What is chlorpromazine?

First generation ‘typical’ antipsychotics such as chlorpromazine are an older class of antipsychotic than second generation ‘atypical’ antipsychotics. They are used primarily to treat positive symptoms including the experiences of perceptual abnormalities (hallucinations) and fixed, false, irrational beliefs (delusions). First generation antipsychotics may cause side effects which can differ depending on which antipsychotic is being administered and on individual differences in reaction to the drug. Reactions may include dyskinesias such as repetitive, involuntary, and purposeless body or facial movements, Parkinsonism (cogwheel muscle rigidity, pill-rolling tremor and reduced or slowed movements), akathisia (motor restlessness, especially in the legs, and resembling agitation) and dystonias such as muscle contractions causing unusual twisting of parts of the body, most often in the neck. These effects are caused by the dopamine receptor antagonist action of these drugs.

What is the evidence for chlorpromazine?

Moderate quality evidence finds chlorpromazine reduces rates of relapse and improves symptoms and functioning more than placebo, although chlorpromazine is more sedating, causes more lowering of blood pressure and more weight gain. For chlorpromazine dose, there was greater improvement in global state with high-dose (2gms/day) than low-dose (≤400mg/day) chlorpromazine, but less dystonia and extrapyramidal effects with low-dose chlorpromazine.

Compared to first-generation haloperidol, there was some benefit of chlorpromazine for sedation, but less benefit for any global improvement and study retention. Compared to first-generation piperacetine, there were no differences in global state, mental state or leaving the study early. Compared to first-generation metiapine, there were no differences in clinical improvement, and compared to first-generation penfluridol, there were no differences in leaving the study early. Movement disorders may be more frequent with haloperidol, while chlorpromazine was associated with more hypotension. The need for additional antiparkinsonian medication was less with chlorpromazine than with penfluridol.

Conpared to second-generation clotiapine, moderate to low quality evidence finds no differences in leaving the study early. Lower quality evidence is unable to determine any differences in symptoms or in rates of dyskinesia.

October 2020

Last updated at: 3:04 am, 14th October 2020
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