In a significant clinical trial, the drug pramipexole has been shown to be more effective than a placebo in reducing symptoms of treatment-resistant depression (TRD) when used alongside ongoing antidepressant medication. The trial, supported by the National Institute for Health and Care Research (NIHR) and published in The Lancet Psychiatry, involved 150 patients with TRD. Participants were divided equally between those receiving pramipexole and those given a placebo over 48 weeks.
Patients taking pramipexole reported a notable reduction in symptoms by the twelfth week of treatment, with benefits continuing throughout the year-long study. However, side effects such as nausea, sleep disturbances, and dizziness led approximately one-fifth of participants on pramipexole to leave the trial early.
Professor Michael Browning from the Department of Psychiatry at the University of Oxford led the research. He stated: "Effectively treating people who have not responded to first-line interventions for depression is a pressing clinical problem and there has long been an urgent need to find new treatments." He added that these findings represent "a significant breakthrough" for patients unresponsive to other treatments.
Pramipexole is primarily used for Parkinson’s disease due to its ability to boost dopamine levels in the brain, differing from most antidepressants that target serotonin. Professor Browning emphasized the need for further research into minimizing side effects, assessing cost-effectiveness, and comparing pramipexole with other adjunctive treatments.
The study also highlighted previous promising research on pramipexole's use in depression but noted limited data on long-term outcomes until now. Current guidelines suggest adding treatments like lithium or antipsychotics for TRD; however, these are not universally effective.
Phil Harvey from Oxfordshire shared his experience with pramipexole during the trial: "Within a few weeks I felt the effects, it was amazing... It was dragging me out of this dark black hole that I’ve been in for years."
Participants were recruited nationwide through NIHR-funded mood disorder clinics associated with Oxford's MH-TRC Mission. These clinics assess patients with challenging mood disorders and offer them participation in research studies while supporting primary care services with assessment and treatment advice.
The paper titled ‘Pramipexole augmentation for the acute phase of treatment-resistant, unipolar depression: a placebo-controlled, double-blind, randomised trial in the UK’ is available in The Lancet Psychiatry.