Safety and tolerability of intra-articular hyaluronic acid (Sinovial®/GELSYN-3tm) injections in the treatment of knee osteoarthritis.

Osteoarthritis (OA) is a progressively degenerative joint disease, with a very high prevalence rate that is expected to increase worldwide with the ageing of the population. Considering that OA requires long-term treatment, therapies with minimal side effects and which can be repeated as needed are warranted. Hyaluronic acid (HA), a natural glycosaminoglycan with viscoelastic properties, is a major component of synovial fluid and the extracellular matrix of the joint cartilage, and plays key roles in maintaining synovial fluid viscosity and the bio-mechanical integrity of healthy cartilage. Intra-articular administration of exogenous HA has therefore been used to successfully improve the viscoelastic properties of the joint to improve lubrication, modulate inflammation and modify the catabolic micro-environment. Sinovial®/GELSYN-3TM is a sterile, non-pyrogenic formulation of highly purified, chemically unmodified HA of bio-fermentative origin, which has been introduced in several different concentrations in clinical use within the European market. This expert opinion reports on the published data regarding the efficacy and tolerability of first and multiple injection series of Sinovial®-based product formulations. The data regarding the tolerability of Sinovial® in patients with knee osteoarthritis were analyzed, showing that this formulation, beside favourable therapeutic effects, has a very good tolerability profile, with only mild, transient, and easily managed, local injection-site reactions and absence of systemic reactions. In particular, repetitive cycles of HA have been shown to yield positive results in terms of both efficacy and safety and therefore should be offered to patients who had undergone a successful first course of therapy when their symptoms reoccur.