Effexor XR (Page 10 of 13)

14.3 Social Anxiety Disorder (also known as Social Phobia)

The efficacy of Effexor XR as a treatment for Social Anxiety Disorder (SAD) was established in four double-blind, parallel-group, 12-week, multicenter, placebo-controlled, flexible-dose studies (studies 1–4) and one double-blind, parallel-group, 6-month, placebo-controlled, fixed/flexible-dose study, which included doses in a range of 75 to 225 mg per day in adult outpatients meeting DSM-IV criteria for SAD (study 5).

In these five studies, Effexor XR was statistically significantly more effective than placebo on change from baseline to endpoint on the Liebowitz Social Anxiety Scale (LSAS) total score. There was no evidence for any greater effectiveness of the 150 to 225 mg per day group compared to the 75 mg per day group in the 6-month study.

Examination of subsets of the population studied did not reveal any differential responsiveness on the basis of gender. There was insufficient information to determine the effect of age or race on outcome in these studies.

Table 19: Social Anxiety Disorder Studies
Study Number Treatment Group Primary Efficacy Measure: LSAS Score
Mean Baseline Score (SD) LS Mean Change from Baseline (SE) Placebo Subtracted Difference * (95% CI)
SD: standard deviation; SE: standard error; LS Mean: least-squares mean; CI: confidence interval.* Doses statistically significantly superior to placebo.
*
Difference (drug minus placebo) in least-squares mean change from baseline
Study 1 Ven XR (75–225 mg) 91.1 -31.0(2.22) 11.2 (-5.3, -17.1)
Placebo 86.7 -19.9 (2.22)
Study 2 Ven XR (75–225 MG) 90.8 -32.8 (2.69) -10.7 (-3.7,-17.6)
Placebo 87.4 -22.1 (2.66)
Study 3 Ven XR (75–225 MG) 83.2 -36.0 (2.35) -16.9(-22.6, -11.2)
Placebo 83.6 -19.1 (2.40) -12.7 (-6.5, -19.0)
Study 4 Ven XR (75–225 mg) 86.2 -35.0 (2.64) -14.6 (-21.8, -7.4)
Placebo 86.1 -22.2 (2.47)
Study 5 Ven XR 75 mg 91.8 -38.1 (3.16) -14.6 (-21.8, -7.4)
Ven XR (150–225 mg) 86.2 -37.6 (3.05) -14.1 (-21.3, -6.9)
Placebo 89.3 -23.5 (3.08)

14.4 Panic Disorder

The efficacy of Effexor XR as a treatment for Panic Disorder (PD) was established in two double-blind, 12-week, multicenter, placebo-controlled studies in adult outpatients meeting DSM-IV criteria for PD, with or without agoraphobia. Patients received fixed doses of 75 or 150 mg per day in one study (study 1) and 75 or 225 mg per day in the other study (study 2).

Efficacy was assessed on the basis of outcomes in three variables: (1) percentage of patients free of full-symptom panic attacks on the Panic and Anticipatory Anxiety Scale (PAAS); (2) mean change from baseline to endpoint on the Panic Disorder Severity Scale (PDSS) total score; and (3) percentage of patients rated as responders (much improved or very much improved) on the Clinical Global Impressions (CGI) Improvement scale. In these two studies, Effexor XR was statistically significantly more effective than placebo (for each fixed dose) on all three endpoints, but a dose-response relationship was not clearly established.

Examination of subsets of the population studied did not reveal any differential responsiveness on the basis of gender. There was insufficient information to determine the effect of age or race on outcome in these studies.

In a longer term study (study 3), adult outpatients meeting DSM-IV criteria for PD who had responded during a 12-week open phase with Effexor XR (75 to 225 mg per day) were randomly assigned to continue the same Effexor XR dose (75, 150, or 225 mg) or switch to placebo for observation for relapse under double-blind conditions. Response during the open phase was defined as ≤ 1 full-symptom panic attack per week during the last 2 weeks of the open phase and a CGI Improvement score of 1 (very much improved) or 2 (much improved). Relapse during the double-blind phase was defined as having 2 or more full-symptom panic attacks per week for 2 consecutive weeks or having discontinued due to loss of effectiveness as determined by the investigators during the study. Randomized patients were in response status for a mean time of 34 days prior to being randomized. In the randomized phase following the 12-week open-label period, patients receiving continued Effexor XR experienced a statistically significantly longer time to relapse.

Table 20: Panic Disorder Studies:
Study Number Treatment Group Primary Efficacy Measure: Whether Free of Full-symptom Panic Attacks
Percent of patients Free of Full symptom panic attack Adjusted Odds Ratio * to placebo Adjusted Odds Ratio * 95% Confidence Interval
*
Odds ratio (drug to placebo) in terms of probability of free of full-symptom panic attacks based on logistic regression model.95%CI: 95% confidence interval without adjusting for multiple dose arms.
Doses statistically significantly superior to placebo.
Study 1 Ven XR 75 mg 54.1% (85/157) 2. 268 (1.43, 3.59)
Ven XR 150 mg 61.4% (97/158) 3.035 (1.91, 4.82)
Placebo 34.4% (53/154)
Study 2 Ven XR 75 mg 64.1% (100/156) 2.350 (1.46, 3.78)
Ven XR 225 mg 70.0% (112/160) 2.890 (1.80, 4.64)
Placebo 46.5% (73/157)

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