In a new study, 60 mg of Cymbalta (duloxetine HCl) taken once daily significantly reduced chronic low back pain, as measured by the Brief Pain Inventory (BPI) average pain rating, compared with placebo. The data were presented at the annual meeting of the American Academy of Pain Medicine (AAPM) in San Antonio, Texas.

A total of 401 patients participated in the 12-week, double-blind, placebo-controlled study, designed to assess the efficacy of duloxetine 60 mg once daily on the reduction of pain severity in patients with chronic low back pain. In the study, duloxetine-treated patients experienced a statistically significantly greater improvement on BPI average pain scale compared with placebo in chronic low back pain (p<0.005).

The most common adverse events (those occurring in more than five per cent of study participants) in duloxetine-treated patients were nausea, headache, dry mouth, constipation and dizziness. A total of 41 patients in the study discontinued due to adverse events - 30 in the duloxetine-treated group and 11 in the placebo-treated group. Adverse events were similar to those seen in previous duloxetine studies.

"Chronic low back pain affects a significant number of people. In fact, research suggests that the incidence of the condition may be as high as 48 per cent," said Vladimir Skljarevski, lead study author and a neurologist and senior medical director at Lilly Research Laboratories.

According to the International Association for the Study of Pain (IASP), pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. Chronic pain is defined as pain that persists beyond acute pain or beyond the expected time for an injury to heal.

Serotonin and norepinephrine in the brain and spinal cord are believed to both mediate core mood symptoms and help regulate the perception of pain.