Comparison between zimeldine and amitriptyline of efficacy and adverse symptoms--a combined analysis of four British clinical trials in depression

A randomized, double-blind, active placebo-controlled study of efficacy, safety, and durability of repeated vs single subanesthetic ketamine for treatment-resistant depression

The strategy of repeated ketamine in open-label and saline-control studies of treatment-resistant depression suggested greater antidepressant response beyond a single ketamine. However, consensus guideline stated the lack of evidence to support frequent ketamine administration. We compared the efficacy and safety of single vs. six repeated ketamine using midazolam as active placebo. Subjects received either six ketamine or five midazolam followed by a single ketamine during 12 days followed by up to 6-month post-treatment period. The primary end point was the change from baseline in the Montgomery-Åsberg Depression Rating Scale (MADRS) score at 24 h after the last infusion. Fifty-four subjects completed all six infusions. For the primary outcome measure, there was no significant difference in change of MADRS scores between six ketamine group and single ketamine group at 24 h post-last infusion. Repeated ketamine showed greater antidepressant efficacy compared to midazolam after five infusions before receiving single ketamine infusion. Remission and response favored the six ketamine after infusion 4 and 5, respectively, compared to midazolam before receiving single ketamine infusion. For those who responded, the median time-to-relapse was nominally but not statistically different (2 and 6 weeks for the single and six ketamine group, respectively). Repeated infusions were relatively well-tolerated. Repeated ketamine showed greater antidepressant efficacy to midazolam after five infusions but fell short of significance when compared to add-on single ketamine to midazolam at the end of 2 weeks. Increasing knowledge on the mechanism of ketamine should drive future studies on the optimal balance of dosing ketamine for maximum antidepressant efficacy with minimum exposure.

Comparing the onset of action of antidepressants: Comparison of different criteria applied to the same data set

The issue of early onset of action (EOA) of an antidepressant was addressed by several authors. Unfortunately so far there is neither consensus nor convention on the definitions of EOA, or on measures and methods of assessments. There are several quite different approaches to the statistical analysis of the data. Our objective was to compare the results concerning EOA obtained by different statistical techniques applied on a data set which was generated by several independent conclusive double-blind, placebo controlled randomised trials with two antidepressants. The following statistical techniques were used: 1) statistically significant difference for the first time; 2) statistically significant and clinically relevant difference for the first time; 3) pattern analysis; 4) classical survival analysis without 'sustained response'; 5) survival analysis with sustained response. The advantages and drawbacks of different methods are discussed.

Atypical depression, somatic depression and anxious depression in women: are they gender-preferred phenotypes?

BACKGROUND

Both depression and anxiety disorders affect women at rates significantly greater than men. Women also have a documented higher frequency of comorbid depression and anxiety disorders, and a three-fold higher prevalence of atypical depression.

HYPOTHESES

These gender differences are mainly due to specific depressive phenotypes including anxious depression and atypical depression. The prevalence of comorbid anxiety and depression strongly suggests overlap of pathophysiological mechanisms-which in women are also affected by fluctuations in gonadal hormones. Similar efficacy of serotonergic antidepressants as treatment for anxiety disorders as well as depressions further underscores the blurred boundaries between these two descriptive entities.

CONCLUSIONS

Symptoms of depression and anxiety may be a departure point for differential diagnosis in which dimensionally-based phenotypes substantiated by pathobiology would replace current descriptive entities. It is suggested that at least some biologically-based dysphorias may be specific to women, ensuing from the combination of specific vulnerabilities, and complex interactions between brain mechanisms and gonadal hormones.

Assessing activity onset time and efficacy for clinically effective antidepressant and antimanic drugs in animal models based on dominant-submissive relationships

There is confusion in the literature on the measurement of the drug activity onset time (AOT) for both clinical and non-clinical studies of antidepressant and antimanic drugs. The questions asked are: How often and at which time points should drug effects be measured? At what level of a drug effect should AOT be determined? Is the placebo (control) effect important for consideration of drug AOT? This paper reviews approaches taken to answer these questions and to assess drug therapeutic AOT. The first part of the paper is devoted to a review of methods used in clinical trials with depression as an indication. The second part is focused on approaches taken in animal models of depression and how they could help in assessing drug AOT. Finally, a summary of pharmacological values on which the AOT depends is presented and a new statistical approach to data analysis method proposed. The allied experimental design for pre-clinical and clinical studies may help to characterize and differentiate AOT for available and new generation of antidepressants and antimanic drugs.

