Comparative efficacy of antidepressants

Do SSRIs differ in their antidepressant efficacy

Selective serotonin reuptake inhibitors (SSRIs) have been extensively studied worldwide and show at least equivalent efficacy to the tricyclic antidepressants (TCAs). Some of the SSRIs have demonstrated superior efficacy to TCAs in a number of subgroups including patients with severe depression, suicidal thoughts or depression associated with anxiety. There is currently a lack of direct comparative data between the different SSRIs, although the few studies which are available indicate overall equal efficacy. However, the pharmacodynamic and pharmacokinetic characteristics may result in different side-effects which might, in turn, lead to a characteristic pattern of use.

Treatment discontinuation with selective serotonin reuptake inhibitors compared with tricyclic antidepressants: a meta-analysis

OBJECTIVE

To assess treatment discontinuation rates with selective serotonin reuptake inhibitors compared with tricyclic antidepressants.

DESIGN

Meta-analysis of 62 randomised controlled trials.

SUBJECTS

6029 patients with major unipolar depression.

MAIN OUTCOME MEASURES

Pooled risk ratios for drop out rates with respect to all cases of discontinuation and those due to side effects and treatment failure.

RESULTS

The total discontinuation rate was 10% lower with selective serotonin reuptake inhibitors than with tricyclic antidepressants (risk ratio 0.90; 95% confidence interval 0.84 to 0.97) and the drop out rate due to side effects was 25% lower (risk ratio 0.75; 0.66 to 0.84). There was no significant difference between drug classes in the drop out rates for treatment failure. The risk ratios for drop out did not differ significantly between individual selective serotonin reuptake inhibitors.

CONCLUSIONS

Selective serotonin reuptake inhibitors are better tolerated than tricyclic antidepressants as measured by total numbers of drop outs. The definite advantage to selective serotonin reuptake inhibitors is explained by fewer drop outs due to side effects. The overall difference, however, is comparatively small and may not be clinically relevant. Analyses of cost effectiveness should not overestimate the advantage to selective serotonin reuptake inhibitors.

Fluency changes in persons who stutter following a double blind trial of clomipramine and desipramine

This study compared fluency changes in adult developmental stuttering speakers treated with two tricyclic antidepressants, clomipramine and desipramine. Clomipramine is primarily a serotonergic reuptake inhibitor, and desipramine, primarily a noradrenergic reuptake inhibitor. Sixteen subjects who stuttered participated in a single-blind placebo, double-blind active drug crossover study lasting 12 weeks. Speech rate and percent fluency did not significantly improve in placebo compared to baseline. Speech rate significantly increased while repeating, reading or constructing sentences, and during a telephone conversation, but no significant changes in percent fluency were found under clomipramine compared to placebo. Speech rate during a telephone conversation and percent fluency while speaking in front of an audience of four to seven listeners significantly increased under clomipramine compared to desipramine. No significant improvements in percent fluency or speech rate were found for any speaking task under desipramine compared to placebo. Twelve of 16 subjects reported improved fluency compared to baseline using clomipramine, whereas 6 reported improvement using desipramine. Because more evidence of improvement was found under clomipramine compared to desipramine, fluency improvement may be related to clomipramine's greater selectivity for serotonergic reuptake inhibition.

Beyond specificity: effects of serotonin and serotonergic treatments on psychobiological dysfunction

Serotonin is a ubiquitous neurotransmitter with widespread projections that provide for the involvement of serotonin in the regulation of many biological and psychological functions. A variety of serotonin receptor subtypes exist that mediate overlapping psychobiological functions and that are targets for a new generation of medications. Although these new generation medications appear to possess great biochemical specificity, their actions extend to many psychiatric disorders, reflecting the many interactions of serotonergic subsystems.

Antidepressant therapy in 138 patients with irritable bowel syndrome: a five-year clinical experience

BACKGROUND

Antidepressant agents may have a therapeutic role in functional gastroenterologic disorders, but controlled investigations in irritable bowel syndrome (IBS) have not provided satisfactory practice recommendations. To help with future study design, we reviewed a five-year clinical experience with antidepressant agents in out-patients with IBS.

METHODS

Presenting features, treatment course, and clinical outcome were determined from a chart review of 138 patients attending a university-based gastroenterology practice.

