From the Guidelines
Haloperidol is generally considered more potent than chlorpromazine for treating acute psychosis and schizophrenia, but the choice between these medications should be individualized based on the patient's specific symptoms and side effect tolerance. For acute psychosis and schizophrenia, haloperidol is considered more potent on a milligram-per-milligram basis and may work faster for controlling acute agitation, as seen in a study by Baldessarini et al 1. Haloperidol typically requires lower doses (2-20mg daily) compared to chlorpromazine (200-800mg daily). However, chlorpromazine has a broader spectrum of activity and may be more effective for treating conditions with mixed symptoms. Both medications work by blocking dopamine D2 receptors in the brain, but chlorpromazine also affects multiple other neurotransmitter systems, giving it a different side effect profile.
- Key differences in side effects include:
- Haloperidol tends to cause more extrapyramidal symptoms (movement disorders)
- Chlorpromazine is more likely to cause sedation, orthostatic hypotension, and anticholinergic effects
- The most recent and highest quality study, a randomized trial by Thomas et al 1, compared the effectiveness of haloperidol and droperidol in treating agitation, but did not directly compare haloperidol and chlorpromazine. However, the study suggests that haloperidol may have a faster onset of action compared to other antipsychotics.
- It's also important to note that atypical antipsychotics, such as clozapine, have been shown to be effective in treating schizophrenia, especially in cases where traditional neuroleptics are not effective, as seen in a study by Kumra et al 1. However, the use of these agents in juveniles is still limited and requires further study.
- In terms of morbidity, mortality, and quality of life, the choice between haloperidol and chlorpromazine should be based on the individual patient's needs and medical history, as well as the potential side effects and benefits of each medication.
From the Research
Efficacy Comparison
- The study 2 found that haloperidol and chlorpromazine are equally effective when used at equivalent doses, but have different side-effect profiles.
- The efficacy outcome 'no significant improvement' tended to favour haloperidol, but this difference was not statistically significant (9 RCTs, n=400, RR 0.81 CI 0.64 to 1.04).
- Another study 3 compared haloperidol with other first-generation antipsychotics, including chlorpromazine, and found no clear evidence of a difference in terms of efficacy.
Side Effects
- Haloperidol was associated with significantly more movement disorders than chlorpromazine ('at least one extrapyramidal side effect': 6 RCTs, n=37, RR 2.2 CI 1.1 to 4.4, NNH 5 CI 3 to 33) 2.
- Chlorpromazine was associated with more frequent hypotension (5 RCTs, n=175, RR 0.31 CI 0.11 to 0.88, NNH 7 CI 4 to 25) 2.
- A systematic review 4 found that haloperidol was associated with significantly higher rates of extrapyramidal side effects, including parkinsonism and akathisia, compared to second-generation antipsychotics.
Dosage and Tolerability
- A study 5 found that a low dose of haloperidol (2 mg/d) was equally effective as a high dose (8 mg/d) in the treatment of first-episode psychosis, but was better tolerated with fewer extrapyramidal side effects.
- The review 6 noted that the criteria for choosing among antipsychotics are mainly pragmatic and include factors such as available formulations, metabolism, half-life, efficacy, and side effects in previous illness episodes.