Christine J. Guico-Pabia

Cytochrome P450 2D6 phenotype predicts antidepressant efficacy of venlafaxine: a secondary analysis of 4 studies in major depressive disorder.

INTRODUCTION Venlafaxine, a serotonin-norepinephrine reuptake inhibitor antidepressant, is metabolized primarily by the cytochrome P450 2D6 enzyme into O-desmethylvenlafaxine (ODV). The ODV/venlafaxine ratio can be used to distinguish between extensive metabolizers (EMs) and poor metabolizers (PMs). OBJECTIVES To determine the relative efficacy and tolerability of venlafaxine in EM vs PM patients with major depressive disorder (MDD). METHOD Data from 4 double-blind, placebo-controlled studies of patients with MDD were pooled. Blood samples were analyzed for plasma concentrations of venlafaxine, ODV, total venlafaxine + ODV, and ODV/venlafaxine ratio. Patients were classified as EMs or PMs on the basis of ODV/venlafaxine ratios. Changes from baseline in depression scale scores were compared between EMs and PMs using t tests. Rates of response, remission, discontinuation, and adverse events (AEs) were compared for EMs and PMs using Fisher exact tests. RESULTS Compared with PMs, EMs had significantly greater mean changes from baseline on 4 of 5 depression rating scales (all 4 comparisons, P ≤ .020). A significantly greater percentage of EMs achieved response or remission by most measures compared with PMs (4 of 5 comparisons, P ≤ .015). Rates of discontinuation and AEs did not differ significantly between EMs and PMs. Since there were no substantial differences between EMs and PMs in terms of venlafaxine dose or tolerability, these factors are not likely to account for the efficacy findings. CONCLUSIONS Venlafaxine treatment in EMs was associated with greater efficacy in MDD on virtually all measures compared with PMs, with no important tolerability differences.

An Integrated Analysis of the Efficacy of Desvenlafaxine Compared with Placebo in Patients with Major Depressive Disorder

INTRODUCTION To assess the efficacy of desvenlafaxine (administered as desvenlafaxine succinate) in outpatients with major depressive disorder. METHODS A meta-analysis of individual patient data was performed on the complete set of registration trials (nine randomized, double-blind, placebo-controlled 8-week studies) of desvenlafaxine. Patients received fixed (50, 100, 200, or 400 mg/day; n=1,342) or flexible doses (100-400 mg/day; n=463) of desvenlafaxine or placebo (n=1,108). The primary efficacy variable was the 17-item Hamilton Rating Scale for Depression (HAM-D(17)); the primary intent to treat analyses used the last-observation-carried-forward method. RESULTS Significantly greater improvement with desvenlafaxine versus placebo on the HAM-D(17) total score was observed for the full data set (difference in adjusted means: -1.9; P<.001), each fixed-dose group (all P<.001), and the flexible-dose group (P=.024). Overall rates of HAM-D1(17) response (> or =150% decrease from baseline score: 53% vs 41%) and remission (HAM-D(17) < or =7: 32% vs 23%) were significantly greater for desvenlafaxine versus placebo (all P<.001). Discontinuation rates due to adverse events increased with dose (4% to 18%; placebo: 3%). CONCLUSION Desvenlafaxine demonstrated short-term efficacy for treating major depressive disorder across the range of doses studied. No evidence of greater efficacy was observed with doses >50 mg/day; a strong dose-response effect on tolerability was observed.

Symptomatic and functional improvement in employed depressed patients: a double-blind clinical trial of desvenlafaxine versus placebo.

