Combination treatment with noradrenalin and serotonin reuptake inhibitors in resistant depression

The potential for adverse effects in fish exposed to antidepressants in the aquatic environment

Antidepressants are one of the most commonly prescribed pharmaceutical classes for the treatment of psychiatric conditions. They act via modulation of brain monoaminergic signaling systems (predominantly serotonergic, adrenergic, dopaminergic) that show a high degree of structural conservation across diverse animal phyla. A reasonable assumption, therefore, is that exposed fish and other aquatic wildlife may be affected by antidepressants released into the natural environment. Indeed, there are substantial data reported for exposure effects in fish, albeit most are reported for exposure concentrations exceeding those occurring in natural environments. From a critical analysis of the available evidence for effects in fish, risk quotients (RQs) were derived from laboratory-based studies for a selection of antidepressants most commonly detected in the aquatic environment. We conclude that the likelihood for effects in fish on standard measured end points used in risk assessment (i.e., excluding effects on behavior) is low for levels of exposure occurring in the natural environment. Nevertheless, some effects on behavior have been reported for environmentally relevant exposures, and antidepressants can bioaccumulate in fish tissues. Limitations in the datasets used to calculate RQs revealed important gaps in which future research should be directed to more accurately assess the risks posed by antidepressants to fish. Developing greater certainty surrounding risk of antidepressants to fish requires more attention directed toward effects on behaviors relating to individual fitness, the employment of environmentally realistic exposure levels, on chronic exposure scenarios, and on mixtures analyses, especially given the wide range of similarly acting compounds released into the environment.

Role of central serotonin and noradrenaline interactions in the antidepressants' action: Electrophysiological and neurochemical evidence

The development of antidepressant drugs, in the last 6 decades, has been associated with theories based on a deficiency of serotonin (5-HT) and/or noradrenaline (NA) systems. Although the pathophysiology of major depression (MD) is not fully understood, numerous investigations have suggested that treatments with various classes of antidepressant drugs may lead to an enhanced 5-HT and/or adapted NA neurotransmissions. In this review, particular morpho-physiological aspects of these systems are first considered. Second, principal features of central 5-HT/NA interactions are examined. In this regard, the effects of the acute and sustained antidepressant administrations on these systems are discussed. Finally, future directions including novel therapeutic strategies are proposed.

Dual Antidepressant Duloxetine Blocks Nicotinic Receptor Currents, Calcium Signals and Exocytosis in Chromaffin Cells Stimulated with Acetylcholine

The inhibition of nicotinic acetylcholine receptors (nAChRs) has been proposed as a potential strategy to develop new antidepressant drugs. This is based on the observation that antidepressants that selectively block noradrenaline (NA) or serotonin (5-HT) reuptake also inhibit nAChRs. Dual antidepressants blocking both NA and 5-HT reuptake were proposed to shorten the delay in exerting their clinical effects; whether duloxetine, a prototype of dual antidepressants, also blocks nAChRs is unknown. Here we explored this question in bovine chromaffin cells (BCCs) that express native α₃, α₅, and α₇ nAChRs and in cell lines expressing human α₇, α₃β₄, or α₄β₂ nAChRs. We have found that duloxetine fully blocked the acetylcholine (ACh)-elicited nicotinic currents in BCCs with an IC₅₀ of 0.86 µM. Such blockade seemed to be noncompetitive, voltage dependent, and partially use dependent. The ACh-elicited membrane depolarization, the elevation of cytosolic calcium ([Ca²⁺]_c), and catecholamine release in BCCs were also blocked by duloxetine. This blockade developed slowly, and the recovery of secretion was also slow and gradual. Duloxetine did not affect Na⁺ or Ca²⁺ channel currents neither the high-K⁺-elicited [Ca²⁺]_c transients and secretion. Of interest was that in cell lines expressing human α₇, α₃β₄, and α₄β₂ nAChRs, duloxetine blocked nicotinic currents with IC₅₀ values of 0.1, 0.56, and 0.85 µM, respectively. Thus, in blocking α₇ receptors, which are abundantly expressed in the brain, duloxetine exhibited approximately 10-fold to 100- fold higher potency with respect to reported IC₅₀ values for various antidepressant drugs. This may contribute to the antidepressant effect of duloxetine.

