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Radafaxine is the single-isomer version of a molecule most people have already taken without knowing it, the active (2S,3S)-hydroxybupropion metabolite that does a good chunk of the work in ordinary bupropion. GlaxoSmithKline isolated and purified this metabolite hoping a cleaner single-enantiomer dopamine reuptake inhibitor could outperform bupropion itself, and pushed it into trials across depression, bipolar disorder, obesity, fibromyalgia, and neuropathic pain. None of that data was ever published; GSK simply stopped the program, reportedly over underwhelming test results that could not justify differentiating it from a cheap generic parent drug. It stands as a reminder that isolating a drug's active metabolite does not automatically make a better medicine.
- none independently confirmed; trial data across all indications remains unpublished
- Radafaxine was tested for five different conditions, depression, bipolar disorder, obesity, fibromyalgia, and neuropathic pain, and failed to reach the market in any of them.
Mechanism
Selective () inhibitor; the purified (2S,3S) of hydroxybupropion, the major active responsible for much of bupropion's clinical activity.
Safetyrisks and cautions, not medical advice
More than 1,200 patients were enrolled across three completed GlaxoSmithKline depression trials in 2003 and 2004, and not one of those studies has posted a result or an adverse-event table. That silence is the safety story. What can be reasoned rather than read is that this molecule is the active metabolite of bupropion, so the parent drug's profile is the sensible expectation: insomnia, dry mouth, appetite loss, raised blood pressure and heart rate, and the dose-related seizure risk that keeps bupropion away from anyone with a seizure disorder or an eating disorder. None of that has been confirmed for the isolated enantiomer.
History
Developed by GlaxoSmithKline in the early-to-mid 2000s; tested in Phase II across depression, bipolar depression, obesity, fibromyalgia, and neuropathic pain, then quietly discontinued with no clinical trial results ever published.
Subjective profileweighing the evidence above
An unpublished dead end that never showed it could beat its own parent drug, bupropion, on any measure that mattered.
Resources
This entry is here for reference.
Reviews
My notesprivate to this device
FAQ
Is radafaxine basically bupropion?
It is the purified active metabolite of bupropion, hydroxybupropion, isolated as a single enantiomer; the hope was a cleaner, more potent version, but it never proved itself better.
Why was radafaxine dropped?
GSK ended development citing poor test results; the studies across depression, obesity, fibromyalgia, and neuropathic pain were never published, so the exact reasons remain opaque.
Notes and cautions
- unknown in detail; GSK cited poor test results as the reason for discontinuation without releasing specifics