A new 5-lipoxygenase inhibitor seems to be safe and effective for the treatment of osteoarthritis.

There is a clear need for both disease-modifying agents and alternative analgesic therapies in osteoarthritis. Currently, there are none of the former, and the latter are limited by adverse effects, particularly gastrointestinal and cardiovascular effects. A new class of analgesic agent that is under investigation inhibits 5-lipoxygenase (5-LOX), the enzyme that catalyzes the conversion of membrane-bound arachidonic acid to leukotrienes. As leukotrienes are implicated in a wide variety of pathologies, the potential of 5-LOX inhibitors has been explored in conditions as diverse as asthma, acute mountain sickness and coronary artery disease. A new 5-LOX inhibitor, derived from a herb, has undergone a phase II trial in osteoarthritis with promising results. Although a putative mechanism of action suggests a disease-modifying effect, the important outcomes from this trial are good symptom response and a low adverse effect profile, albeit in the small number of patients studied.