Objective: This is the first study to assess the efficacy of desvenlafaxine (administered as desvenlafaxine succinate) for improving depressive symptoms and functioning exclusively in employed patients with major depressive disorder (MDD). Methods: Gainfully employed (≥20 h/wk) male and female outpatients with MDD were randomly assigned (2:1 ratio) to 12 weeks of double-blind treatment with desvenlafaxine 50 mg/d or placebo. Analysis of covariance was used to compare differences in week 12 adjusted mean changes from baseline on the 17-item Hamilton Depression Rating Scale (HAM-D17) (primary outcome) and Sheehan Disability Scale (SDS) (key secondary outcome) in the intent-to-treat (ITT) population. A predefined, modified ITT population (ie, those in the ITT population with baseline HAM-D17 ≥20) was also analyzed. Tolerability was assessed by recording adverse events and change on the Arizona Sexual Experience Scale. Results: Baseline HAM-D17 scores for desvenlafaxine (n = 285) and placebo (n = 142) were 22.0 and 21.8, whereas baseline SDS scores were 19.8 and 20.4. Adjusted mean differences between desvenlafaxine and placebo were 2.1 (95% confidence interval [CI], 0.78-3.46; P = 0.002) on the HAM-D17 and 1.3 (95% CI, −0.09 to 2.76; P = 0.067) on the SDS. For the modified ITT sample, desvenlafaxine (n = 208) and placebo (n = 102), baseline HAM-D17 scores were 23.8 and 23.9; the SDS baseline scores were 20.1 and 20.8. Mean differences were 2.6 (95% CI, 0.93-4.22; P = 0.002) on the HAM-D17 and 2.1 (95% CI, 0.36-3.76; P = 0.017) on the SDS. Adverse events and Arizona Sexual Experience Scale scores were comparable between groups. Conclusions: Desvenlafaxine 50 mg/d was efficacious for treating MDD in gainfully employed adults. Between-group differences on the SDS narrowly missed statistical significance in the ITT population alone, but the totality of data suggests functional improvements with active treatment.

An integrated analysis of the safety and tolerability of desvenlafaxine compared with placebo in the treatment of major depressive disorder

INTRODUCTION The safety and tolerability profiles of antidepressants can often influence the treatment choices of clinicians treating major depressive disorder. The purpose of this investigation was to characterize the safety and tolerability of desvenlafaxine (administered as desvenlafaxine succinate) in treating depression. METHODS An integrated analysis of all short-term, randomized, double-blind, placebo-controlled registration studies for major depressive disorder (four flexible-dose and five fixed-dose studies) was performed. Adult outpatients with major depressive disorder received desvenlafaxine doses ranging from 50-400 mg/day or placebo for 8 weeks. Treatment-emergent adverse events, laboratory values, vital signs, and discontinuation symptoms were evaluated. In the subset of fixed-dose studies, dose-related effects were analyzed. RESULTS In the overall population (placebo: n=1,116; desvenlafaxine: n=1,834), adverse events resulted in discontinuations in 3% of placebo-treated patients and 12% of desvenlafaxine-treated patients; in the subset of fixed-dose studies, the rates were 4% with placebo and increased with desvenlafaxine dose (50 mg/day: 4%; 400 mg/day: 18%). The most common treatment-emergent adverse event was transient nausea that was generally mild to moderate. The most common sexual dysfunction associated with desvenlafaxine treatment was erectile dysfunction in men (7% vs 1% with placebo) and anorgasmia in women (1% and 0%). One desvenlafaxine-treated patient died of a completed suicide; there were four suicide attempts (three desvenlafaxine, one placebo) and eight cases of suicidal ideation (five desvenlafaxine, three placebo) during the on-therapy period. Small but statistically significant changes in mean blood pressure occurred at all desvenlafaxine doses; clinically meaningful changes were observed in 1% of placebo-treated patients and 2% of desvenlafaxine-treated patients. Desvenlafaxine was associated with small but statistically significant mean changes in laboratory assessments, particularly lipid and liver enzyme elevations, and electrocardiograms; few cases of these changes were clinically relevant. CONCLUSION Desvenlafaxine in the treatment of major depressive disorder exhibited a safety and tolerability profile generally consistent with the serotonin-norepinephrine reuptake inhibitor class. The most common adverse event was transient nausea. At the recommended therapeutic dose of 50 mg/day, discontinuation due to adverse events was similar to placebo.

Venlafaxine metabolism as a marker of cytochrome P450 enzyme 2D6 metabolizer status.

Introduction: One of the major enzymes of the cytochrome P450 drug-metabolizing system, CYP2D6, shows a high degree of genetic polymorphism and variability in activity. Based on the degree of CYP2D6 activity, individuals can be broadly classified as poor metabolizers (PMs) or extensive metabolizers (EMs); the metabolism of CYP2D6 substrates differs among PMs and EMs. The metabolism of various drugs that are substrates of CYP2D6 has been used as a marker for metabolic phenotype, calculating the plasma or urinary metabolic ratio of the parent compound to its metabolite. The current analysis evaluates the use of the O-desmethylvenlafaxine-venlafaxine ratio (ODV/VEN) after administration of VEN, a CYP2D6 substrate, for determining CYP2D6 metabolic phenotype in healthy adults receiving VEN. Methods: The analysis included data from 2 studies in which healthy adults were classified as either EMs or PMs using established methods (1 genotypic and 1 phenotypic) and were then administered VEN at daily dosages ranging from 75 to 150 mg. Blood plasma samples were taken at various time points, and the ODV/VEN ratio was calculated. Results: Blood samples from 28 participants in the 2 studies were available for analysis. The ODV/VEN ratio distinguished the EM and PM phenotypes; ratios were 1 or greater for EMs and less than 1 for PMs at 4 hours after dose administration. Conclusions: The ratio of ODV/VEN is an effective means of phenotyping individuals according to their CYP2D6 metabolizer status.

