Researchers from The University of Queensland and the Queensland Centre for Mental Health Research have shown that people using the antipsychotic clozapine do not need regular blood monitoring after two years.
Dr Korinne Northwood, from UQ’s Faculty of Medicine, explained that the findings could improve access to the drug and outcomes for patients.
“Clozapine is generally prescribed for treatment-resistant schizophrenia, but it can interfere with the production of neutrophils, a kind of white blood cell, leaving people dangerously vulnerable to infection in the first month or so after starting the drug,” Dr Northwood said.
“At the moment, people taking clozapine have weekly blood tests for the first 18 weeks, then monthly tests for as long as they are on the medication.
“If their neutrophil levels drop dramatically, they have to stop taking clozapine.
“In this study, we conducted a huge analysis of historical data from 26,630 people taking clozapine across Australia and New Zealand.
“Of this group, 313 had to stop taking clozapine because of seriously low neutrophil levels, with the overwhelming majority of those incidences falling within the first 18 weeks of taking the drug.
“But, we found that once people had taken clozapine for 2 years, the rate of someone experiencing seriously low neutrophils was just 0.001 per cent per week.”
Clozapine is used to treat schizophrenia when other antipsychotic medicines either have not worked or have caused severe side effects.
Professor Dan Siskind from UQ’s Faculty of Medicine explained that the drug effectively reduced hospitalisations and mortality for the third of people with schizophrenia who are treatment resistant.
“Clozapine is a necessary, lifesaving medication for many people, but the weekly and then monthly blood testing which is currently mandated presents a burden to consumers.
“What we’ve found in this study is that after being monitored on clozapine for two years, the risk of experiencing dangerously low neutrophils is so low that people don’t need to be doing blood tests every single month for the rest of their lives – especially if they have tried clozapine before.
“Clozapine is under-prescribed globally, and it’s possible this is part due to fear among clinicians of the risks and the burden of lifelong monitoring on patients.
“We hope this study will provide the basis for a change in practice, making clozapine more accessible to those who need it and improving the lives of people on the drug.”
The research is published in The Lancet Psychiatry.
Media: UQ Faculty of Medicine, med.media@uq.edu.au , +61 436 368 746.
