In a new study, Cymbalta (duloxetine HCl) 60-120 mg, taken once daily, reduced pain severity significantly, compared with placebo, in patients with osteoarthritis pain of the knee. Data from the 13-week randomized, double-blind, placebo-controlled clinical trial were presented at the annual meeting of the American Academy of Pain Medicine (AAPM) in Honolulu, Hawaii.

Duloxetine-treated patients showed greater reductions from baseline on the primary endpoint, the 24-hour average pain score on the Brief Pain Inventory (BPI), compared with placebo-treated patients. In the study, 65 percent of duloxetine-treated patients experienced a clinically significant (at least 30 per cent) improvement in pain, compared with 44 per cent of placebo-treated patients.

The duloxetine-treated patients also showed improved physical function, compared with placebo-treated patients, as measured by the Western Ontario and McMaster Osteoarthritis Index (WOMAC). In this study, patients on duloxetine did not show statistically significant improvements on the WOMAC pain and stiffness subscales compared with placebo.

"The disabling nature of osteoarthritis pain can greatly impact a person's life," said Vladimir Skljarevski, a study author and medical fellow at Eli Lilly and Company. "As our population ages, osteoarthritis of the knee is likely to become an increasing problem."

The most common adverse events in the study (occurred at a rate of greater than or equal to 5 percent and at least twice the rate of placebo) included nausea, constipation and excessive sweating (hyperhidrosis). Adverse events were similar to those seen in previous duloxetine studies.

It is estimated that 27 million adults in the United States have osteoarthritis and the prevalence increases with age. Osteoarthritis of the knee is a common subtype of this disorder, impacting the lives of approximately 10 million Americans. In addition to pain, other symptoms of osteoarthritis include aching, stiffness and limited range of motion of the joint. Duloxetine is being studied to manage the pain associated with this disorder.

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