Pharmacodynamic differences among patients due to variant 5-HT(2A) receptors appear to be more important than pharmacokinetic variation in determining paroxetine intolerance. Pharmacogenetic markers may be useful in predicting antidepressant treatment outcome.

These results support the hypothesis that the S allele of 5HTTLPR at the SLC6A4 locus is associated with a poor outcome after treatment with selective serotonin reuptake inhibitors. However, the major effect was on the tolerability of these drugs rather than efficacy. Results from mirtazapine-treated patients indicate that the effect of this polymorphism on outcome may depend on the mechanism of antidepressant action.

Two randomized, double-blind, placebo-controlled, 6-week studies comparing ziprasidone versus placebo for treatment of bipolar depression (BPD) failed to meet their primary study objectives, indicating that either ziprasidone is ineffective in the treatment of BPD or the study failed. Adult outpatients with bipolar I depression with 17-item Hamilton Rating Scale for Depression total score more than 20 at screening and baseline received either ziprasidone 40 to 80 mg/d, 120 to 160 mg/d, or placebo (study 1), or ziprasidone 40 to 160 mg/d or placebo (study 2). Primary efficacy measure in both studies was change from baseline in Montgomery-Åsberg Depression Rating Scale total scores at week 6 (end of the study). Mixed-model repeated-measures methodology was used to analyze the primary efficacy measure in both studies. Secondary efficacy measures in both studies included Hamilton Rating Scale for Depression total score and Clinical Global Impression-Improvement score. Post hoc analyses were conducted for both studies to examine potential reasons for study failure. In both, ziprasidone treatment groups failed to separate statistically from placebo for change from baseline Montgomery-Åsberg Depression Rating Scale score at week 6. Response rates were 49%, 53%, and 46% for placebo, ziprasidone 40 to 80 mg/d, and ziprasidone 120 to 160 mg/d, respectively (study 1), and 51% and 53% for placebo and ziprasidone 40 to 160 mg/d, respectively (study 2). Ziprasidone 40 to 160 mg/d did not show superiority over placebo at week 6 in the treatment of BPD. Post hoc analyses revealed serious inconsistencies in subject rating that may have limited the ability to detect a difference between drug and placebo response. Rating reliability warrants further investigation to improve clinical trial methodology in psychiatry.

No abstract

Pattern of response to antidepressants has been proposed as a method to identify patients whose improvement is more likely due to drug vs those whose improvement on drug is more likely to be a placebo effect. It is hypothesized that those with 'true-drug initial response pattern' are most likely to benefit from continuation treatment. The relationship between acute patterns of response and subsequent placebo-controlled continuation treatment with the antidepressant mirtazapine is examined. A total of 410 outpatients were treated openly with mirtazapine for 8-12 weeks. Patients who remitted in the acute phase were randomized to continue the same dose of mirtazapine or switched to placebo. Acute phase responders were classified as 'placebo initial response pattern' (early responders and nonpersistent responders) and 'true-drug initial response pattern' (delayed and persistent responders). Of those with a 'true-drug initial response pattern,' 10/40 (25.0%) relapsed with continuation mirtazapine, and 23/41 (56.1%) relapsed when switched to placebo. The difference (31.1%) is significant. Of those with a 'placebo initial response pattern,' 5/36 (13.9%) relapsed with continuation mirtazapine, and 12/39 (30.8%) relapsed with placebo substitution. This difference (16.9%) is not statistically significant. Moreover, the relapse rate for 'true-drug initial response pattern' patients switched to placebo (56.1%) was also significantly greater than for 'placebo initial response pattern' patients switched to placebo (30.8%). It has been suggested that patients with late onset and persistence are more likely to have improved because of drug. This hypothesis gains support from this study because of the different relapse rates of 'true-drug' responders on drug and placebo. The low relapse rate for patients with an acute placebo pattern switched to placebo suggests specific drug effect played a smaller role in their initial improvement.