The effect of a topical curcumin formulation (VAS-101) on knee pain in adults with knee osteoarthritis: a randomised, double-blind, placebo-controlled study

Background The oral delivery of curcumin has been shown in several studies to have beneficial pain-relieving effects for the treatment of knee osteoarthritis. However, there has been limited investigation into its efficacy and tolerability when delivered topically. The purpose of this two-arm, 28-day, parallel-group, randomised, double-blind, placebo-controlled trial was to determine the effects of a topical curcumin gel (VAS-101) on knee pain and symptoms in adults with knee osteoarthritis. Methods Sixty adults aged 45–75 with knee osteoarthritis applied a curcumin or placebo gel to their knee, every second day for 28 days. Outcome measures comprised the Knee Injury and Osteoarthritis Outcome Score (KOOS), daily pain ratings, and several performance-based tests. Rescue oral medication intake was also monitored over time. Results Compared to the placebo, VAS-101 was associated with greater improvements in the KOOS pain score (primary outcome measure) (β: 5.12; 95% CI: 0.47, 9.77; d = 0.62, p = 0.041), and mean daily pain ratings (F 3, 225 = 4.42; d = 0.55, p = 0.005). In the VAS-101 group, 39.3% of participants reported feeling either much or very much improved, compared with 13.3% in the placebo group ( p = 0.019). Moreover, 32.1% of participants in the VAS-101 group achieved a Minimal Clinically Important Difference, compared to 13.3% in the placebo group, although this group difference was not statistically significant ( p = 0.086). There were no group differences in changes in other KOOS subscale scores or the performance-based tests. VAS-101 was well-tolerated, with no significant adverse reactions reported. However, skin staining was observed as expected with topical curcumin, which resolved 2–3 days after application ceased. Conclusions Conservative dosing of a topically applied curcumin-containing gel (VAS-101), administered every two days for 28 days, is associated with moderate reductions in knee pain in adults with knee osteoarthritis. Further investigations utilising larger sample sizes, longer treatment durations, and alternative treatment regimens will be important to identify how these factors affect treatment adherence, tolerance, and efficacy.