The relationship between the reporting of euphoria events and early treatment responses to pregabalin: an exploratory post-hoc analysis
Received 21 December 2018
Accepted for publication 2 July 2019
Published 22 August 2019 Volume 2019:12 Pages 2577—2587
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 4
Editor who approved publication: Dr Michael A Überall
Bruce Parsons,1 Rainer Freynhagen,2,3 Stephan Schug,4,5 Ed Whalen,1 Marie Ortiz,1 Pritha Bhadra Brown,1 Lloyd Knapp6
1Pfizer Inc, New York, NY, USA; 2Department of Anesthesiology, Critical Care Medicine, Pain Therapy & Palliative Care, Pain Center Lake Starnberg, Benedictus Hospital, Tutzing, Germany; 3Department of Anesthesiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany; 4Discipline of Anaesthesiology and Pain Medicine, Medical School, University of Western Australia, Perth, WA, Australia; 5Department of Anaesthesia and Pain Medicine, Royal Perth Hospital, Perth, WA, Australia; 6Pfizer Inc, Groton, CT, USA
Correspondence: Bruce Parsons
Pfizer Inc, 235 East 42nd Street, New York, NY, USA
Tel +1 212 573 1649
Background: Euphoria is a complex, multifactorial problem that is reported as an adverse event in clinical trials of analgesics including pregabalin. The relationship between the reporting of euphoria events and pregabalin early treatment responses was examined in this exploratory post-hoc analysis.
Methods: Data were from patients with neuropathic or non-neuropathic chronic pain enrolled in 40 randomized clinical trials, who received pregabalin (75–600 mg/day) or placebo. Reports of treatment-emergent euphoria events were based on the Medical Dictionary of Regulatory Activities preferred term “euphoric mood”. Prevalence rates of euphoria events overall and by indication were assessed. Post-treatment endpoints included ≥30% improvements in pain and sleep scores up to 3 weeks as well as a ≥1-point improvement in daily pain score up to 11 days after treatment.
Results: 13,252 patients were analyzed; 8,501 (64.1%) and 4,751 (35.9%) received pregabalin and placebo, respectively. Overall, 1.7% (n=222) of patients reported euphoria events. Among pregabalin-treated patients, a larger proportion who reported euphoria events achieved an early pain response compared with those who did not report euphoria (30% pain responders in week 1 with euphoria events [43.0%], without euphoria events [24.2%]). Results were similar for weeks 2 and 3. For Days 2–11, a larger proportion of pregabalin-treated patients with (relative to without) euphoria events were 1-point pain responders. Findings were similar in pregabalin-treated patients for sleep endpoints (30% sleep responders in week 1 with euphoria events [50.7%], without euphoria events [36.1%]). Similar results were found for weeks 2 and 3. Patients who received placebo showed similar patterns, although the overall number of them who reported euphoria events was small (n=13).
Conclusion: In patients who received pregabalin for neuropathic or non-neuropathic chronic pain, those who experienced euphoria events may have better early treatment responses than those who did not report euphoria events.
Keywords: euphoria, pain, pregabalin, sleep
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