Experts have warned that antipsychotic drugs could increase the risk of dangerous blood clots.
Researchers found an increased risk of potentially fatal blood clots in people taking the drugs, with a higher risk for those on newer types of medication.
Published online in the BMJ, it looked at people taking older “typical” antipsychotics (also called conventional antipsychotics), alongside newer “atypical” drugs. The most recent atypical antipsychotics were developed in the 1990s.
The research involved data from more than 25,000 people who suffered blood clots, taken from 525 GP practices in the UK.
In the study, almost 16,000 of these suffered a deep vein thrombosis and just over 9,000 suffered a clot on the lung, called a pulmonary embolism. A further 90,000 people without a clot acted as a control group.
The results showed that people who had taken antipsychotic drugs in the previous two years had a 32% greater risk of any type of blood clot, while new patients who had started a drug in the previous three months had about twice the risk.
Risks were found to be almost three times higher for people prescribed atypical compared with conventional drugs. However, the overall risk of a clot remained small, with four extra cases estimated per 10,000 patients treated over the course of one year. For people aged 65 and over, the number of extra cases was estimated at 10.
According to the Medicines and Healthcare products Regulatory Agency (MHRA), the following atypical antipsychotics are licensed for use in the UK: amisulpride (brand name Solian), aripiprazole (Abilify), clozapine (Clozaril, Denzapine), olanzapine (Zyprexa), paliperidone (Invega), risperidone (Risperdal, Risperdal Consta) and zotepine (Zoleptil).