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Active ingredient: Propiomazine - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

  • Sedatives and Hypnotics

Dosage Forms

  • Injection (20 mg/mL)

Brands / Synonyms

Largon; Phenoctyl; Propiomazina [Inn-Spanish]; Propiomazine [Usan:Ban:Inn]; Propiomazinum [Inn-Latin]; Propionylpromethazine


Used to produce sleepiness or drowsiness and to relieve anxiety before or during surgery or certain procedures. Also used with analgesics during labor to produce drowsiness and relieve anxiety.


Propiomazine, an atypical antipsychotic agent, is used to treat both negative and positive symptoms of schizophrenia, acute mania with bipolar disorder, agitation, and psychotic symptoms in dementia. Future uses may include the treatment of obsessive-compulsive disorder and severe behavioral disorders in autism. Structurally and pharmacologically similar to clozapine, propiomazine binds to alpha(1), dopamine, histamine H1, muscarinic, and serotonin type 2 (5-HT2) receptors.

Mechanism of Action

Propiomazine is an antagonist at types 1, 2, and 4 dopamine receptors, serotonin (5-HT) receptor types 2A and 2C, muscarinic receptors 1 through 5, alpha(1)-receptors, and histamine H1-receptors. Propiomazine's antipsychotic effect is due to antagonism at dopamine and serotonin type 2 receptors, with greater activity at serotonin 5-HT2 receptors than at dopamine type-2 receptors. This may explain the lack of extrapyramidal effects. Propiomazine does not appear to block dopamine within the tubero-infundibular tract, explaining the lower incidence of hyperprolactinemia than with typical antipsychotic agents or risperidone.


Not Available


Rare, serious side effects include convulsions (seizures); difficult or unusually fast breathing; fast or irregular heartbeat or pulse; fever (high); high or low blood pressure; loss of bladder control; muscle stiffness (severe); unusual increase in sweating; unusually pale skin; and unusual tiredness or weakness.

Biotrnasformation / Drug Metabolism

Unknown, but most likely hepatic as with other phenothiazines.


Contraindicated in thrombophlebitis and neuroleptic malignant syndrome (NMS).

Drug Interactions

May interact with phenylalanine (may worssen the side effect of tardive dyskinesia associated with antipsychotic medications), alcohol or central nervous system (CNS) depression–producing medications (concurrent use may increase the CNS depressant effects of either these medications or propiomazine), epinephrine (concurrent use with propiomazine may block the alpha-adrenergic effects of epinephrine, allowing beta-adrenergic effects to predominate, thus possibly resulting in severe hypotension), hypotension-producing medications (concurrent use may potentiate the hypotensive effect of propiomazine), mecamylamine or trimethaphan (concurrent use with propiomazine may potentiate the hypotensive response, with increased risk of severe hypotension, shock, and cardiovascular collapse during surgery), and ketamine (concurrent use of ketamine, especially in high doses or when rapidly administered, with propiomazine may increase the risk of hypotension and/or respiratory depression).

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