Pharmacological management of treatment-resistant depression

The management of patients with depression who have failed to respond to antidepressant medication is a common problem in general and old age psychiatry. It has been estimated that about 20–30% of patients with major depression fail to respond to treatment with a single antidepressant drug given in adequate dosage for an appropriate period of time. At the current time there are many possible ways to pursue pharmacological treatment, but few controlled trials to help us choose between the various options. In addition there are few clinical predictors to help match patients to an appropriate treatment.

Prescribing psychotropic drugs for the elderly

The pharmacological treatment of the elderly differs from that of younger patients, mainly because of altered pharmacokinetics and the higher proportion of patients with organic disorders. We deal here with dementia, delirium, affective disorder, late-life schizophrenia, sleep disturbance, and rapid tranquillisation.

Anti-depressant and anxiolytic potential of Acacia hydaspica R. Parker aerial parts extract: Modulation of brain antioxidant enzyme status

BACKGROUND

Oxidative stress may link to psychiatric disorders, and is being regarded as a plausible mechanism that can affect the regulation of these illnesses. The present study was undertaken to investigate the antidepressant and anxiolytic potential of A. hydaspica R. parkers. Brain oxidative stress enzyme levels were analyzed to correlate depression and stress with brain antioxidant status.

METHODS

Antidepressant and anxiolytic effect of methanol extract of A. hydaspica and its derived soluble fractions [n-hexane (AHH), ethyl-acetate (AHE), chloroform (AHC), n-butanol (AHB) and remaining aqueous fraction (AHA)] was investigated by using three behavioral models; the Forced swimming test, Tail suspension test and Elevated plus-maze test (EPM). Chronic unpredictable mild stress (CMS) was employed to induce stress in rats. AHM and AHE (200 mg/kg, p.o), fluoxetine (5 mg/kg, i.p) and diazepam (DZM) (1 mg/kg, p.o) were administered during the 7 day stress exposure period, and rats were assessed for antidepressant and anxiolytic behavioral despair paradigms. Antioxidant enzymes and oxidative stress markers were measured in brain tissue of depressed rats. Phytochemical analysis was done by GCMS experimentation.

RESULTS

AHM and AHE (acute dose) significantly (p < 0.0001) reduced the immobility time and ameliorated climbing behavior as compared to the control in FST and TST, and similar to fluoxetine. AHM and AHE showed significant (p < 0.0001) anxiolytic potential in EPM, and comparable to DZM (1 mg/kg b.w., i.p). Significant decrease in antioxidant enzyme levels and increase in MDA, H2O2 and NO level were observed in stressed rats. AHM and AHE (for 7 days/CMS) significantly improved behavior in FST, TST and EPMT. Treatment also improved antioxidant enzyme level and controlled the oxidative stress markers in brain tissues. GCMS analysis indicated the presence of 10 different chemical constituents in A. hydaspica.

CONCLUSION

The present study revealed that A. hydaspica exerts an antidepressant and anxiolytic effect by improving brain antioxidant status. The observed activities might be due to the presence of diverse phytochemicals.

Is increased antidepressant exposure a contributory factor to the obesity pandemic?

Major depressive disorder (MDD) and obesity are both common heterogeneous disorders with complex aetiology, with a major impact on public health. Antidepressant prescribing has risen nearly 400% since 1988, according to data from the Centers for Disease Control and Prevention (CDC). In parallel, adult obesity rates have doubled since 1980, from 15 to 30 percent, while childhood obesity rates have more than tripled. Rising obesity rates have significant health consequences, contributing to increased rates of more than thirty serious diseases. Despite the concomitant rise of antidepressant use and of the obesity rates in Western societies, the association between the two, as well as the mechanisms underlying antidepressant-induced weight gain, remain under explored. In this review, we highlight the complex relationship between antidepressant use, MDD and weight gain. Clinical findings have suggested that obesity may increase the risk of developing MDD, and vice versa. Hypothalamic-pituitary-adrenal (HPA) axis activation occurs in the state of stress; concurrently, the HPA axis is also dysregulated in obesity and metabolic syndrome, making it the most well-understood shared common pathophysiological pathway with MDD. Numerous studies have investigated the effects of different classes of antidepressants on body weight. Previous clinical studies suggest that the tricyclics amitriptyline, nortriptyline and imipramine, and the serotonin norepinephrine reuptake inhibitor mirtazapine are associated with weight gain. Despite the fact that selective serotonin reuptake inhibitor (SSRI) use has been associated with weight loss during acute treatment, a number of studies have shown that SSRIs may be associated with long-term risk of weight gain; however, because of high variability and multiple confounds in clinical studies, the long-term effect of SSRI treatment and SSRI exposure on body weight remains unclear. A recently developed animal paradigm shows that the combination of stress and antidepressants followed by long-term high-fat diet results, long after discontinuation of antidepressant treatment, in markedly increased weight, in excess of what is caused by high-fat diet alone. On the basis of existing epidemiological, clinical and preclinical data, we have generated the testable hypothesis that escalating use of antidepressants, resulting in high rates of antidepressant exposure, might be a contributory factor to the obesity epidemic.