Onset of action for duloxetine 60 mg once daily: double-blind, placebo-controlled studies

BACKGROUND

It is widely believed that most antidepressant medications exhibit a delay of 2-4 weeks before clinically relevant improvement can be observed among patients. During this latency period, patients continue to be symptomatic and functionally impaired. Thus, time to onset of effect is an important attribute of a new pharmacotherapy. We assessed the onset of effect for duloxetine, utilizing analytical methods previously recommended in the literature.

METHOD

Efficacy data were pooled from two identical, but independent, randomized, double-blind, placebo-controlled, 9-week clinical trials of duloxetine (60 mg QD). Efficacy measures included the 17-item Hamilton Rating Scale for Depression (HAMD(17)), HAMD(17) subscales (Maier, core, and anxiety), and the Clinical Global Impression of Severity (CGI-S) and Patient Global Impression of Improvement (PGI-I) scales. In each individual study, duloxetine demonstrated statistically significant advantages over placebo on multiple outcomes. The present analysis utilized pooled data to more accurately and fully characterize the onset of effect for duloxetine.

RESULTS

Median times to sustained improvements of 10% and 20% in the HAMD(17) total score among duloxetine-treated patients were 14 days and 21 days, respectively, compared with 34 days and 49 days, respectively, for placebo-treated patients (p < 0.001 for both results). The median time to sustained 30% improvement in HAMD(17) total score was 35 days for duloxetine-treated patients, while the median time for placebo-treated patients was not estimable since less than half of the patients met this criterion by the end of the trial. For duloxetine-treated patients, median times to sustained 10%, 20%, and 30% improvements on the Maier subscale of the HAMD(17) were the same as those for the HAMD(17) total score: 14, 21, and 35 days, respectively. However, in other analyses, changes in core emotional symptoms as measured by subscales of the HAMD(17) were somewhat faster than changes in overall symptomatology. The probabilities of achieving a sustained 30% improvement (Maier subscale) at Week 1 for duloxetine- and placebo-treated patients were 16.2% vs. 4.8%, respectively (p < 0.001). The corresponding probabilities of sustained improvement at Weeks 2 and 3 for duloxetine were 32.5% and 45.4%, respectively, compared to 12.8% and 21.4% for placebo ((p < 0.001 for both comparisons).

CONCLUSION

The absence of an active comparator limits the conclusions which can be drawn regarding the rapidity of onset of clinically meaningful improvement. However, results from the present investigation may be useful to clinicians in consideration of treatment options for individual patients.

The pharmacology of putative early-onset antidepressant strategies

Depression is a serious and burdensome illness. Although selective serotonin reuptake inhibitors (SSRIs) have improved safety and tolerability of antidepressant treatment efficacy, the delay in the onset of action have not been improved. There is evidence to suggest that the delay in onset of therapeutic activity is a function of the drugs, rather than the disease. This suggests that research into the biological characteristics of depression and its treatments may yield faster-acting antidepressants. Emerging evidence from clinical studies with mirtazapine, venlafaxine and SSRI augmentation with pindolol suggests that these treatments may relieve antidepressant symptoms more rapidly than SSRIs. The putative mechanism of action of faster-acting antidepressant strategies presented here purports that conventional antidepressants acutely increase the availability of serotonin (5-hydroxytryptamine, 5-HT) or noradrenaline (NA), preferentially at their cell body level, which triggers negative feedback mechanisms. After continued stimulation, these feedback mechanisms become desensitised and the enhanced 5-HT availability is able to enhance 5-HT and/or NA neurotransmission. Putative fast-onset antidepressants, on the other hand, may uncouple such feedback control mechanisms and enhance 5-HT and/or NA neurotransmission more rapidly. Further studies are required to characterise in detail the interactions between NA and 5-HT systems and to definitively establish the early onset of candidate antidepressants such as mirtazapine, venlafaxine and pindolol augmentation.

