Estimates of serotonin and norepinephrine transporter inhibition in depressed patients treated with paroxetine or venlafaxine.

Paroxetine and venlafaxine are potent serotonin transporter (SERT) antagonists and weaker norepinephrine transporter (NET) antagonists. However, the relative magnitude of effect at each of these sites during treatment is unknown. Using a novel blood assay that estimates CNS transporter occupancy we estimated the relative SERT and NET occupancy of paroxetine and venlafaxine in human subjects to assess the relative magnitude of SERT and NET inhibition. Outpatient subjects (N=86) meeting criteria for major depression were enrolled in a multicenter, 8 week, randomized, double-blind, parallel group, antidepressant treatment study. Subjects were treated by forced-titration of paroxetine CR (12.5-75 mg/day) or venlafaxine XR (75-375 mg/day) over 8 weeks. Blood samples were collected weekly to estimate transporter inhibition. Both medications produced dose-dependent inhibition of the SERT and NET. Maximal SERT inhibition at week 8 for paroxetine and venlafaxine was 90% (SD 7) and 85% (SD 10), respectively. Maximal NET inhibition for paroxetine and venlafaxine at week 8 was 36% (SD 19) and 60% (SD 13), respectively. The adjusted mean change from baseline (mean 28.6) at week 8 LOCF in MADRS total score was -16.7 (SE 8.59) and -17.3 (SE 8.99) for the paroxetine and venlafaxine-treated patients, respectively. The magnitudes of the antidepressant effects were not significantly different from each other (95%CI -3.42, 4.54, p=0.784). The results clearly demonstrate that paroxetine and venlafaxine are potent SERT antagonists and less potent NET antagonists in vivo. NET antagonism has been posited to contribute to the antidepressant effects of these compounds. The clinical significance of the magnitude of NET antagonism by both medications remains unclear at present.

The efficacy and safety of aripiprazole as adjunctive therapy in major depressive disorder: a second multicenter, randomized, double-blind, placebo-controlled study.

Nonresponse to one or more antidepressants is common and an important public health problem. This study evaluated the efficacy and safety of adjunctive aripiprazole or placebo to standard antidepressant therapy (ADT) in patients with major depressive disorder who showed an inadequate response to at least 1 and up to 3 historical and 1 additional prospective ADT. The study comprised a 7-28-day screening, an 8-week prospective treatment, and a 6-week randomization phase. During prospective treatment, patients experiencing a major depressive episode (17-item Hamilton Rating Scale for Depression total score > or = 18) received single-blind adjunctive placebo plus clinicians' choice of ADT (escitalopram, fluoxetine, paroxetine controlled-release, sertraline, or venlafaxine extended-release). Subjects with inadequate response were randomized to adjunctive placebo (n = 190) or adjunctive aripiprazole (n = 191) (starting dose 5 mg/d, dose adjustments 2-20 mg/d, mean end-point dose of 11.0 mg/d). The primary efficacy endpoint was the mean change in Montgomery-Asberg Depression Rating Scale total score from end of prospective treatment phase to end of randomized treatment phase (last observation carried forward). Mean change in Montgomery-Asberg Depression Rating Scale total score was significantly greater with adjunctive aripiprazole than placebo (-8.5 vs -5.7; P = 0.001). Remission rates were significantly greater with adjunctive aripiprazole than placebo (25.4% vs 15.2%; P = 0.016) as were response rates (32.4% vs 17.4%; P < 0.001). Adverse events occurring in 10% of patients or more with adjunctive placebo or aripiprazole were akathisia (4.2% vs 25.9%), headache (10.5% vs 9.0%), and fatigue (3.7% vs 10.1%). Incidence of adverse events leading to discontinuation was low (adjunctive placebo [1.1%] vs adjunctive aripiprazole [3.7%]). Aripiprazole is an effective and safe adjunctive therapy as demonstrated in this short-term study for patients who are nonresponsive to standard ADT.

Aripiprazole augmentation of antidepressants for the treatment of partially responding and nonresponding patients with major depressive disorder.

OBJECTIVE: To determine the efficacy and tolerability of aripiprazole, a dopamine D2 and 5-HT1A receptor partial agonist, as augmentation of antidepressant treatment of partially responding and nonresponding patients with major depressive disorder. METHOD: Fifteen patients with major depressive disorder (diagnosed with a site-generated form described in the text) and an incomplete response or no response to > or = 8 weeks of antidepressant (selective serotonin reuptake inhibitor, venlafaxine, or bupropion) monotherapy were treated with aripiprazole augmentation in an 8-week, open-label study. Data were gathered from July 2003 to March 2004. RESULTS: The mean duration of antidepressant monotherapy at baseline was 43.1 weeks. At baseline, mean Clinical Global Impressions-Severity of Illness scale and Hamilton Rating Scale for Depression (HAM-D) scores were 4.3 and 18.9, respectively. After initiation of aripiprazole augmentation, 6 of 15 patients achieved remission (HAM-D score < or = 7) at week 1, and 9 of 15 patients remitted by week 2. All 8 completers achieved remission by study endpoint. Akathisia in 2 patients who withdrew prematurely prompted a reduction in the starting dose of aripiprazole from 10 mg/day to 2.5 mg/day, resulting in a 50% reduction in attrition due to akathisia (2/7 withdrew due to akathisia with the 10-mg starting dose, 1/8 withdrew due to akathisia with the 2.5-mg starting dose). Discontinuation rates after 4 weeks of treatment were lower for the 2.5-mg starting dose (1/8 patients) than for the 10-mg starting dose (3/7 patients). Overall discontinuation rates at endpoint were lower for the 2.5-mg dose (3/8 patients) than the 10-mg dose (4/7 patients). Response to aripiprazole augmentation did not appear to be related to the antidepressant used at study initiation. CONCLUSION: Aripiprazole is an effective augmentation strategy for improving therapeutic response in patients with treatment-resistant major depressive disorder when administered in combination with standard antidepressant therapy. Based on this clinical signal, a double-blind, placebo-controlled trial is warranted.

Extended-release venlafaxine in relapse prevention for patients with major depressive disorder.

Many studies have demonstrated that venlafaxine is an efficacious and safe treatment for major depressive disorder (MDD). This double-blind, placebo-controlled study was performed to evaluate the efficacy of venlafaxine extended-release (XR) (75-225 mg/day) in the prevention of relapse of depression. Patients with MDD who responded to an 8-week course of venlafaxine XR treatment, i.e., had a score < or = 3 on the Clinical Global Impressions scale-Severity of Illness item (CGI-S) and a 21-item Hamilton Rating Scale for Depression (HAM-D(21)) score < or = 10, were randomly assigned to receive continuation treatment (up to 6 months) with venlafaxine XR (n=161) or placebo (n=157). The main efficacy outcome measure was the number of patients who experienced a relapse of depression. Relapse was defined by either a combination of a patient meeting Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for MDD and a CGI-S score > or = 4, two consecutive CGI-S scores > or = 4, or a final CGI-S score > or = 4 for a patient who withdrew from the study. The cumulative probability of relapse was calculated using the Kaplan-Meier method of survival analysis. During the 6-month evaluation period, significantly more patients in the placebo group had a relapse of MDD than did patients who continued treatment with venlafaxine XR. Cumulative relapse rates at 3 and 6 months were 19 and 28%, respectively, for venlafaxine XR, and 44 and 52%, respectively, for placebo. This study demonstrates that venlafaxine XR is an effective and safe continuation therapy.