#103 Duloxetine (Cymbalta®): Jack of All Trades, Master of None?

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- ≥50% improvement in pain: duloxetine 47% vs. placebo 29% (Number Needed to Treat (NNT) 6).
- Mean pain scores improved 2.66 with duloxetine and 1.62 on placebo (on 0–10 scale).
- Adverse events leading to discontinuation: duloxetine 60 mg/day 13.9% vs. placebo 8.3% (Number Needed to Harm (NNH) 18).
- Adverse events included nausea (NNH 9), somnolence (NNH 14), dry mouth (NNH 17), and dizziness (NNH 21).
- Increasing dose no advantage: no difference in response but more adverse events.
- RCT2 of 804 diabetic peripheral neuropathy patients treated with either duloxetine 60 mg/day or pregabalin 300 mg/day for eight weeks.
- ≥50% improvement in pain: duloxetine 40% vs. pregabalin 28% (NNT 9).
- ~12% discontinued treatment due to adverse effects in both groups.
- Trial sponsored by manufacturer of Cymbalta®.
- Previous small trials showed no conclusive difference between duloxetine and amitriptyline3,4 or pregabalin4,5 in neuropathic pain.
- Duloxetine is also efficacious in other chronic painful conditions, including fibromyalgia6 (NNT 8), chemotherapy-induced neuropathic pain (NNT ~9),7 and osteoarthritis of the knee (NNT 6–8).8,9
- For depression, duloxetine has similar efficacy and overall safety to other second generation antidepressants, with no clear advantages compared to other agents.10
- Duloxetine trials are at moderate-to-high risk of bias: industry funding, short duration, high risk of selective outcome reporting, high drop-out rates, multiple outcomes without adjustment and possible selective publication.