Onset of action of antidepressants: results of different analyses

Because the value of antidepressants is hampered by their delay in onset of action, considerable attention has been focused on developing a drug that acts more rapidly. However, although specific studies are now ongoing, there have been no peer-reviewed prospective onset of action trials published in the literature to date. Some data are currently available from post-hoc pooled analyses and numerous methods have been developed for evaluating the onset of action; these include the time to response, the time to onset of therapeutic effect, pattern analysis and survival analyses. Such an analysis of four large-scale, double-blind studies has provided evidence for an earlier onset of action with mirtazapine than with the SSRIs (fluoxetine, paroxetine and citalopram). Significant differences were seen between mirtazapine and the SSRIs after 1 week of treatment. This effect was consistent across the four different methodologies and appears to be due to a specific antidepressant effect rather than an early effect on, for example, sleep. These findings await confirmation from specifically designed prospective onset of action studies.

Baseline characteristics of major depressive disorder patients in clinical trials in Europe and United States: is there a transatlantic difference?

There is a widely spread belief that different patients are being recruited into antidepressant clinical trials conducted in Europe and the USA which is probably generated by the fact that recruitment strategies vary between the two continents. In order to get an insight into the patients' characteristics in clinical studies on both continents, we compared the baseline characteristics of depressed patients in a database of a cancelled development program of an antidepressant (2220 patients, Intention-to-Treat group). For the evaluation of continental differences, we compared the elements of demographics, previous psychiatric history, DSM-III-R criteria, HAM-D and MADRS total scores and separate items and/or factors and CGI severity scores at baseline. USA patients had statistically significantly higher baseline values on height, weight and BMI. European patients showed statistically significantly higher baseline severity scores on HAM-D, MADRS and CGI. Furthermore, European patients had statistically significantly higher baseline scores on HAM-D factors I ('anxiety/somatization'), VI ('sleep disturbance'), and HAM-D Angst anxiety/agitation factor, whereas USA patients had a statistically significantly higher baseline value on the Bech depression factor and the HAM-D Angst retarded depression factor. European patients appear to have a more severe depressive episode with more anxiety and melancholic features. Some of the statistically significant differences found may be the result of a large sample size and are probably without any clinical relevance when the absolute size of the difference is taken into account. Our opinion is that the differences found in our sample between European and USA populations are much smaller than is generally expected and not of a magnitude that would question the reliability of the results obtained in our global world-wide, antidepressant drug development program. If our findings were reproducible in other antidepressant databases it would indicate that data gathered in Europe and the USA within a global antidepressant drug development can be pooled.

A Canadian multicenter, double-blind study of paroxetine and fluoxetine in major depressive disorder

BACKGROUND

Recent studies have suggested clinical differences among selective serotonin reuptake inhibitors. In a 12-week randomized, multicenter, double-blind trial, the antidepressant and anxiolytic efficacy of the selective serotonin reuptake inhibitors paroxetine and fluoxetine was compared in patients with moderate to severe depression.

METHODS

A total of 203 patients were randomized to fixed doses (20 mg/day) of paroxetine or fluoxetine for the first six weeks of therapy. From week 7-12, dosing could be adjusted biweekly, as required (paroxetine 20-50 mg/day, and fluoxetine 20-80 mg/day). The mean prescribed doses were paroxetine 25.5 mg/day (range 20.0-40.2 mg/day), and fluoxetine 27.5 mg/day (range 20.0-59.5 mg/day). Emergence of motor nervousness or restlessness was assessed using the ESRS scale for akathisia.

RESULTS

Both active treatments demonstrated comparable antidepressant efficacy (HAM-D, CGI). Anxiolytic activity of the two drugs (COVI, STAI, HAM-D) was also comparable. However, paroxetine was found to be superior to fluoxetine on two subscore measures at week 1 of therapy (HAM-D Agitation item, p < 0.05; Psychic Anxiety item, p < 0.05), with no differences detected after week 2. The overall incidence of adverse effects was comparable in the two treatment groups. Constipation, dyspepsia, tremor, sweating and abnormal ejaculation were more common in paroxetine-treated subjects, whereas nausea and nervousness were more frequent in fluoxetine-treated patients. Weight loss was more common in the fluoxetine versus paroxetine group (11.88% versus 2.94%, respectively). ESRS scores for akathisia were low throughout the study and showed little change.

LIMITATIONS

Differences observed between the two drugs in antianxiety effects were limited to two measures of anxiety among several others.

