GAD Trials in Adults (Including Geriatric Patients)
The efficacy of duloxetine 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 (Studies GAD-1, GAD-2, and GAD-3, respectively).
In Studies GAD-1 and GAD-2, the starting dose was 60 mg once daily (down titration to 30 mg once daily was allowed for tolerability reasons; the dosage could be increased to 60 mg once daily). Fifteen percent of patients were down titrated. Study GAD-3 had a starting dose of 30 mg once daily for 1 week before increasing it to 60 mg once daily.
Studies GAD-2 and GAD-3 involved dose titration with duloxetine 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 dosage for completers at endpoint in these trials was 104.8 mg/day. Study GAD-1 evaluated duloxetine dosages 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 trials, duloxetine demonstrated superiority over placebo as measured by greater improvement in the Hamilton Anxiety Scale (HAM-A) total score (see 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 Study GAD-4, 887 patients meeting DSM-IV-TR criteria for GAD received duloxetine 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 at the same dosage (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 experienced a statistically significantly longer time to relapse of GAD than did patients taking placebo (see Figure 2).
Subgroup analyses did not indicate that there were any differences in treatment outcomes as a function of age or gender.
GAD Trial in Geriatric Patients
The efficacy of duloxetine in the treatment of patients ≥65 years of age with GAD was established in one 10-week flexible-dose, randomized, double-blind, placebo-controlled trial in adults ≥65 years of age meeting the DSM-IV criteria for GAD (Study GAD-5). In Study GAD-5, the starting dose was 30 mg once daily for 2 weeks before further dose increases in 30 mg increments at treatment weeks 2, 4, and 7 up to 120 mg once daily were allowed based on investigator judgment of clinical response and tolerability. The mean dosage for patients completing the 10-week acute treatment phase was 51 mg. Patients treated with duloxetine (N=151) demonstrated significantly greater improvement compared with placebo (N=140) on mean change from baseline to endpoint as measured by the HAM-A total score (see Table 8).
GAD Trial in Pediatric Patients 7 to 17 Years Old
The efficacy of duloxetine in the treatment of pediatric patients 7 to 17 years of age with GAD was established in 1 flexible-dose randomized, double-blind, placebo-controlled trial in pediatric outpatients with GAD (based on DSM-IV criteria) (Study GAD-6).
In Study GAD-6, the starting dosage was 30 mg once daily for 2 weeks. Further dosage increases in 30 mg increments up to 120 mg once daily were allowed based on investigator judgment of clinical response and tolerability. The mean dosage for patients completing the 10-week treatment phase was 57.6 mg/day. In this study, duloxetine (N=135) demonstrated superiority over placebo (N=137) from baseline to endpoint as measured by greater improvement in the Pediatric Anxiety Rating Scale (PARS) for GAD severity score (see Table 9).
Table 9: Summary of the Primary Efficacy Results for GAD Trials
|Study Number (population) (measurement)||Treatment Group||Primary Efficacy Measure|
|Mean Baseline Score (SD)||LS Mean Change from Baseline (SE)||Placebo-Subtracted Difference a (95% CI)|
|Study GAD-1 (Adult) (HAM-A)||Duloxetine (60 mg/day) b||25.1 (7.18)||-12.8 (0.68)||-4.4 (-6.2, -2.5)|
|Duloxetine (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 GAD-2 (Adult) (HAM-A)||Duloxetine (60-120 mg/day) b||22.5 (7.44)||-8.1 (0.70)||-2.2 (-4.2, -0.3)|
|Placebo||23.5 (7.91)||-5.9 (0.70)||—|
|Study GAD-3 (Adult) (HAM-A)||Duloxetine (60-120 mg/day) b||25.8 (5.66)||-11.8 (0.69)||-2.6 (-4.5, -0.7)|
|Placebo||25.0 (5.82)||-9.2 (0.67)||—|
|Study GAD-5 (Geriatric) (HAM-A)||Duloxetine (60-120 mg/day) b||24.6 (6.21)||-15.9 (0.63)||-4.2 (-5.9, -2.5)|
|Placebo||24.5 (7.05)||-11.7 (0.67)||—|
|Study GAD-6 (Pediatric) (PARS for GAD)||Duloxetine (30-120 mg/day) b||17.5 (1.98)||-9.7 (0.50)||-2.7 (-4.0, -1.3)|
|Placebo||17.4 (2.24)||-7.1 (0.50)||—|
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.
Figure 2: Cumulative Proportion a of Adult Patients with GAD Relapse (Study GAD-4)
a Kaplan-Meier estimator method.
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