Review reveals lack of evidence for prescribing more than one anti-psychotic drug
4 September 2018
A review of studies into the effects of taking more than one anti-psychotic drug has revealed a lack of evidence on whether this can cause serious physical health problems.
People with schizophrenia die about 20 years earlier than those without a serious mental illness. This is partly because they are more likely to have serious health problems such as obesity, diabetes, high blood pressure and high cholesterol. All of these increase the risk of having a heart attack or stroke. People may be more likely to have these problems if they take more than one antipsychotic over a long time, but the review has shown that more research is needed to confirm this.
Many patients with schizophrenia are prescribed more than one anti-psychotic at a time, even though experts recommend that only one should be taken at a time. There is also no clear evidence that taking more than one is more effective.
The researchers found 12 systematic reviews, but the evidence found in these reviews was low quality, so the findings weren’t very reliable.
Most of the reviews included clozapine, a commonly prescribed antipsychotic which is used when a patient doesn’t respond to other antipsychotics.
There was some indication that drug combinations with aripiprazole can protect against diabetes and high blood fat levels, compared to combinations without aripiprazole or single drug therapy. But the data was from just a few small studies.
The only evidence on high blood pressure was from one low quality review which said taking more than one antipsychotic drug did not increase the risk of high blood pressure.
Most people with schizophrenia are treated by their GP and only severe cases are treated in hospitals or specialist centres. But none of the reviews separated results for patients treated at the GP from those treated in hospital.
With the existing evidence, we can’t be sure if taking more than one antipsychotic drug is effective or safe for most schizophrenia patients.
The team are working on the next phase of this project, which is to analyse routine data from GPs to understand the risk of getting diabetes, high blood pressure and high blood fat levels when taking more than one antipsychotic drug.