RESULTS

Patients were treated with up to five antidepressants in separate, consecutive trials if a satisfactory end-point had not been reached. Tricyclic antidepressants were utilized 130 times, newer antidepressants 39 times, and anxiolytic-antidepressants 47 times. Improvement and complete remission in bowel symptoms occurred in 89% and 61% of patients, respectively, during antidepressant therapy. Median dosages being prescribed when remission occurred were less than those conventionally used in clinical psychiatry (50 mg/day for several tricyclic antidepressants). Age, gender, symptom duration, and presence of psychological symptoms did not discriminate those who remitted from those who did not, whereas a pain predominant symptom pattern was more commonly associated with symptom remission (P < 0.05 comparing symptom patterns). Symptom remission was more likely during the first antidepressant treatment than with subsequent trials in the group with continued symptoms (P = 0.01), but nearly half of the patients with side effects or no benefit from the first agent who went on to subsequent trials remitted during treatment with an alternative antidepressant.

CONCLUSIONS

The design of this retrospective review is not capable of determining the efficacy of antidepressants for IBS. Our observations in conjunction with other available data suggest that future trials should employ low daily dosages, carefully assess pain response, include patients with and without active psychiatric symptoms, and utilize a second agent for subjects intolerant or unresponsive to the first.

The efficacy of selective serotonin re-uptake inhibitors in depression: a meta-analysis of studies against tricyclic antidepressants

A meta-analysis of the efficacy of five selective serotonin re-uptake inhibitors (SSRIs) against non-selective and noradrenergic re-uptake inhibitors (mainly tricyclic antidepressants, TCAs) is presented. Fifty five double- blind studies were identified after excluding those multiply reported or with methodological problems likely to bias the outcome in favour of SSRIs. Standardised effect sizes and 95% confidence intervals were calculated based on the difference in the reduction in mean Hamilton depression rating scale (HDRS) scores for the two antidepressants. For studies not reporting standard deviations, the pooled variance from complete studies was used and a variance-weighted mean effect size calculated. There were no differences in efficacy between SSRIs and comparator antidepressants for SSRIs taken together or individually. If studies were classified into high and low depression scores based on a median split of initial HDRS scores, there was a slight advantage to TCAs in the high HDRS group. In addition, SSRIs were slightly less effective than TCAs in in-patients and against combined serotonin and noradrenaline re-uptake inhibitors (clomipramine and amitriptyline). These findings were accounted for by a clinically significant lower efficacy of paroxetine in these subgroups. In contrast, SSRIs as a group were marginally more effective than noradrenergic antidepressants, a finding accounted for by two studies with sertraline. Fluvoxamine was the only SSRI to have been tested adequately in in-patients, where it displayed equal efficacy to TCAs. This meta-analysis confirms that SSRIs and TCAs are in general equally effective, but suggests that paroxetine's efficacy in in-patients and against clomipramine and amitriptyline is not proven.

Plasma concentrations of fluvoxamine and maprotiline in major depression: implications on therapeutic efficacy and side effects

We examined the relationship between plasma concentrations of specific acting antidepressants (fluvoxamine/maprotiline) and clinical improvement as well as the impact of the magnitude of the plasma concentration of these antidepressants on side effects. Patients (32 patients with major depression) were treated within a double-blind parallel trial for four weeks and plasma concentrations were obtained before, on days 8 and 28 of the trial. Although there was a fixed-flexible dosage design it was apparent that 16 patients (89%) of the fluvoxamine group and all patients of the maprotiline group received a dosage between 200 and 300 mg/day in the last week of the trial. Plasma concentrations (mean +/- SD micrograms/l) of fluvoxamine were 125 +/- 91 and 142 +/- 108 on days 8 and 28, respectively and the range of fluvoxamine plasma concentrations on day 28 was from 20 to 417 micrograms/l. Plasma concentrations (mean +/- SD micrograms/l) of maprotiline were 146 +/- 62 and 202 +/- 134 on days 8 and 28, respectively and the range of maprotiline plasma concentration on day 28 was from 12 to 428 micrograms/l. There was no linear relationship between plasma concentrations of both antidepressants (fluvoxamine/maprotiline) and oral dosage. Whereas there was no correlation between fluvoxamine concentration and clinical response there was a tendency that higher maprotiline concentrations were associated with a better antidepressive efficacy at the end of the trial. Higher concentrations of fluvoxamine as well as of maprotiline were significantly (P < 0.05) associated with more side effects.