Why carry out this study?

Topical non-steroidal anti-inflammatory drugs (NSAIDs) are frequently used to reduce pain and inflammation in the treatment of common recurring pain conditions (such as acute back or neck pain), with fewer systemic side effects and drug interactions compared with oral NSAIDs.

Diclofenac and capsaicin have different pharmacodynamic properties and may have complementary mechanisms of action, although a combination product has not yet been tested.

This double-blind clinical study assessed efficacy and tolerability of a topical combination of capsaicin + diclofenac versus gels with diclofenac alone, capsaicin alone, and placebo in the treatment of acute lower back or neck pain.

What was learned from the study?

The change in the level of pain between baseline and day 2 evening, 1 h after drug application, demonstrates superiority of the combination (− 3.05 cm) versus diclofenac alone (− 2.33 cm) and placebo (− 2.45 cm), but not capsaicin alone (− 3.26 cm).

Capsaicin alone and capsaicin + diclofenac showed superior benefit compared with placebo.

However, diclofenac alone demonstrated efficacy comparable with placebo, and therefore its addition to capsaicin added no increased pain relief over capsaicin alone.