In the never-ending hunt for effective pain relief, duloxetine (CYMBALTA, Eli Lilly), a SNRI, was recently considered by the TGA for its indications to include the treatment of either chronic somatic or chronic musculoskeletal pain.
SNRIs appear promising as analgesics through their enhanced inhibition of centrally sensitised descending pain pathways.
The TGA recognised that duloxetine was effective in some patients with chronic low back pain, but was concerned that in the five trials only placebo controls were used, with no comparison against active or investigation of combination therapies, and could not extrapolate outcomes from the narrow patient groups studied. The demonstrated clinical benefit did not justify patient exposure to the significant side effect profile of duloxetine in these patients.
They also found the term “somatic pain” is not used consistently, or defined well enough to be used in clinical practice.
With duloxetine’s current indication for treatment of Diabetic Peripheral Neuropathic Pain, approval in Canada and the USA for similar additional indications, and the recent approval by the TGA of a new SNRI, milnacipran, for management of fibromyalgia, we are likely to see more developments in this area.