[Sequential prescriptions: Arguments for a change of therapeutic patterns in treatment resistant depressions]

Among the therapeutic strategies in treatment of resistant depression, the use of sequential prescriptions is discussed here. A number of observations, initially quite isolated and few controlled studies, some large-scale, have been reported, which showed a definite therapeutic effect of certain requirements in sequential treatment of depression. The Sequenced Treatment Alternatives to Relieve Depression Study (STAR*D) is up to now the largest clinical trial exploring treatment strategies in non psychotic resistant depression in real-life conditions with an algorithm of sequential decision. The main conclusions of this study are the following: after two unsuccessful attempts, the chance of remission decreases considerably. A 12-months follow-up showed that the higher the use of the processing steps were high, the more common the relapses were during this period. The pharmacological differences between psychotropic did not cause clinically significant difference. The positive effect of lithium in combination with antidepressants has been known since the work of De Montigny. Antidepressants allow readjustment of physiological sequence involving different monoaminergic systems together. Studies with tricyclic antidepressant-thyroid hormone T3: in depression, decreased norepinephrine at the synaptic receptors believed to cause hypersensitivity of these receptors. Thyroid hormones modulate the activity of adrenergic receptors. There would be a balance of activity between alpha and beta-adrenergic receptors, depending on the bioavailability of thyroid hormones. ECT may in some cases promote pharmacological response in case of previous resistance, or be effective in preventing relapse. Cognitive therapy and antidepressant medications likely have an effect on different types of depression. We can consider the interest of cognitive therapy in a sequential pattern after effective treatment with an antidepressant effect for treatment of residual symptoms, preventing relapses and recurrences, in antidepressant maintenance. These data support the interest of therapeutic strategies based on evolutionary criteria. Sequential models inspired by statistical methods may incorporate the effects of a future treatment by measuring the current one.

Antidepressant drug development: Focus on triple monoamine reuptake inhibition

Many patients with major depressive disorder (MDD) only partially respond, and some have no clinically meaningful response, to current widely used antidepressant drugs. Due to the purported role of dopamine in the pathophysiology of depression, triple-reuptake inhibitors (TRIs) that simultaneously inhibit serotonin (5-HT), norepinephrine (NE) and dopamine reuptake could be a useful addition to the armamentarium of treatments for MDD. A TRI should more effectively activate mesolimbic dopamine-related reward-networks, restore positive mood and reduce potent 5-HT reuptake blockade associated "hypodopaminergic" adverse effects of decreased libido, weight gain and "blunting" of emotions. On the other hand, dopaminergic effects raise concern over abuse liability and TRIs may have many of the cardiovascular effects associated with NET inhibition. Several clinical development programs for potential TRI antidepressants have failed to demonstrate significantly greater efficacy than placebo or standard of care. Successful late-stage clinical development of a TRI is more likely if experimental research studies in the target population of depressed patients have demonstrated target engagement that differentially and dose-dependently improves assessments of reward-network dysfunction relative to existing antidepressants. TRI treatment could be individualized on the basis of predictive markers such as the burden of decreased positive mood symptoms and/or neuroimaging evidence of reward network dysfunction. This review focuses on how the next generation of monoamine-based treatments could be efficiently developed to address unmet medical need in MDD.

A randomized double-blind, placebo-controlled trial of venlafaxine-extended release for co-occurring cannabis dependence and depressive disorders

AIM

To evaluate whether venlafaxine-extended release (VEN-XR) is an effective treatment for cannabis dependence with concurrent depressive disorders.

DESIGN

This was a randomized, 12-week, double-blind, placebo-controlled trial of out-patients (n = 103) with DSM-IV cannabis dependence and major depressive disorder or dysthymia. Participants received up to 375 mg VEN-XR on a fixed-flexible schedule or placebo. All patients received weekly individual cognitive-behavioral psychotherapy that primarily targeted marijuana use.

SETTINGS

The trial was conducted at two university research centers in the United States.