DISCUSSION

The data indicate that paroxetine and fluoxetine have comparable antidepressant and anxiolytic efficacy. Paroxetine appears to produce an earlier improvement in agitation and psychic anxiety symptoms compared with fluoxetine.

A randomized, double-blind comparison of a rapidly escalating dose of venlafaxine and imipramine in inpatients with major depression and melancholia

A double-blind, randomized, parallel study in 167 hospitalized patients with major depression and melancholia was conducted to determine if rapidly escalated doses of venlafaxine produced an earlier response, compared with rapidly escalated doses of imipramine. The daily dose of venlafaxine was rapidly increased to 375 mg/day over a five-day period, was maintained at this level for 10 days, and then was reduced to 150 mg/day for the remainder of the study. The imipramine dose was rapidly increased to 200 mg/day over five days and was maintained at this level to the end of the study. The primary efficacy variables were time to response and time to sustained response on the HAM-D and MADRS. No differences in the response rates on the HAM-D or MADRS were observed between treatments. However, among patients who demonstrated a response on the HAM-D, there was a significantly faster onset of response (p = 0.036) and sustained response (p = 0.018) in the venlafaxine group. The median time to response on the HAM-D among responders was 14 days with venlafaxine and 21 days with imipramine. However, no differences between treatments were observed among responders on the MADRS (median time to response: 15 days for venlafaxine, 18 days for imipramine). Study events were reported in 69% of venlafaxine-treated patients and 76% of imipramine-treated patients. In severely depressed patients with melancholia, a faster onset of response was observed with venlafaxine on the HAM-D, but not the MADRS, and maximal tolerated doses of venlafaxine and imipramine were comparable for overall efficacy. These results confirm and extend previous observations and suggest that venlafaxine may have an early onset of action and may produce a rapid response in hospitalized patients with severe depression complicated by melancholia.

Effect of monoamine reuptake inhibiting antidepressants on major histocompatibility complex expression on macrophages in normal rats and rats with experimental allergic neuritis (EAN)

This study examined the modulation of IFN-gamma induced MHC class I and II expression on normal Lewis rats and rats with EAN peritoneal macrophages cultured in the absence or presence of 10(-4)-10(-8) M of the 5-HT reuptake inhibiting antidepressants zimeldine, and its metabolites norzimeldine and cpp200 oxalate as well as the antidepressants clomipramine and imipramine, in addition amitriptyline, nortriptyline and maprotiline in EAN rats. In normal rats, MHC class I expression was suppressed by the antidepressants zimeldine, norzimeldine and cpp200 oxalate at concentrations up to 10(-5) M. At concentrations between 10(-6) to 10(-8) M, the same drugs significantly enhanced MHC class expression. Clomipramine at 10(-8) M and imipramine at 10(-6)-10(-7) M enhanced MHC class I expression, while the MHC class II expression was not significantly influenced by concentrations < or = 10(-5) M of these two drugs. In EAN rats, MHC class I expression was enhanced by zimeldine, cpp200, imipramine, and nortriptyline at 10(-5)-10(-8) M, amitriptyline at 10(-5)-10(-7) M as well as by norzimeldine and clomipramine at 10(-6) M-10(-8) M. However, maprotiline at 10(-4)-10(-6) M suppressed class I expression in the presence of 0.5 U/ml and 1.0 U/ml of IFN-gamma. MHC class II expression was suppressed by cpp200 and clomipramine at 10(-4)-10(-5) M in presence of 0.5 U/ml of IFN-gamma. At concentrations < 10(-5) M most tested drugs significantly enhanced IFN-gamma induced MHC class II expression. Compared to the results in normal rats, drug effects on EAN macrophages were more pronounced and reached higher levels of significance. The 5-HT reuptake inhibiting antidepressants also exerted a modulatory effect on MHC class I and II in EAN rat macrophages even in the absence of IFN-gamma. The modulatory effect of antidepressant drugs on IFN-gamma induced MHC class I and II expression may contribute to their influence on demyelinating autoimmune diseases, and may have implications for their clinical use.

