New NSAID patch matches diclofenac gel for pain management in knee osteoarthritis

The novel topical nonsteroidal anti-inflammatory drug (NSAID) S-flurbiprofen plaster provides relief from pain that appears similar to that achieved with diclofenac gel in patients with knee osteoarthritis (OA), in addition to being well tolerated, according to data from an open-label, noninferiority phase III study.

In a cohort of 289 knee OA patients (average age 55 years, 87.2 percent female), the least squares mean changes from baseline to week 2 in knee pain experienced when rising from a chair (assessed using a visual analogue) were 41.22 mm with S-flurbiprofen 40 mg plaster (n=143) and 36.01 mm with diclofenac 2 g gel (n=146). A difference of 5.51 indicated that the patch was noninferior. [Int J Rheum Dis 2022;doi:10.1111/1756-185X.14307]

There were more patients treated with S-flurbiprofen plaster vs diclofenac gel who achieved a ≥50-percent reduction in pain intensity (83.8 percent vs 66.7 percent; p=0.001). Between-group differences were also noted in clinical symptoms (p=0.024), pain on walking (p=0.020), and the global assessment by both investigator and patient (p<0.001).

Meanwhile, the use of rescue drugs during the treatment period was similar in the two treatment groups (38.8 percent vs 36.6 percent; mean total number of days, 1.09 vs 0.97). The same was true for the incidence of adverse events (5.8 percent vs 5.2 percent). Most of the AEs in both groups were mild, and none led to treatment discontinuation.

The present data, according to the study authors, show that S-flurbiprofen plaster has a strong effect on pain, which is considered to be a boon in the management of OA since pain greatly impairs the quality of life of patients. [BMC Musculoskelet Disord 2012;13:168]

Previous trials have shown the novel topical NSAID to have a remarkable analgesic effect compared with placebo and flurbiprofen patch, as well as to be noninferior to conventional treatment with the combination of oral (such as celecoxib) plus topical (such as ketoprofen) NSAIDs. [J Pain Res 2017;10:867-880; Mod Rheumatol 2017;27:130-136; Prog Rehabil Med 2021;6:20210029]

The S-flurbiprofen plaster contains the active form of the widely used racemic flurbiprofen (FP) and exerts anti-inflammatory and analgesic effect. It is a tape-type patch and formulated to allow sufficient deep-tissue penetration of the drug. [Drug Dev Res 2016;77:20-28; Pharmacol Pharm 2016;7:305-312; Eur J Clin Pharmacol 2016;72:53-59]

In the study, the differences in efficacy between S-flurbiprofen plaster and diclofenac gel might have a lot to do with their percutaneous absorption rate, the authors explained. The former has a high percutaneous absorption rate (50–70 percent) and can penetrate the deep tissue of the knee joint (synovial tissue and fluid). [Eur J Clin Pharmacol 2016;72:53-59]

“Diclofenac gel can also penetrate subdermal tissues, including the synovial tissue. However, the reports of the concentration of diclofenac within deep tissues after topical administration are variable and not consistent… The absorption rate of diclofenac gel used in this study was reported as 6 percent, which is much lower than that of S-flurbiprofen plaster,” they said. [Rheumatol Ther 2020;7:217-236]

Despite the presence of study limitations, including the open-label design and foregoing the use of the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) knee pain score as the primary outcome, “the efficacy results were obtained by once-daily application of S-flurbiprofen plaster, although topical NSAID gels including diclofenac gel need to be applied multiple times per day,” the authors said.

They were positive that the new topical NSAID patch will help improve both medication adherence and the quality of life of OA patients.