Diclofenac topical solution compared with oral diclofenac: a pooled safety analysis

Sanford H Roth¹, Philip Fuller^2
1Arizona Research and Education, Arthritis Laboratory, Arizona State University, Phoenix, AZ, USA; ²Medical Affairs, Covidien, Hazelwood, MO, USA

Background: Topical nonsteroidal anti-inflammatory drug (NSAID) formulations, which produce less systemic exposure compared with oral formulations, are an option for the management of osteoarthritis (OA). However, the overall safety and efficacy of these agents compared with oral or systemic therapy remains controversial.
Methods: Two 12-week, double-blind, double-dummy, randomized, controlled, multicenter studies compared the safety and efficacy profiles of diclofenac topical solution (TDiclo) with oral diclofenac (ODiclo). Each study independently showed that TDiclo had similar efficacy to ODiclo. To compare the safety profiles of TDiclo and ODiclo, a pooled safety analysis was performed for 927 total patients who had radiologically confirmed symptomatic OA of the knee. This pooled analysis included patients treated with TDiclo, containing 45.5% dimethyl sulfoxide (DMSO), and those treated with ODiclo. Safety assessments included monitoring of adverse events (AEs), recording of vital signs, dermatologic evaluation of the study knee, and clinical laboratory evaluation.
Results: AEs occurred in 312 (67.1%) patients using TDiclo versus 298 (64.5%) of those taking ODiclo. The most common AE with TDiclo was dry skin at the application site (24.1% vs 1.9% with ODiclo; P < 0.0001). Fewer gastrointestinal (25.4% vs 39.0%; P < 0.0001) and cardiovascular (1.5% vs 3.5%; P = 0.055) AEs occurred with TDiclo compared with ODiclo. ODiclo was associated with significantly greater increases in liver enzymes and creatinine, and greater decreases in creatinine clearance and hemoglobin (P < 0.001 for all).
Conclusions: These findings suggest that TDiclo represents a useful alternative to oral NSAID therapy in the management of OA, with a more favorable safety profile.

Keywords: diclofenac, gastropathy, oral NSAIDs, osteoarthritis, topical NSAIDs