Taking multiple antipsychotics increases risk of developing high blood pressure

Taking more than one antipsychotic at a time can increase a patient’s risk of developing high blood pressure, according to a study published in Schizophrenia Bulletin.

Researchers from the Applied Research Collaboration West (ARC West) and Bristol Medical School found that patients treated with multiple antipsychotics at the same time had a higher risk of developing high blood pressure than patients treated with only one antipsychotic. They did not, however, find evidence to suggest that taking more than one antipsychotic increased a patient’s risk of developing diabetes or abnormally high levels of fat in the blood (hyperlipidaemia).

Schizophrenia affects approximately one per cent of people worldwide. People with schizophrenia die on average 20 years before the healthy population and this gap may be widening. They often have a lower quality of life and are at increased risk of developing diabetes, obesity, high blood pressure and hyperlipidaemia.

The study team analysed data from the UK Clinical Practice Research Datalink (CPRD), a database which collects anonymised patient data from a network of GP practices across the UK. They reviewed the records of more than four thousand patients diagnosed with schizophrenia and registered at a GP practice between 1 July 1994 and 30 August 2018.

Their findings suggest that clinicians should consider a patient’s risk of developing high blood pressure when prescribing them more than one antipsychotic. Patients who take more than one antipsychotic at a time should have their blood pressure checked regularly. If needed, medication to reduce a patient’s blood pressure should be prescribed, which will also help reduce their risk of cardiovascular complications developing.

Researchers found evidence that the risk of developing high blood pressure was lower for those taking a combination of first- and second-generation antipsychotics, when compared to those taking only first-generation drugs. There was no evidence of a change in a patient’s risk for developing hyperlipidaemia or diabetes when comparing these drug combinations.

First-generation antipsychotics are known as typical antipsychotics. They work by blocking dopamine receptors to help a patient with their symptoms. Dopamine is a chemical released by the human body which plays a role in how we experience pleasure.

Second-generation antipsychotics are known as atypical antipsychotics. They work by partially blocking dopamine receptors and may affect other things, like serotonin. Serotonin is a chemical that carries messages between nerve cells in the brain and body. It plays a key role in regulating many bodily functions such as mood and sleep.

Dr Emily Eyles, lead author, said:

“While we know that second generation antipsychotics increase the risk of various adverse metabolic outcomes, our comparison between first- and second-generation antipsychotics suggested that the risk of high blood pressure is higher in people treated solely with first generation antipsychotics.

“This means that more research is needed, with larger sample sizes and a longer follow-up period per patient to confirm the associations we found in this study. Further, including patients in tertiary care, such as secure forensic mental health services, could enhance the results of future work.”