Willow bark extract STW 33-I in the long term treatment of osteoarthritic and back pain

The efficacy and safety of willow bark extract in the therapy of painful disorders of the musculosceletal system has been shown in a large number of clinical studies, but only for shorter treatment periods. The aim of this long term postmarketing surveillance study with STW 33-I (Proaktiv®, extraction solvent water; drug extract ratio 16–23:1) was the documentation of the treatment of patients suffering mainly from osteoarthritic and back pain for a period of up to 6 month. An extensive case report form with pain questionnaires and patient diary was used to evaluate the outcome of the treatment. 350 patients were included. 62% of them were treated with STW 33-I as a mono therapy, 28% with a combination of STW 33-I and NSAIDs, and 5% with opioids in addition. A first evaluation of the pain intensity (measured by Visual Analogue Scale VAS 0–100) over the treatment period shows mean improvements of resp. 23.5 for STW 33-I only, 18.8 for STW 33-I and NSAIDs, 21.2 for STW 33-I, NSAIDs and opioids simultaneously.

Pain intensity was also evaluated with other scales for pain intensity at rest and in motion and for pain duration, and with respect to further subgroups and correlations. Adverse events were registered as well. Within the limitations of a pragmatic design of postmarketing surveillance, these data give a hint to an effectiveness of willow bark extract over 6 months, as a monotherapy and even in combination with conventional analgetics.