Thorazine (Chlorpromazine) Drug Class
Thorazine (chlorpromazine) is a first-generation (typical) antipsychotic medication belonging to the phenothiazine class of drugs. 1, 2
Classification Details
- Chlorpromazine is specifically classified as an aliphatic phenothiazine, which was one of the first antipsychotic medications developed 3
- It is considered a "low-potency" typical antipsychotic, meaning it is more sedating but produces fewer extrapyramidal symptoms compared to "high-potency" agents like haloperidol 1
- Chlorpromazine exerts its primary effect as a central nervous system (CNS) dopamine receptor antagonist 1
- It also has significant activity at other receptor types, including anticholinergic, antihistaminic, and alpha-adrenergic receptors, which contributes to its side effect profile 4
Pharmacological Properties
- The chemical formula of chlorpromazine hydrochloride is 2-chloro-10-[3-(dimethylamino) propyl] phenothiazine monohydrochloride (C17H19ClN2S.HCl) 5
- It has a molecular weight of 355.33 g/mol 5
- Chlorpromazine occurs as a white or slightly creamy white crystalline powder that darkens on prolonged exposure to light 5
Clinical Applications
- Chlorpromazine is used for the management of acute episodes and prevention of relapse in schizophrenia 2
- It is effective for treating severe agitation and violent behavior, particularly in emergency settings 2
- Non-psychiatric indications include treatment of intractable nausea and vomiting, and as an adjunctive treatment for persistent hiccups 2
- It can be used for sedation in the management of refractory symptoms at end of life 2
- In pediatric populations, chlorpromazine may be used for severe behavioral problems, though careful monitoring is required due to its side effect profile 2
Comparison to Other Antipsychotics
- Chlorpromazine has been used as a "gold standard" to compare the efficacy of older and newer antipsychotic drugs 3
- When compared to atypical antipsychotics, chlorpromazine causes significantly more extrapyramidal symptoms 3
- Quality of life ratings tend to be more favorable with atypical antipsychotics like olanzapine, risperidone, and quetiapine compared to chlorpromazine 3
Important Clinical Considerations
- Chlorpromazine can cause QTc prolongation, potentially resulting in torsades de pointes, requiring ECG monitoring 2
- It is more likely to cause hypotension than some other antipsychotics 2
- Co-administration with other QT-prolonging medications should be avoided due to increased risk of cardiac arrhythmias 2
- Regular assessment of cardiovascular status, extrapyramidal symptoms, and metabolic parameters is essential during treatment 2
Chlorpromazine remains on the World Health Organization's Model Lists of Essential Medicines as one of its five medicines used in psychotic disorders, despite the development of newer antipsychotic medications 6.