Efficacy and safety of willow bark extract in the treatment of osteoarthritis and rheumatoid arthritis: results of 2 randomized double-blind controlled trials.
OBJECTIVE
To investigate the efficacy and safety of a standardized willow bark extract in patients with osteoarthritis (OA) and rheumatoid arthritis (RA).


METHODS
We studied 127 outpatients with hip or knee OA and a WOMAC pain score of at least 30 mm and 26 outpatients with active RA in 2 randomized, controlled, double-blind trials with followup for 6 weeks. OA trial: Patients were randomized to receive willow bark extract, corresponding to 240 mg of salicin/day, diclofenac 100 mg/day, or placebo (n = 43, 43, and 41, respectively). Main outcome measure was the pain subscore of the WOMAC OA Index. RA trial: Patients were randomized to receive willow bark extract, corresponding to 240 mg salicin/day (n = 13) or placebo (n = 13). Main outcome measure was the patient's assessment of pain rated on a 100 mm visual analog scale (VAS).


RESULTS
OA trial: WOMAC pain scores decreased by 8 mm (17%) in the willow bark group and by 23 mm (47%) in the diclofenac group, compared with 5 mm (10%) in the placebo group. The difference between willow bark extract and placebo was not statistically significant (-2.8 mm; 95% CI -12.1 to 6.4 mm; p = 0.55, ANCOVA), but the difference between diclofenac and placebo was highly significant (-18.0 mm; 95% CI -27.2 to -8.8 mm; p = 0.0002, ANCOVA). RA trial: The mean reduction of pain on the VAS was -8 mm (15%) in the willow bark group compared with -2 mm (4%) in the placebo group. The difference was not statistically significant (estimated difference -0.8 mm; 95% CI -20.9 to 19.3 mm; p = 0.93, ANCOVA).


CONCLUSIONS
The OA study suggested that the willow bark extract showed no relevant efficacy in patients with OA. Similarly, the RA trial did not indicate efficacy of this extract in patients with RA.
Biegert
Claudia
C
Pharmaceutical Institute, Eberhard Karls-Universität, Tübingen, Germany.
Wagner
Irmela
I
Lüdtke
Rainer
R
Kötter
Ina
I
Lohmüller
Claudia
C
Günaydin
Ilhan
I
Taxis
Katja
K
Heide
Lutz
L
D000284:Administration, Oral; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D018501:Antirheumatic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000503:physiopathology; D004008:Diclofenac / Q000627:therapeutic use; D004311:Double-Blind Method; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000188:drug therapy* / Q000503:physiopathology; D024301:Plant Bark / Q000737:chemistry*; D010936:Plant Extracts / Q000008:administration & dosage / Q000627:therapeutic use*; D032108:Salix / Q000737:chemistry; D012720:Severity of Illness Index; D016896:Treatment Outcome
D000894:Anti-Inflammatory Agents, Non-Steroidal; D018501:Antirheumatic Agents; D010936:Plant Extracts; D004008:Diclofenac