Penetration of topical diclofenac into synovial tissue and fluid of osteoarthritic knees: a multicenter, randomized, placebo-controlled, pharmacokinetic study.

Topical diclofenac diethylamine 2.32% w/w gel penetrated into the osteoarthritic knee after repeated application and remained detectable in synovial tissue and fluid at the end of the final 12 h dosing cycle.