Assessing the efficacy of desvenlafaxine for improving functioning and well-being outcome measures in patients with major depressive disorder: a pooled analysis of 9 double-blind, placebo-controlled, 8-week clinical trials.

OBJECTIVE To evaluate the effects of desvenlafaxine therapy on functioning and well-being in major depressive disorder (MDD). METHOD Total and individual item Sheehan Disability Scale (SDS) and 5-item World Health Organization Well-Being Index (WHO-5) scores from 8 double-blind, placebo-controlled, 8-week desvenlafaxine clinical trials were pooled. Scores on the 17-item Hamilton Depression Rating Scale (HDRS(17)) work/activities and Montgomery-Asberg Depression Rating Scale (MADRS) lassitude items were pooled from 9 studies. Outpatients with DSM-IV MDD were randomly assigned to fixed (5 studies; 50, 100, 200, or 400 mg/d; n = 1,342) or flexible (4 studies, 100-400 mg/d; n = 463) doses of desvenlafaxine or placebo (n = 1,108). Data from each patients final evaluation were analyzed for the total population and for individual dose groups from the fixed-dose studies and were compared between groups using analysis of covariance. RESULTS Compared with placebo, desvenlafaxine therapy resulted in significantly greater improvements in SDS total score (-2.0) and individual items regarding work (-0.6), social life/leisure activities (-0.8), and family life/home responsibilities (-0.7; P < .001 for all comparisons), as well as WHO-5 total score (1.7) and individual items (good spirits [0.4], calm/relaxed [0.4], active/vigorous [0.3], fresh/rested [0.3], and interest [0.3]; P < .001 for all comparisons). Desvenlafaxine treatment resulted in significant improvements on the HDRS(17) work/activities (-0.2; P < .001) and MADRS lassitude (-0.3; P < .001) items compared with placebo. Significant differences were observed for the individual fixed-dose groups on all outcomes (P < .05); there was no evidence of a dose-response relationship. CONCLUSIONS Desvenlafaxine therapy resulted in significant improvements in the functioning and well-being among MDD patients.

A Meta-analysis of Factors Impacting Detection of Antidepressant Efficacy in Clinical Trials: The Importance of Academic Sites

Variability in placebo response greatly complicates the design, conduct, and interpretation of clinical trials of antidepressant medications. To identify factors that impact detection of antidepressant–placebo differences, we conducted a meta-analysis of all relevant phase II–IV clinical trials for major depressive disorder conducted by the manufacturer of venlafaxine and desvenlafaxine completed by March 2011. We examined 15 factors potentially relevant to trial outcomes, using the standardized mean difference on the Hamilton Rating Scale for Depression (HAM-D17) score as the primary outcome. Thirty trials comprising 8933 patients were included. In univariate analyses, antidepressant efficacy (ie, drug vs placebo difference) was predicted most strongly (β=3.74, p=0.0002) by the proportion of patients in the trial enrolled from academic sites. Other factors predicting larger drug–placebo differences included lower participant completion rate, fewer post-baseline study visits, earlier year of study, and study drug (venlafaxine>desvenlafaxine). In multivariate meta-regression modeling, only the proportion of patients from academic sites maintained statistical significance as a predictor of drug–placebo separation for both HAM-D17 continuous score change (β=2.24, p=0.034) and response rate (β=2.26, p=0.035). Including a higher proportion of academic sites may increase the ability to detect differences between active drug and placebo in clinical trials of major depressive disorder.

Desvenlafaxine and escitalopram for the treatment of postmenopausal women with major depressive disorder.