PARTICIPANTS

One hundred and three cannabis-dependent adults participated in the trial.

MEASUREMENTS

The primary outcome measures were (i) abstinence from marijuana defined as at least two consecutive urine-confirmed abstinent weeks and (ii) improvement in depressive symptoms based on the Hamilton Depression Rating Scale.

FINDINGS

The proportion of patients achieving a clinically significant mood improvement (50% decrease in Hamilton Depression score from baseline) was high and did not differ between groups receiving VEN-XR (63%) and placebo (69%) (χ1 (2)  = 0.48, P = 0.49). The proportion of patients achieving abstinence was low overall, but was significantly worse on VEN-XR (11.8%) compared to placebo (36.5%) (χ1 (2)  = 7.46, P < 0.01; odds ratio = 4.51, 95% confidence interval: 1.53, 13.3). Mood improvement was associated with reduction in marijuana use in the placebo group (F1,179  = 30.49, P < 0.01), but not the VEN-XR group (F1,186  = 0.02, P = 0.89).

CONCLUSIONS

For depressed, cannabis-dependent patients, venlafaxine-extended release does not appear to be effective at reducing depression and may lead to an increase in cannabis use.

The strategy of combining antidepressants in the treatment of major depression: clinical experience in spanish outpatients

Introduction. The combination of antidepressants is a useful tool in the treatment of major depression, especially in cases where there is a partial response to antidepressant monotherapy. However, the use of this strategy is a matter of controversy, and its frequency of use in clinical practice is not clear. The aim of our study is to assess the use of antidepressants combination in Spain by reviewing three databases used between 1997 and 2001. Methods. Databases pertain to patients who are study subjects of major depression treatment. These databases are a result of studies performed in Spain and in which 550 psychiatrists participated. The total studied sample was comprised of N = 2, 842 patients, aged over 18, fitting DSM-IV criteria for Major Depressive Episode. The percentage of patients who received more than one antidepressant and the types of combinations used was described. Subsequently, a comparative study between the group which received a combination of antidepressants (N = 64) and the group which received antidepressant monotherapy (N = 775) was performed. Results. 27.1% of patients were on antidepressive monotherapy treatment, and 2.2% were on combination therapy. In the comparison of patients on combination therapy and monotherapy, there were significant differences only in episode duration (P = 0.001). The most frequent combinations are SSRIs and tricyclic antidepressants. The active principle most widely combined is fluoxetine. Conclusions. The prevalence of use of antidepressant combination therapy is 2.2% of the global sample and 8.3% of treated patients. Other than duration of the depressive episode, no clinical characteristics exclusive to patients who received combination rather than monotherapy were found. Our study found that the most frequent combination is SSRIs + TCAs, also being the most studied.

Pharmacological and clinical profile of newer antidepressants: implications for the treatment of elderly patients

The pharmacological treatment of older adults with major depressive disorder presents a variety of challenges, including a relative lack of high quality studies designed to measure the efficacy and safety of antidepressants specific to this patient population. Gaining a clear understanding of how to use antidepressants in elderly patients with depression, especially new and widely used agents, would provide valuable insight to clinicians. The purpose of the current article is to review the pharmacology, efficacy and safety of newer antidepressants (i.e. escitalopram, duloxetine and desvenlafaxine) in the treatment of late-life depression. To accomplish this goal, a MEDLINE and PubMed search (1966 - February 2010) was conducted for relevant articles. Animal and human studies have clearly demonstrated the effects of desvenlafaxine, duloxetine and escitalopram on monoamine reuptake transporters. The serotonergic and noradrenergic actions of desvenlafaxine and duloxetine may provide for a faster onset of antidepressant activity in the elderly, but more definitive data are needed and the clinical effects of the possible faster onset of action need to be elucidated. Duloxetine and escitalopram are extensively metabolized via cytochrome P450 (CYP) enzymes and the decreased hepatic metabolism present in many older adults should be taken into account when prescribing these medications. Duloxetine possesses the greatest likelihood of producing clinically relevant drug-drug interactions because of its inhibition of CYP2D6. All three agents must also be used cautiously in older adults with poor renal function. In terms of clinical efficacy, 14 prospective published trials involving escitalopram (n = 8) and duloxetine (n = 6) in the treatment of older adults with major depressive disorder were identified. No such studies involving desvenlafaxine were found. Of the five randomized, double-blind, controlled trials, 46% and 37% of antidepressant-treated patients were considered responders and remitters, respectively. In contrast to escitalopram, duloxetine-treated patients experienced improvements in depressive symptoms that more consistently differentiated themselves from the symptoms of placebo-treated patients. Escitalopram and duloxetine were generally well tolerated, but 5-20% and 10-27% of patients, respectively, dropped out because of medication-related adverse effects. Adverse effects experienced by older adults were generally similar to those experienced by younger adults, although indirect comparisons suggest that older adults are more likely to experience dry mouth and constipation with duloxetine and escitalopram, while orthostasis may be more common in older adults prescribed desvenlafaxine. Overall, duloxetine and escitalopram represent modestly effective treatments for late-life depression that are generally well tolerated but do produce a variety of adverse effects. Conclusions regarding desvenlafaxine cannot be made at this time because of a lack of geriatric-specific data.

