This study examined the efficacy and tolerability of duloxetine and venlafaxine extended-release (XR) treatment for generalized anxiety disorder (GAD), with a secondary focus on psychic and somatic symptoms within GAD.

The design was a 10-week, multi-center, double-blind placebo-controlled study of duloxetine (20 mg or 60–120 mg once daily) and venlafaxine XR (75–225 mg once daily) treatment. Efficacy was measured using the Hamilton Anxiety Rating Scale (HAMA), which includes psychic and somatic factor scores. Tolerability was measured by occurrence of treatment-emergent adverse events (TEAEs) and discontinuation rates.

Adult out-patients (mean age 42.8 years; 57.1% women) with DSM-IV-defined GAD were randomly assigned to placebo (n=170), duloxetine 20 mg (n=84), duloxetine 60–120 mg (n=158) or venlafaxine XR 75–225 mg (n=169) treatment. Each of the three active treatment groups had significantly greater improvements on HAMA total score from baseline to endpoint compared with placebo (p=0.01–0.001). For the HAMA psychic factor score, both duloxetine treatment arms and venlafaxine XR demonstrated significantly greater improvement compared with placebo (p=0.01–0.001). For the HAMA somatic factor score, the mean improvement in the duloxetine 60–120 mg and venlafaxine XR groups was significantly greater than placebo (p⩽0.05 and p⩽0.01 respectively), whose mean improvement did not differ from the duloxetine 20 mg group (p=0.07). Groups did not differ in study discontinuation rate due to adverse events.

Duloxetine and venlafaxine treatment were each efficacious for improvement of core psychic anxiety symptoms and associated somatic symptoms for adults with GAD.