Duloxetine (Page 14 of 18)

14.2 Generalized Anxiety Disorder

The efficacy of duloxetine delayed-release capsules in the treatment of generalized anxiety disorder (GAD) was established in 1 fixed-dose randomized, double-blind, placebo-controlled trial and 2 flexible-dose randomized, double-blind, placebo-controlled trials in adult outpatients between 18 and 83 years of age meeting the DSM-IV criteria for GAD.

In 1 flexible-dose study and in the fixed-dose study, the starting dose was 60 mg once daily where down titration to 30 mg once daily was allowed for tolerability reasons before increasing it to 60 mg once daily. Fifteen percent of patients were down titrated. One flexible-dose study had a starting dose of 30 mg once daily for 1 week before increasing it to 60 mg once daily.

The 2 flexible-dose studies involved dose titration with duloxetine delayed-release capsules doses ranging from 60 mg once daily to 120 mg once daily (N=168 and N=162) compared to placebo (N=159 and N=161) over a 10-week treatment period. The mean dose for completers at endpoint in the flexible-dose studies was 104.75 mg/day. The fixed-dose study evaluated duloxetine delayed-release capsules doses of 60 mg once daily (N=168) and 120 mg once daily (N=170) compared to placebo (N=175) over a 9-week treatment period. While a 120 mg/day dose was shown to be effective, there is no evidence that doses greater than 60 mg/day confer additional benefit.

In all 3 studies, duloxetine delayed-release capsules demonstrated superiority over placebo as measured by greater improvement in the Hamilton Anxiety Scale (HAM-A) total score (Studies 1 to 3 in Table 8) and by the Sheehan Disability Scale (SDS) global functional impairment score. The SDS is a composite measurement of the extent emotional symptoms disrupt patient functioning in 3 life domains: work/school, social life/leisure activities, and family life/home responsibilities.

In another study, 887 patients meeting DSM-IV-TR criteria for GAD received duloxetine delayed-release capsules 60 mg to 120 mg once daily during an initial 26-week open-label treatment phase. Four hundred and twenty-nine patients who responded to open-label treatment (defined as meeting the following criteria at weeks 24 and 26: a decrease from baseline HAM-A total score by at least 50% to a score no higher than 11, and a Clinical Global Impressions of Improvement [CGI-Improvement] score of 1 or 2) were randomly assigned to continuation of duloxetine delayed-release capsules at the same dose (N=216) or to placebo (N=213) and were observed for relapse. Of the patients randomized, 73% had been in a responder status for at least 10 weeks. Relapse was defined as an increase in CGI-Severity score at least 2 points to a score ≥4 and a MINI (Mini-International Neuropsychiatric Interview) diagnosis of GAD (excluding duration), or discontinuation due to lack of efficacy. Patients taking duloxetine delayed-release capsules experienced a statistically significantly longer time to relapse of GAD than did patients taking placebo (Study 4 in Figure 2).

Subgroup analyses did not indicate that there were any differences in treatment outcomes as a function of age or gender.

  1. Table 8: Summary of the Primary Efficacy Results for Studies in General Anxiety Disorder
SD: standard deviation; SE: standard error; LS Mean: least-squares mean; CI: confidence interval, not adjusted for multiplicity in trials where multiple dose groups were included. a Difference (drug minus placebo) in least squares mean change from baseline. b Dose statistically significantly superior to placebo.

Study Number

Treatment Group

Primary Efficacy Measure

Mean Baseline Score (SD)

LS Mean Change from Baseline (SE)

Placebo-subtracted Difference a (95% CI)

Study 1 (HAM-A)

Duloxetine delayed-release capsules (60 mg/day) b

25.1 (7.18)

-12.8 (0.68)

-4.4 (-6.2, -2.5)

Duloxetine delayed-release capsules (120 mg/day) b

25.1 (7.24)

-12.5 (0.67)

-4.1 (-5.9, -2.3)

Placebo

25.8 (7.66)

-8.4 (0.67)

Study 2 (HAM-A)

Duloxetine delayed-release capsules (60 to 120 mg/day) b

22.5 (7.44)

-8.1 (0.7)

-2.2 (-4.2, -0.3)

Placebo

23.5 (7.91)

-5.9 (0.7)

Study 3 (HAM-A)

Duloxetine delayed-release capsules (60 to 120 mg/day) b

25.8 (5.66)

-11.8 (0.69)

-2.6 (-4.5, -0.7)

Placebo

25 (5.82)

-9.2 (0.67)


Figure 2: Kaplan-Meier Estimation of Cumulative Proportion of Patients with Relapse (GAD Study 4)

Figure 2: Kaplan-Meier Estimation of Cumulative Proportion of Patients with Relapse (GAD Study 4)
(click image for full-size original)

Pediatric use information for patients ages 7 to 17 years is approved for Eli Lilly and Company, Inc.’s duloxetine delayed-release capsules. However, due to Eli Lilly and Company, Inc.’s marketing exclusivity rights, this drug product is not labeled with that pediatric information.

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