Antioxidant-like effects and protective action of transcranial magnetic stimulation in depression caused by olfactory bulbectomy

We studied the effects of transcranial magnetic stimulation (TMS, 60 Hz and 0.7 mT for 4 h/day for 14 days) on oxidative and cell damage caused by olfactory bulbectomy (OBX) in Wistar rats. The levels of lipid peroxidation products and caspase-3 were enhanced by OBX, whereas it prompted a reduction in reduced glutathione (GSH) content and antioxidative enzymes activities. The treatment with TMS reverted towards normality the biomarkers indicative of oxidative stress and apoptosis. In conclusion, our data show that TMS induced a protection against cell and oxidative damage induced by OBX, as well as they support the hypothesis that oxidative stress may play an important role in depression.

Efficacy of venlafaxine compared with tricyclic antidepressants in depressive disorder: a meta-analysis

With respect to the pharmacological characteristic, venlafaxine is comparable with tricyclic antidepressants (TCAs), and venlafaxine might be comparable in efficacy. We performed a systematic review investigating the relative efficacy and tolerability of venlafaxine compared with TCAs (imipramine, clomipramine, amitriptyline, nortriptyline and desipramine). Relevant double-blind randomised trials were identified from systematic searches of electronic databases. An exact analysis of the estimated odds ratios of response of the TCA relative to venlafaxine showed no overall significance of treatment effect (P = 0.38). The odds ratios were not homogenous across studies (P = 0.0213). The average dose of venlafaxine was 103.5 mg/day and for the TCA 106.1 mg/day. An exact analysis of the estimated odds ratios of the withdrawals and side effects in the trials with a TCA relative to venlafaxine showed no overall significance of withdrawal. From our review, no significant difference in treatment effect between low dose of both venlafaxine and the TCAs could be found. In our opinion, because of the heterogeneity of the odds ratios, one cannot conclude that they are of equal efficacy.

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.

Refractory depression in late life: a review of treatment options

There seems reasonable, if depressing, agreement from studies of mixed aged subjects and elderly subjects in psychiatric settings that nonresponse or poor response to a course of an antidepressant occurs in at least one-third of depressed patients. The figure may be higher in elderly patients in general and those with poor physical health. The human cost of chronic depression is highlighted in the Medical Outcomes Study. The level of functional impairment and intereference with quality of life associated with depression was comparable with or worse than that of eight major chronic medical conditions, including diabetes, arthritis and severe coronary artery disease. The final tragedy for unremitting depression may of course be suicide.

Association study of the serotonin transporter promoter polymorphism and mirtazapine antidepressant response in major depressive disorder

Modulations of serotonergic and noradrenergic systems are thought to be critical to the therapeutic effect of most antidepressants, and their efficacies have been shown to depend on a functional polymorphism within the promoter region of the serotonin transporter gene (5-HTTLPR). Mirtazapine has a dual-action profile, combining the enhancement of the noradrenergic neurotransmitter system with specific actions on particular serotonergic receptor subtypes. The goal of this study was to elucidate whether the 5-HTTLPR polymorphism is associated with the mirtazapine antidepressant response in subjects with major depressive disorder (MDD). One hundred and one MDD patients were evaluated during 4 weeks of mirtazapine treatment. The severity of depression was assessed with the 21-item Hamilton Depression Rating scale, and the 5-HTTLPR genotypes in the patients were determined using the polymerase chain reaction. Our results showed that responses at the 2nd and 4th weeks were significantly better for the s/s genotype of the 5-HTTLPR polymorphism than for l-allele carriers. These results support our hypothesis that the response to noradrenergic and specific serotonergic antidepressants is significantly associated with the 5-HTTLPR polymorphism.

