Do depressed subjects who have failed both fluoxetine and a tricyclic antidepressant respond to the combination?

Lithium Augmentation Versus Citalopram Combination in Imipramine-Resistant Major Depression: A 10-Week Randomized Open-Label Study

PURPOSE/BACKGROUND

According to available international clinical guides, tricyclic antidepressants are our first- or second-line treatment of choice for severe unipolar major depression. However, the therapeutic option after an unsuccessful response to a tricyclic antidepressant drug in unipolar major depression is still unclear.

METHODS/PROCEDURES

This 10-week randomized open-label study assessed the effectiveness of add-on lithium (adjusted to plasma levels) compared with add-on citalopram (30 mg/d) in 104 severe unipolar major depressive patients after a 10-week unsuccessful imipramine (adjusted to plasma level). Efficacy analyses examined changes in the severity of depression symptoms from baseline visit to endpoint and the comparative remission rate between treatment subgroups.

FINDINGS/RESULTS

The randomized sample consisted of 104 imipramine-resistant severe unipolar major depressed patients. Both, the percentage of remitters (40.4% vs 21.1%, P = 0.034) and the mean reduction of the Hamilton Depression Rating Scale score (58.8% vs 42.5%, P = 0.005) were significantly greater in the add-on citalopram subgroup at endpoint visit.

IMPLICATIONS/CONCLUSIONS

Although we should be cautious about generalizing these results to patients with a less severe unipolar major episode, results from the present study suggest that add-on citalopram is a very effective treatment option in unipolar major depressive episodes after an unsuccessful imipramine regimen.

Combining antidepressants: a review of evidence

Sequenced (stepped) treatment approaches are widely endorsed in the management of depression. Combining antidepressants is a recognised step for those failing to respond to monotherapy. Despite the limited evidence base, this strategy is widely used by clinicians in practice. Not every combination used clinically has a sound neuropharmacological rationale and the use of such combinations may increase the side-effect burden without any additional advantage to the patient. Efficacy of various antidepressant combinations along with the data on side-effect profile and toxicity of such combined treatments are reviewed here. The different combinations are considered by each class of antidepressant available in the UK.

Combination pharmacotherapy in unipolar depression

It is estimated that between 60 and 80% of those with major depressive disorder do not achieve full symptomatic remission from first-line antidepressant monotherapy. Residual depressive symptoms substantially impair quality of life and add to the risk of recurrence. It is now clear that depression would benefit from more vigorous treatment, in order to ameliorate its disease burden. While there are established algorithms in situations of treatment resistance, the use of combination pharmacotherapy in unipolar depression is a relatively under-investigated area of treatment and may be an effective and tolerable strategy that maximizes the available resources. This paper reviews the current evidence for combination pharmacotherapy in unipolar depression and discusses its clinical applications.

Targeting Treatment-Resistant Depression

Only 50% of depressed patients achieve remission of symptoms after 2 trials of antidepressants. Therefore one half of patients are considered treatment resistant. Studies have shown that with each failed antidepressant, chances of remission continue to decline. Untreated depressive symptoms lead to impaired social and occupational function, decline of physical health, suicidal thoughts, and increased health care utilization. Clinicians recognize there is an urgent need to find an efficacious treatment, but it becomes more difficult to decide on an appropriate therapy once a patient has failed 2 to 3 trials of antidepressants. An evidence-based review was performed to assess the efficacy and safety of several different antidepressant strategies to help the clinician decide which may be beneficial for specific patients.

Therapeutic options for treatment-resistant depression

Treatment-resistant depression (TRD) presents major challenges for both patients and clinicians. There is no universally accepted definition of TRD, but results from the US National Institute of Mental Health's (NIMH) STAR*D (Sequenced Treatment Alternatives to Relieve Depression) programme indicate that after the failure of two treatment trials, the chances of remission decrease significantly. Several pharmacological and nonpharmacological treatments for TRD may be considered when optimized (adequate dose and duration) therapy has not produced a successful outcome and a patient is classified as resistant to treatment. Nonpharmacological strategies include psychotherapy (often in conjunction with pharmacotherapy), electroconvulsive therapy and vagus nerve stimulation. The US FDA recently approved vagus nerve stimulation as adjunctive therapy (after four prior treatment failures); however, its benefits are seen only after prolonged (up to 1 year) use. Other nonpharmacological options, such as repetitive transcranial stimulation, deep brain stimulation or psychosurgery, remain experimental and are not widely available. Pharmacological treatments of TRD can be grouped in two main categories: 'switching' or 'combining'. In the first, treatment is switched within and between classes of compounds. The benefits of switching include avoidance of polypharmacy, a narrower range of treatment-emergent adverse events and lower costs. An inherent disadvantage of any switching strategy is that partial treatment responses resulting from the initial treatment might be lost by its discontinuation in favour of another medication trial. Monotherapy switches have also been shown to have limited effectiveness in achieving remission. The advantage of combination strategies is the potential to build upon achieved improvements; they are generally recommended if partial response was achieved with the current treatment trial. Various non-antidepressant augmenting agents, such as lithium and thyroid hormones, are well studied, although not commonly used. There is also evidence of efficacy and increasing use of atypical antipsychotics in combination with antidepressants, for example, olanzapine in combination with fluoxetine (OFC) or augmentation with aripiprazole. The disadvantages of a combination strategy include multiple medications, a broader range of treatment-emergent adverse events and higher costs. Several experimental pharmaceutical treatment alternatives for TRD are also being explored in combination with antidepressants or as monotherapy. These less studied alternative compounds include pindolol, inositol, CNS stimulants, hormones, herbal supplements, omega-3 fatty acids, S-adenosyl-L-methionine, folic acid, lamotrigine, modafinil, riluzole and topiramate. In summary, despite an increasing variety of choices for the treatment of TRD, this condition remains universally undefined and represents an area of unmet medical need. There are few known approved pharmacological agents for TRD (aripiprazole and OFC) and overall outcomes remain poor. This might be an indication that depression itself is a heterogeneous condition with a great diversity of pathologies, highlighting the need for careful evaluation of individuals with depressive symptoms who are unresponsive to treatment. Clearly, more research is needed to provide clinicians with better guidance in making those treatment decisions--especially in light of accumulating evidence that the longer patients are unsuccessfully treated, the worse their long-term prognosis tends to be.

