Chlorpromazine dose for people with schizophrenia
There are 24 million people in the world with schizophrenia according to the World Health Organisation (WHO), of which 90 per cent live in the developing world and are not using pharmaceutical treatments.
Schizophrenia is a long-term mental illness that causes people to
have false perceptions of the senses (hallucinations), see the world in
a different way from the majority (delusions), or to withdraw socially
and psychologically ('negative' symptoms).
This illness can
separate people from their peers in a profound way. Antipsychotic
medication can reduce these symptoms in most people and improve their
functioning. Chlorpromazine is the oldest of these medications and the
most readily available, especially in the developing world. This review
looks at trials that try to find the optimum dose of chlorpromazine for
people with schizophrenia.
Four trials were identified, which
included a total of 1012 people. All of them were carried out before
1980, the participants were all in hospital, and no trial was longer
than 26 weeks - indeed two were only 12 weeks. Three trials compared
low doses of chlorpromazine to medium doses (174 people) and one trial
compared low doses to very high doses (838 people). When comparing a
low dose to a medium dose, the low dose was significantly better in
stopping people from withdrawing socially (withdrawal/retardation). It
also was less likely to cause people to adopt strange postures
(dystonia) and to allow people to have a better general state of life
in the medium term (up to 26 weeks). However these trials contained a
relatively small number of people. When low doses were compared to what
today would be a very high dose, those in the high dose group had
significantly more adverse effects but showed a small but significant
improvement in general functioning.
Chlorpromazine has been
available since the 1950s and is one of the three antipsychotic drugs
on the WHO essential drug list. It is still extensively used to treat
many people with schizophrenia, especially in the developing world.
Therefore it is surprising to find that so few studies have been done
to determine the optimal dose. Over time the maximum recommended dose
has been reduced considerably, presumably in response to observation
from clinicians and the personal experience of those taking it.
Therefore,
a good randomised controlled trial of low and medium doses of
chlorpromazine for people in the community (concentrating on adverse
effects and long-term acceptability) would benefit those with
schizophrenia who take this medication.