Objective:This study assessed the efficacy, safety, and tolerability of the serotonin-norepinephrine reuptake inhibitor desvenlafaxine and the selective serotonin reuptake inhibitor escitalopram for major depressive disorder (MDD) in postmenopausal women. Methods:In this randomized, double-blind study, postmenopausal outpatients (aged 40-70 y) with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition MDD received flexible-dose desvenlafaxine (100-200 mg/d) or escitalopram (10-20 mg/d) for 8 weeks. Acute-phase responders, that is, women with a 50% or greater reduction from baseline in the 17-item Hamilton Rating Scale for Depression (HAM-D17) total score, were eligible to continue the same double-blind treatment in the 6-month continuation phase. The primary efficacy outcomes were mean change from baseline in HAM-D17 total score (acute phase), analyzed using a mixed-effects model for repeated measures, and the proportion of women who maintained response (continuation phase), analyzed using logistic regression. Results:Reductions in HAM-D17 total score at acute-phase endpoint were similar for desvenlafaxine- and escitalopram-treated women (−13.6 vs −14.3, respectively; P = 0.24). No significant difference was observed between groups at continuation-phase endpoint in the proportion of women who maintained response (desvenlafaxine, 82%; escitalopram, 80%; P = 0.70). In both phases, desvenlafaxine and escitalopram were generally safe and well tolerated. Conclusions:Among postmenopausal outpatients with MDD, there were no significant differences in the efficacy of desvenlafaxine and escitalopram based on primary efficacy analyses. The results do not support the overall hypothesis that the serotonin-norepinephrine reuptake inhibitor desvenlafaxine has an efficacy advantage for the treatment of MDD in postmenopausal women because, in this particular subgroup, desvenlafaxine failed to prove superiority over escitalopram. Safety and tolerability were comparable.

Assessing the relationship between functional impairment/recovery and depression severity: a pooled analysis.

The objective of this study was to explore the relationship between assessments of functional impairment, emotional well-being, and depression symptoms. Data were pooled from 3530 outpatients with major depressive disorder enrolled in 10 desvenlafaxine clinical trials. The primary outcome measures included (a) the 17-item Hamilton Rating Scale for Depression (HAM-D17) as a measure of depressive symptom severity and (b) the Sheehan Disability Scale (SDS) and five-item World Health Organization Well-Being Index (WHO-5) as measures of functional impairment and well-being. A linear regression model was used to identify the SDS and WHO-5 values that equate to the predetermined clinically relevant three-point difference between active treatment and placebo on the HAM-D17. A receiver operating characteristic analysis was conducted to determine the SDS score that equates to a remission of depression symptoms (i.e. HAM-D17 ⩽7). An approximate three-point difference between active treatment and placebo on the SDS (2.8) and WHO-5 (2.5) was determined to be clinically relevant in relation to improvements in depressive symptoms. An SDS of less than or equal to 7 was equivalent to a remission of depression symptoms, providing a definition of functional remission. A better understanding of the relationship between depressive symptoms and functional impairment and well-being may provide clinicians with a more comprehensive means of assessing treatment effects in major depressive disorder.

Improving Quality of Depression Care Using Organized Systems of Care: A Review of the Literature

OBJECTIVE To establish the need for a chronic disease management strategy for major depressive disorder (MDD), discuss the challenges involved in implementing guideline-level treatment for MDD, and provide examples of successful implementation of collaborative care programs. DATA SOURCES A systematic literature search of MEDLINE and the US National Library of Medicine was performed. STUDY SELECTION We reviewed clinical studies evaluating the effectiveness of collaborative care interventions for the treatment of depression in the primary care setting using the keywords collaborative care, depression, and MDD. This review includes 45 articles relevant to MDD and collaborative care published through May 2010 and excludes all non-English-language articles. RESULTS Collaborative care interventions include a greater role for nonmedical specialists and a supervising psychiatrist with the major goal of improving quality of depression care in primary care systems. Collaborative care programs restructure clinical practice to include a patient care strategy with specific goals and an implementation plan, support for self-management training, sustained patient follow-up, and decision support for medication changes. Key components associated with the most effective collaborative care programs were improvement in antidepressant adherence, use of depression case managers, and regular case load supervision by a psychiatrist. Across studies, primary care patients randomized to collaborative care interventions experienced enhanced treatment outcomes compared with those randomized to usual care, with overall outcome differences approaching 30%. CONCLUSIONS Collaborative care interventions may help to achieve successful, guideline-level treatment outcomes for primary care patients with MDD. Potential benefits of collaborative care strategies include reduced financial burden of illness, increased treatment adherence, and long-term improvement in depression symptoms and functional outcomes.