Combined antidepressants: clinical experience

OBJECTIVE

To review the current literature on the use of combinations of antidepressive agents.

METHOD

Literature searches were undertaken and reviewed on the use of combinations of antidepressants.

RESULTS

Data sources included surveys, analyses of prescription records, decision algorithms, clinical reports, and studies comparing the monotherapy with combination therapy. More recent surveys recommend combining different selective serotonin reuptake inhibitors (SSRIs), an SSRI plus bupropion or dual action antidepressants plus an SSRI. Decision algorithms recommend an SSRI plus tricyclic antidepressant (TCA) and more recently bupropion plus venlafaxine or mirtazapine. Few controlled clinical trials comparing the combined therapy with monotherapy have been conducted. Beneficial effects have been reported with combinations of TCAs plus mianserin or SSRIs plus mirtazapine.

CONCLUSION

Adding or combining antidepressant medications has advantages for the speed of onset and maintaining the existing response. More rigorous clinical trials comparing combination therapy with monotherapy and for the development of rational treatment guidelines are required.

Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application

Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.

To combine or not to combine? A literature review of antidepressant combination therapy

OBJECTIVE

Treatment resistant depression is a common clinical problem and a major public health concern. The use of antidepressant combinations to overcome treatment resistance, while somewhat controversial, is a popular strategy in practice. This paper reviews published trials on combination antidepressants with a view to inform clinical practice.

METHOD

A systematic but selective review of the published literature was conducted using EMBASE, PSYCHLIT and MEDLINE with relevant search terms.

RESULTS

A number of trials suggesting efficacy of combination antidepressants were found. These are incorporated into a number of treatment guidelines for the management of treatment refractory depression. Clinicians should be cautious regarding pharmacokinetic and pharmacodynamic interactions, including the serotonin syndrome, however combination strategies are an effective option.

CONCLUSIONS

Many antidepressants can be usefully combined especially if they engage separate mechanisms of action. Clinically, antidepressant combinations provide a useful resort in otherwise treatment resistant individuals. However, much further research is needed to determine relative efficacy and determine long term outcome.

Therapeutic alternatives for difficult-to-treat depression: a narrative review of the state of the evidence

Despite the large number of depressed patients who do not respond to first-line antidepressants, the evidence base of alternate strategies is quite thin. In this article, a simple 5-stage system for categorizing treatment-resistant depression (TRD) is described and the evidence pertaining to the major strategies currently utilized is summarized using four grades, ranging from D (case reports only) to A (multiple positive placebo-controlled trials). It is concluded that the level of evidence supporting many of the contemporary strategies used for TRD (eg, combinations of antidepressants and augmentation with medications such as pindolol, buspirone, or modafinil) is scanty at best. Even the fundamental question concerning "to augment or to switch" is not answerable with available data. It is noted that the best-documented treatments (ie, lithium augmentation, switching to a monoamine oxidase inhibitor, and electroconvulsive therapy) are among the least utilized. This state of affairs will improve with completion of the studies of Systematic Treatment Alternatives to Relieve Depression, a large multicenter study of difficult-to-treat depression funded by the National Institute of Mental Health. There is a need for greater collaboration among academicians and organizations, such as the American Psychiatric Association, the National Institute of Mental Health, and the pharmaceutical industry, to ensure that sufficient research is conducted so that clinician's choices for patients with TRD can be guided by empirical evidence.