Venlafaxine vs. paroxetine in the acute phase of treatment for major depressive disorder among Han Chinese population in Taiwan

PURPOSE

Clinical studies have suggested that venlafaxine induces a higher remission rate than paroxetine. However, very few studies have evaluated relapse episodes over treatment periods longer than a few weeks, and the cut-off score of 7 on the Hamilton Rating Scale for Depression (HRSD) often used to define remission is too high. This score is associated with the high rates of social function impairment. We report on a single centre, open-label, prospective 24-week study to investigate the comparative efficacy of acute treatments with venlafaxine and paroxetine, using different definitions of response and remission rates.

METHODS

Outpatients satisfying DSM-IV criteria for major depression with a baseline HRSD17 score of at least 16 were eligible. Following baseline evaluations, the patients were assigned to receive venlafaxine 75-225 mg/day with the mean dosage 141.35 +/- 26.98 (SD) mg/day (n = 78), or paroxetine 20 mg/day (n = 92) for 24 weeks. Efficacy was assessed using the mean change in HRSD(17) score from baseline, the response rate and the remission rates based on different criteria for remission (HRSD(17) score < or = 7 or 5).

RESULTS

One hundred and seventy patients were evaluated for efficacy; 78 treated with venlafaxine and 92 with paroxetine. Over the treatment period, venlafaxine was comparable with paroxetine on most outcome measures, whereas paroxetine produced significantly higher remission rates at weeks 4, 8, 16, 20 and 24 weeks when the lower cutoff of 5 was used.

CONCLUSIONS

Venlafaxine treatment was similar to paroxetine according to the typical efficacy measures for treating outpatients with major depression. However, based on the stricter remission criterion, paroxetine might be superior to venlafaxine.

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.

Effects of Milnacipran in Animal Models of Anxiety and Memory

Serotonin (5-HT) and noradrenaline (NA) are involved in both pathogenesis and recovery from depression and anxiety. We examined the effects of acute and chronic treatment with milnacipran, a serotonin/noradrenaline reuptake inhibitors (SNRIs) antidepressant, on anxiety and memory retention in rats. Male Wistar rats received acute or chronic administration of milnacipran (12.5, 25 or 50 mg/kg) or saline (control group). The animals were separately submitted to elevated plus-maze, inhibitory avoidance and open-field tasks 1 h after injection, in the acute group, or 23 h after last injection, in the chronic group. Our results showed an anxiolytic-like effect after chronic administration of milnacipran at doses of 25 and 50 mg/kg. The treatment does not interfere in memory retention and habituation to a novel environment at any doses studied. These findings support that milnacipran, an established SNRIs antidepressant, can also be useful in the treatment of anxiety disorders.

Comparative effects of duloxetine and desipramine on sleep EEG in healthy subjects

RATIONALE

Antidepressants are known to modify human sleep patterns.

OBJECTIVES

Duloxetine is a new antidepressant with a mechanism of action involving reuptake inhibition of both serotonin (5-HT) and norepinephrine (NE). In this study, the effects of two dosing regimens of duloxetine on sleep electroencephalography (EEG) were investigated at steady-state plasma concentrations in young, healthy, male subjects.

METHODS

Placebo (n=12), desipramine (50 mg BID; n=12) and two regimens of duloxetine (80 mg QD, n=6; or 60 mg BID, n=6) were compared in a randomized, double-blind, three-period crossover study, each treatment being administered from day 1 to day 7. Sleep polygraphic recordings took place at baseline (day -1) and day 6 of each period. The Leeds sleep evaluation questionnaire (LSEQ) was also administered on the morning of day 7.

RESULTS

Both regimens of duloxetine produced a significant increase in the onset latency of REM sleep as well as a significant mean decrease in total REM sleep duration. Desipramine exhibited comparable effects. When compared to placebo, sleep continuity was significantly reduced with desipramine and duloxetine 60 mg BID whereas a significant improvement was observed with duloxetine 80 mg QD. On the LSEQ, duloxetine 80 mg QD produced a significant improvement in the "getting to sleep" subscale compared to placebo, whereas desipramine demonstrated a significant reduction (worsening) in the "quality of sleep" score versus placebo.

CONCLUSIONS

The two dose regimens of duloxetine (80 mg QD and 60 mg BID) produced a REM sleep pattern comparable to that of most antidepressant medications. Duloxetine 80 mg QD appeared to exhibit less impact upon sleep quality than duloxetine 60 mg BID in healthy subjects.