Effects of zimeldine and its metabolites, clomipramine, imipramine and maprotiline in experimental allergic neuritis in Lewis rats

The influence of the selective serotonin (5-HT) reuptake inhibiting antidepressant zimeldine and its metabolite norzimeldine was tested on experimental allergic neuritis (EAN) in Lewis rats, which is an animal model of the Guillain-Barré syndrome (GBS) in man. Zimeldine and norzimeldine both suppressed clinical signs of actively induced EAN when given at a dose of 20 mg/kg/day intraperitoneally via osmotic pumps. The effects of zimeldine, its metabolites norzimeldine and CPP 200 as well as of the antidepressants clomipramine, imipramine and maprotiline on in vitro immune response were tested. Thereby we used an immunospot assay for interferon-gamma (IFN-gamma) produced by lymph node mononuclear cells (MNC), which reflects number of memory T lymphocytes activated by antigen or lectin, in this experiment bovine peripheral nerve myelin (BPM) and phytohemagglutinin (PHA), respectively. In the IFN-gamma secretion assay zimeldine, CPP 200, clomipramine and maprotiline all in a concentration-dependent mode reduced the number of IFN-gamma secreting cells while norzimeldine and imipramine did not affect the IFN-gamma secretion. In assays for proliferation in response to antigen or lectin, the concentration 10(-4) M was judged toxic for all substances tested, and at concentrations below that all but zimeldine showed a dose-dependent slight reduction of MNC proliferation. The action of several drugs on induced T cell secretion of IFN-gamma suggests that the mechanisms for the suppressive effect of zimeldine and norzimeldine on EAN symptoms can be due to an action on myelin T cell autoreactivity. All the monoamine reuptake inhibiting antidepressants tested in this study showed immunomodulatory effects by either a reduction of the number of IFN-gamma-secreting cells or the MNC proliferation. These observations call for further studies of immunological mechanisms in the pathogenesis of mental disorders as well as on the potential role of drugs acting on the monoamine systems in the treatment of recognized autoimmune diseases.

No crossover reactions to citalopram or paroxetine among patients hypersensitive to zimeldine

Five patients who reacted with the hypersensitive syndrome to zimeldine showed no reaction to one of two other selective 5-HT reuptake inhibitors, citalopram or paroxetine. This further strengthens the impression that the mechanism for the hypersensitivity syndrome induced by zimeldine does not seem to be related primarily to the 5-HT reuptake inhibition as such.

Identification of meta-analyses. The need for standard terminology

Our efforts to identify published articles describing meta-analyses of clinical trials illustrate the need for standard terminology to facilitate retrieval. We found 119 articles describing meta-analyses and eligible for inclusion in MEDLINE, and yet when we searched MEDLINE, using strategies based on textwords and medical subject headings (MeSH), only 48% of the 119 articles were identified. Sixty-eight (57%) of the 119 articles contained at least one of the terms "meta-analysis," "pooling," or "overview" in the title or abstract. The importance of meta-analyses in the evaluation of medical treatments argues for more disciplined use of a specific term in order to facilitate identification of articles. The fact that the National Library of Medicine has started in 1989 to index articles describing meta-analyses using the MeSH META-ANALYSIS underscores this argument.

New antidepressants and 5-HT uptake inhibitors

The efficacy of 5-HT uptake inhibitors, including paroxetine, as antidepressants is compared with that of the reference tricyclic antidepressants. It is suggested that some of the older tricyclic antidepressants might not have been released for general clinical use if tested by today's rigorous standards. Placebo-controlled, multicentre studies indicate that 5-HT uptake inhibitors are both effective as antidepressants and well tolerated by depressed patients. They also appear to have a role in the treatment of depression when associated with personality disorders, in the treatment of obsessive-compulsive disorder and bulimia, and in resistant depression. Moreover, the evidence for efficacy in the prophylaxis of depression is better established for 5-HT uptake inhibitors than for reference antidepressants.

Anxiety as part of depression

Changes in diagnostic criteria have shown a trend towards a broader definition of depression. Thus, a number of patients who would previously have been considered to be suffering from anxiety states are now classified as having major depressive illness according to the criteria of the Diagnostic Statistical Manual III. Despite this, such patients show a good response to antidepressant drugs (compared to placebo) if their severity of depression is above 15 on the Hamilton depression scale. It therefore seems likely that there is a common biological substrate underlying both anxiety states and depressive illness, but this issue remains somewhat controversial. The suggestion that the 5-HT system is involved in the mediation of anxiety is considered. Further evidence is required before definite conclusions can be drawn, but it seems clear that anxiolytic activity is not dependent on sedative properties.