Double-blind study of high-dose fluoxetine versus lithium or desipramine augmentation of fluoxetine in partial responders and nonresponders to fluoxetine

In a previous study, of 41 depressed patients who had not responded to fluoxetine 20 mg/day, 53% were treated with high-dose fluoxetine (40-60 mg/ day) and responded (i.e., their 17-item Hamilton Rating Scale for Depression [HAM-D-17] score was <7) versus 29% and 25% of patients treated with fluoxetine plus lithium (300-600 mg/day) or fluoxetine plus desipramine (25-50 mg/day), respectively. We wanted to assess whether these findings could be replicated in a larger sample of depressed outpatients. We identified 101 outpatients with major depressive disorder (52 men and 49 women; mean age, 41.6 + 10.6 years) who were either partial responders (n = 49) or nonresponders (n = 52) to 8 weeks of treatment with fluoxetine 20 mg/ day. These patients were randomized to 4 weeks of double-blind treatment with high-dose fluoxetine (40-60 mg/day), fluoxetine plus lithium (300-600 mg/day), or fluoxetine plus desipramine (25-50 mg/day). In the overall group of patients (N = 101), there was no significant difference in response rates across the three treatment groups (high-dose fluoxetine, 42.4%; fluoxetine plus desipramine, 29.4%; fluoxetine plus lithium, 23.5%). Dropout rates were also comparable, ranging from 9.1% (high-dose fluoxetine) to 14.7% (fluoxetine plus desipramine and fluoxetine plus lithium). There were also no significant differences in response rates across the three treatment groups among partial responders (high-dose fluoxetine, 50.0%; fluoxetine plus desipramine, 33.3%; fluoxetine plus lithium, 33.3%) and nonresponders (high-dose fluoxetine, 35.3%; fluoxetine plus desipramine, 26.3%; fluoxetine plus lithium, 12.5%). At the end of the study, the mean lithium level was 0.37 + 0.15 mEq/L (n = 27; range, 0.1-0.8 mEq/L) among lithium-treated patients, and the mean desipramine level was 104.7 + 58.8 ng/mL (n = 22; range, 25-257 ng/mL). There were no significant relationships between lithium or desipramine blood levels and degree of improvement (as measured by the change in HAM-D-17 score). We found no significant differences in efficacy among these three treatment strategies among patients who had failed to respond adequately to 8 weeks of treatment with fluoxetine 20 mg/day, although the high-fluoxetine group was associated with nonsignificantly higher response rates in both partial responders and nonresponders.

Strategies for Treatment Refractory Depression

Ten to thirty percent of patients do not respond adequately to antidepressant therapy. Absolute treatment refractory depression occurs in up to 10% of patients with depression. To date, few studies have addressed this issue. Several treatment options are available for refractory depression, including increasing the dose, extending the treatment period, switching and augmentation strategies, and electroconvulsive therapy. This paper will review some strategies available for treatment refractory depression.

Antidepressant augmentation and combinations

A significant proportion of patients with MDD are treatment resistant or only partial responders to adequate therapy with a single agent. In this situation, one must consider augmentation with another agent. Lithium and thyroid augmentation have been investigated for many years. In a meta-analysis of double-blind studies involving augmentation with lithium or placebo after nonresponse to conventional antidepressants, lithium augmentation was concluded to be the first-line therapy for depressed patients who failed to respond to monotherapy. One important study reported no significant difference in response rates between T3 and lithium as augmentation agents in patients who had failed to respond to TCAs. Very few controlled, double-blind trials show consistently positive results for the other augmentation strategies, although some open-labeled trials and case reports are promising. Additional placebo-controlled, double-blind studies are needed to assess the efficacy and tolerability of all of these agents, especially in combination with the newer classes of antidepressants.

Pharmacotherapy of depression and mixed states in bipolar disorder

The treatment of bipolar depression requires the resolution of depression and the establishment of mood stability. A basic problem is that the treatments used in treating bipolar depression were developed and proven effective for other disease states: antidepressants for unipolar depression, and mood stabilizers for mania. The panel addressed four unresolved questions regarding depression in relation to bipolar disorder: (1) the relative effectiveness of different antidepressant treatments; (2) the relative likelihood of mood destabilization with different antidepressant treatments; (3) the effectiveness and role of mood-stabilizing medicines as antidepressants; and (4) the optimal approach to mixed states. The selection of an antidepressant depends both on its relative lack of mania- or hypomania-provoking potential and on its effectiveness against bipolar depression. There is little definitive evidence distinguishing effectiveness of the major groups of antidepressive agents, so side-effect profiles and pharmacokinetics are major considerations. The underlying bipolar disorder should be treated with mood stabilizers started simultaneously with any antidepressive treatments. Lithium, divalproex sodium and carbamazepine have all been found to be helpful, to some extent, in treating bipolar depressive episodes as well as for long-term mood stabilization. There is little evidence for long-term benefits of antidepressive agents in bipolar disorder, and some evidence that they may destabilize the disorder. Therefore, in contrast to the long-term use of mood-stabilizers, antidepressant use is recommended on a temporary basis. The duration of antidepressant treatment is determined by past history in terms of liability for mood destabilization, and by the ability of the patient to tolerate gradual antidepressant discontinuation without return of depression. Mixed states, where symptoms of depression and mania coexist, are regarded as a predictor of relatively poor response to lithium, and divalproex has been found to be more effective. Carbamazepine may too be useful in mixed states. Most patients with mixed states in actual practice require combinations of mood stabilizers, though there is little controlled data regarding such co-prescription, especially from a long-term perspective.