By Louise Gagnon
MONTREAL -- September 18, 2009 -- The administration of a viscosupplement via injection to treat osteoarthritis (OA) of the knee demonstrates the ability to provide prolonged pain relief, according to an analysis presented here September 12 at the 2009 World Congress of the Osteoarthritis Research Society International (OARSI).
The 13-week extension phase included 258 patients of the 350 patients who participated in the initial 13-week trial. A total of 199 patients were re-administered a single intra-articular injection of hyaluronate (Gel-200) while 74 were followed to evaluate ongoing efficacy of the compound.
Patients who entered the extension study discontinued current OA therapies, and they had Western Ontario and McMaster Universities (WOMAC) pain subscores of 40 mm or more in the affected knee and up to 20 mm in the contralateral knee.
Herbert S. Baraf, MD, Arthritis and Rheumatism Associates, Wheaton, Maryland, and George Washington University, Washington, DC, noted that the hyaluronate injection has a cross-linked formulation.
"The presumption is that it would be longer acting because it has a higher molecular weight and stays in the joint longer and exerts more influence," said Dr. Baraf in an interview, adding that a viscosupplement is generally thought to provide more sustained pain control than a steroid injection does.
Patients with osteoarthritis have become reluctant to use nonsteroidal, anti-inflammatory drugs as therapy for very long term, so they are seeking alternative treatment options, such as hyaluronates, according to Dr. Baraf. "They [viscosupplements] fill a niche, particularly in treating [OA of] the knee," Dr. Baraf told DocGuide.
Investigators found that injection of hyaluronate demonstrated statistically significant advantages in durability of response, using treatment, age, and WOMAC pain subscores at study entry as covariates for the 2 study endpoints.
All participants who received open-label, intra-articular hyaluronate showed improvement from open-label baseline in WOMAC measures including pain, stiffness, function, and total measure, as well as global assessments by the subject and physician (P < .0001).
There was no significant difference between the incidence of side effects within 24 hours of injection in the extension phase and the initial phase of the study.
Funding for this study was provided by Seikagaku Corporation.
[Presentation title: Duration of a Single Intra-articular Injection of Gel-200 and Safety of Re-treatment of Gel-200, A New Cross-Linked Formulation of Hyaluronic Acid (HA) in the Treatment of Symptomatic Osteoarthritis (OA) of the Knee. Abstract 341]
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