Therapy of treatment resistant depression: focus on the management of TRD with atypical antipsychotics

Treatment-resistant depression (TRD) represents a significant challenge for physicians. About one third of patients with major depressive disorder fail to experience sufficient symptom improvement despite adequate treatment. Despite this high occurrence of TRD there was no general consensus on diagnosis criteria for TRD until 1997 when researchers proposed a model of defining and staging TRD. In 1999, others defined operational criteria for the definition of TRD. Treatment of TRD is commonly separated into pharmacologic and nonpharmacologic methods. This review gives a short overview of these two methods. The nonpharmacologic methods include psychotherapy, electroconvulsive therapy, and vagus nerve stimulation. Pharmacologic methods include switching to another antidepressant monotherapy, and augmentation or combination with two or more antidepressants or other agents. This review especially focuses on the augmentation of the antidepressant therapy with atypical antipsychotics.

Remission in major depression with two antidepressant mechanisms: results from a naturalistic study

BACKGROUND

Since remission should be the goal of the treatment of depression, the aims of this study were to evaluate the rate of remission obtained with SSRIs in routine clinical practice and to assess alternative treatments with a combined mechanism of action.

METHODS

The study involved a prospective naturalistic 6-month follow-up of 44 consecutive unipolar depressed (DSM-IV) outpatients. After 6 weeks of treatment with a SSRI, patients were classified as remitted (HAM-D-17 score <==7), partial responders (>/=50% reduction in HAM-D-17 score but still higher than 7) and non-responders. In case of non-response, an antidepressant with noradrenergic action (NaA) was added to the ongoing SSRI treatment or were switched to venlafaxine in monotherapy when NaA was contraindicated.

RESULTS

At 6 weeks, eight patients (18.1%) achieved full remission, nine patients (20.5%) were partial responders and 27 (61.4%) non responders. At the end of follow-up 31.8% (n=14) of the initial sample remained remitted with SSRIs, whereas 96.2% (26/27) of previous non-responders experienced remission with the alternative treatment. Non-responders to SSRIs in monotherapy were significantly more likely to show melancholic features and to have higher HAM-D-17 scores and lower GAF scores than remitted patients with SSRIs.

LIMITATIONS

the observational and naturalistic design of the study determines inherent limitations.

CONCLUSIONS

this study showed a low remission rate with SSRIs in the long-term treatment of more severe and melancholic depression, and the benefit of using treatments with a combined mechanism of action.

Combining norepinephrine and serotonin reuptake inhibition mechanisms for treatment of depression: a double-blind, randomized study

BACKGROUND

Although several antidepressants are now available, all have limited efficacy and a delayed onset of action. The current study was undertaken as a proof of the concept that combining norepinephrine and serotonin reuptake inhibition would be more effective and act more rapidly than either drug alone.

METHODS

Inpatients with nonpsychotic unipolar major depression and a Hamilton Depression Rating Scale (HAMD) score of at least 18 after 1 week of hospitalization without antidepressant medication were randomized to 6 weeks of treatment with fluoxetine (FLX) 20 mg/day, desipramine (DMI) adjusted to an adequate plasma level, or the combination of FLX 20 mg/day and DMI, given under double-blind conditions. Twenty-four-hour DMI levels were used to rapidly adjust DMI dose to achieve a therapeutic level and to anticipate the enzyme-inhibiting effects of FLX. Treatment-resistant patients were stratified. Patients were rated with the HAMD and the Montgomery-Asberg Depression Rating Scale (MADRS).

RESULTS

Thirty-nine patients began treatment. One patient withdrew consent. The DMI-FLX combination was significantly more likely to result in remission on the MADRS than either FLX or DMI alone [53.8% vs. 7.1% and 0%, respectively; chi(2)(2) = 13.49, p =.001]. The advantage for combined treatment was not explained by history of treatment resistance or by drug plasma concentrations. Rapid response, at 1 or 2 weeks, was neither statistically nor meaningfully greater with combined treatment.

CONCLUSIONS

This study supports the hypothesis that the combination of a noradrenergic and serotonergic agent is more likely to result in remission than either selective agent alone during a 6-week treatment period.

