Osteoarthritis therapy--are there still unmet needs?

Non-steroidal anti-inflammatory drugs (NSAIDs) and selective cyclooxygenase (COX)-2 inhibitors are commonly used to control pain and inflammation in osteoarthritis. However, these agents have been associated with gastrointestinal, renal and cardiovascular adverse effects. Together, these complications indicate a clear unmet need in the safety of current treatment options for the management of osteoarthritis. NSAIDs are known to have adverse gastrointestinal effects, and more recently it has been suggested that some selective COX-2 inhibitors are also associated with serious gastrointestinal complications. Selective COX-2 inhibitors have a similar capacity to NSAIDs to delay ulcer healing, and may not significantly decrease the incidences of perforation, ulceration and bleeding (the most clinically relevant gastrointestinal endpoints) compared with NSAIDs. These effects may be due to overlapping roles of COX-1 and COX-2 in physiological and pathophysiological processes. Furthermore, as COX-2 is integrally involved in renal homeostasis, selective COX-2 inhibitors are associated with negative effects on kidney function similar to those seen with NSAIDs. Electrolyte disturbances, oedema and hypertension have been correlated with the use of both drug classes. Additionally, selective COX-2 inhibitors have the potential to increase cardiovascular events, although further research is required to clearly determine such a risk. With the current unmet needs in the treatment of osteoarthritis, the opportunity exists for the development of new therapies. Novel agents include the COX-inhibiting nitric oxide donors and the lipoxygenase (LOX)/COX inhibitor licofelone. Initial results suggest that these therapies may have tolerability advantages over the NSAIDs and selective COX-2 inhibitors.