Focus on Alternative and Complementary Therapies
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Focus Alternat Complement Ther©2005 Pharmaceutical Press
Focus Altern Complement Ther 2002; 7: 100
Willow bark, often cited as the natural precursor of the salicylates, has a sound tradition in inflammatory disorders such as rheumatoid diseases. Several clinical studies show efficacy of standardised willow bark preparations (e.g. Assalix) in chronic low back pain and osteoarthritis. We examined the anti-inflammatory, analgesic and antipyretic activities of a standardised willow bark extract (ES; 11–13% salicin) compared with acetylsalicylic acid (ASA).
Standard in vivo assays for anti-inflammatory, analgesic and antipyretic activities were used. Mice or rats were treated with 60 mg/kg, 100 mg/kg, or 120 mg/kg of ES or 100 mg/kg, 300 mg/kg, or 600 mg/kg ASA. An open field test was also conducted to study possible effects on the central nervous system. Results were compared with literature.
All doses of ES showed analgesic and anti-inflammatory activities. Only the highest dose of ASA had a similar potency for both activities. Regarding antipyretic activities, ASA appeared to have a more pronounced and faster activity. No disturbing effect with respect to the central nervous system could be found for the SE treatment. In the literature, the ED50 values were 3.4 ml/kg for adjuvant-induced arthritis, 1.4 ml/kg for heat-induced inflammation, 3.7 ml/kg for dextran-induced hind paw oedema, and 0.5 ml/kg for carrageenan-induced hind paw oedema. An antipyretic activity has also been shown for doses below 1.0 ml/kg.
Strong activities in important inflammatory models have been found for ES of defined chemical quality. It is remarkable and unexpected that the doses of SE needed for a similar size of effect were much lower than those of ASA.
