Diclofenac Sodium 1% Gel Safe for Long-Term Treatment of Osteoarthritis in Elderly

HONOLULU, HI—Diclofenac sodium 1% gel is well tolerated for up to 1 year for the relief of osteoarthritis (OA) pain in patients both <65 years and ≥65 years of age, according to 12-month data presented at the American Pain Society's 31st Annual Scientific Meeting.

The study investigators sought to perform an age analysis of the long-term safety of diclofenac sodium 1% gel in an open-label extension of two double-blind, randomized, 3-month safety trials of topical diclofenac sodium 1% gel in patients ≥35 years with a ≥6-month history of symptomatic Kellgren-Lawrence grade 1–3 knee OA.  Adverse events were monitored throughout the study and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, stiffness, and physical function subscales were assessed at baseline and 3, 6, 9, and 12 months.

The safety population (n=947) received ≥1 dose of diclofenac sodium gel or placebo during the 12-week study or the extension phase. Of these patients 575 were <65 years and 372 were ≥65 years of age. Patients were instructed to apply 4g of diclofenac sodium gel to one or both knees 4 times daily. Duration of therapy was 9 months for continuing patients and 12 months for new patients. Rescue medication in the form of acetaminophen (≤4g/day) was allowed.

A comparable number of patients in both age groups experienced ≥1 adverse event, 68.2% and 67.2%, respectively, for patients <65 years and ≥65 years. Application-site dermatitis occurred less frequently in patients <65 years (8.7%) compared with patients ≥65 years (13.2%). However, patients <65 years experienced more gastrointestinal events (9.4%) and cardiovascular events (3.5%) than patients ≥65 years (6.7% and 3.2%, respectively).

The efficacy population (n=291) included patients who completed WOMAC assessments through the 12-month visit. Subpopulations by age (<65 years [n=173] and ≥65 years [n=118]) had similar baseline Kellgren-Lawrence osteoarthritis severity grades and WOMAC pain, stiffness, and physical function subscale grades. Diclofenac sodium gel provided slightly greater pain relief in patients <65 years, but remained effective for both age groups.

Matthew Wieman, MD, from Endo Pharmaceuticals, John H. Peniston, DO, from Novartis Consumer Health, and colleagues concluded that topical diclofenac sodium gel was well tolerated in patients aged <65 and ≥65 years with OA pain for up to 1 year, supporting its use for relief of knee OA pain in younger and elderly adult patients.