in water / poor in ethanol


Chlorprothixene is a typical antipsychotic from the group of thioxanthenes. The main indications of chlorprothixene are the treatment of psychotic disorders (e.g. schizophrenia) and acute mania in the context of bipolar disorders. Other indications include pre- and postoperative states of anxiety and insomnia, severe nausea/vomiting (in hospitalized patients), improvement of anxiety and agitation due to the use of selective serotonin reuptake inhibitors in depression, and, off-label, for the improvement of alcohol and opioid withdrawal.



Chlorprothixene blocks postsynaptic dopaminergic D1 and D2 receptors and, with weaker affinity, serotonin histamine and adrenergic receptors, in the brain. Thus it has sedative, antipsychotic and antidepressant effects. Furthermore, it suppresses the release of hypothalamic and pituitary hormones and is thought to suppress the reticular activating system, thereby affecting basal metabolic rate, body temperature, wakefulness, vasomotor tone, and vomiting.


The half-life is approximately 8 hours.

Drug Interactions

  • Chlorprothixene may increase plasma levels of concomitantly administered lithium.
  • When chlorprothixene is administered concomitantly with opioids, the opioid dose should be reduced (by approximately 50%) because chlorprothixene significantly potentiates the therapeutic effects and side effects of opioids.
  • The concomitant use of chlorprothixene and tramadol should be avoided. Seizures may occur with this combination.
  • Additive sedative effects and confusional states are to be expected when chlorprothixene is given together with benzodiazepines or barbiturates.
  • Particular caution should be exercised when chlorprothixene is combined with other anticholinergic drugs (tricyclic antidepressants and antiparkinsonian agents): delirium, high fever, severe constipation up to ileus and glaucoma may occur, especially in the elderly.


Side effects

Chlorprothixene has a strong sedative effect with a high incidence of anticholinergic side effects.

Possible side effects:

  • Dry mouth
  • massive hypotension
  • tachycardia
  • hyperhidrosis
  • significant weight gain
  • severe constipation
  • difficulty urinating
  • confusion
  • constipation

Toxicological data

LD50 (rat, oral): 200 mg-kg-1


  • Drugbank
  • PubChem
  • Aktories, Förstermann, Hofmann, Starke: Allgemeine und spezielle Pharmakologie und Toxikologie, Elsvier, 2017
Markus Falkenstätter

Markus Falkenstätter

Markus Falkenstätter ist Autor zu pharmazeutischen Themen in der Medizin-Redaktion von Medikamio. Er befindet sich im letzten Semester seines Pharmaziestudiums an der Universität Wien und liebt das wissenschaftliche Arbeiten im Bereich der Naturwissenschaften.

Mag. pharm Stefanie Lehenauer

Mag. pharm Stefanie Lehenauer

Stefanie Lehenauer ist seit 2020 freie Autorin bei Medikamio und studierte Pharmazie an der Universität Wien. Sie arbeitet als Apothekerin in Wien und ihre Leidenschaft sind pflanzliche Arzneimittel und deren Wirkung.

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