Affective disorder and epilepsy comorbidity: implications for development of treatments, preventions and diagnostic approaches

Concepts pertaining to affective disorder and epilepsy comorbidity are contributing appreciably to improvements in patient care. Several antiepileptic treatments have become important components of the management of bipolar affective disorder. In contrast, little progress has emerged in developing clinical applications of the anticonvulsant properties of the antidepressants in the treatment of the epilepsies. The slow onset of action of the antidepressants remains a major impediment to fully effective treatment of depressive episodes. Nevertheless, studies from experimental epileptology demonstrate that the anticonvulsant effects of the antidepressants occur rapidly and as a consequence of noradrenergic and/or serotonergic activation. These studies also demonstrate that adequate initial doses of the antidepressants are essential to rapid onset of anticonvulsant action. Pharmacokinetically valid loading dose paradigms are seemingly avoided with antidepressant drugs in humans because of potential toxicities and/or patient unacceptability. However, substantial progress has been made in reducing the adverse effect liability of the antidepressants. No longer is convulsive liability considered to stem from the therapeutic mechanisms of the anti-depressants. Rather, noradrenergic and serotonergic influences have demonstrable anticonvulsant properties. Other side effects may also be separable from the anticonvulsant and antidepressive effects of antidepressive treatments. The concept that the protracted process of antidepressant-induced beta-noradrenergic down-regulation is an essential prelude to the onset of mood benefit is no longer a sustainable premise. Nevertheless, increasing evidence underlies the possibility that knowledge of serotonergic and noradrenergic regulatory processes can be used to design strategies that will hasten the onset of antidepressive action. Similar optimism pervades efforts to determine the possibility that dual inhibition of serotonin and norepinephrine transporters will hasten onset of antidepressive action. Moreover, because noradrenergic and serotonergic systems are determinants of predisposition to seizures and to dysfunctional affective episodes, augmentation strategies may also be applicable to the use of antidepressant drugs in epilepsy and to the use of antiepileptic drugs such as carbamazepine in mood disorders. Recent studies have demonstrated that, in part, the therapeutic effectiveness of carbamazepine may stem from its marked capacity to elevate serotonin concentrations in the extracellular fluid of the brain via mechanisms that differ from those of the membrane reuptake inhibitors. Evidence suggests that the epilepsies and affective disorders may arise from a multiplicity of neurobiological abnormalities. A disorder in one individual may arise via different mechanisms than a phenomenologically similar disorder in another individual. Thus, diagnostic tools are needed to make mechanistic distinctions among individuals so that treatments can be appropriately developed and selected. In terms of epileptogenesis and affective disorder progression, neuroprotective paradigms for one individual may differ from those needed for another. Moreover, diagnostic technologies that are adequate to detect genetically and/or experientially determined vulnerability before the onset of a seizure or dysfunctional affective episode may be valuable steps toward achieving goals of prevention.

Animal models of depression: are there any?

Simple tests for antidepressant-like activity, such as 5-HTP-induced syndrome or reserpine-induced hypomotility, are often mechanism-based tests, pharmacologically specific for certain known classes of therapeutically successful antidepressant agents. Many of these behavioural assays have been superseded by neurochemical techniques such as in vivo microdialysis. In contrast to these mechanistic-based models, investigators have also endeavoured to reproduce in the laboratory, factors that are believed to precipitate depression in people. It is a strong assumption in this approach that depression is a response to stress. This strategy profiles the consequences of chronic stress particularly psychosocial stress or early life events, in order to reproduce in animals the behavioural signs and pathologies associated with depression. The advances in the social psychological, clinical pathological and new areas such as neuroimaging research offer the possibility of establishing more sophisticated models for depression in animals with a broader range of biomarkers from the immunological and endocrinological to neurochemical and behavioural. Combining these novel insights with more traditional tests of depression may not only increase our understanding of the neurobiology of depression but also afford more precise and predictive preclinical models of depression. The responsiveness of different strains or genetically modified animals to stress is likely to be a key area of study. Furthermore we must look to individual differences in subjects, even within the same strain, to more fully understand why some individuals show pathological responses to stress whereas others appear unaffected. Conversely in validating our models using currently available treatments we must include the concept of non-responders so as not to disregard models that may extend therapeutic possibilities in these patients.

Dual monoamine modulation for improved treatment of major depressive disorder

The worldwide scope of depressive illness and lack of fully effective pharmacotherapy mandates significant improvements in treatment paradigms. Current antidepressant medications remain limited by poor efficacy, slow onset of action, and untoward side effects. While the introduction of serotoninspecific reuptake inhibitors (SSRIs) offered significant improvements in tolerability, no improvements in efficacy or speed of onset have been made relative to the traditional and poorly tolerated tricyclic antidepressants (TCA). The dominant efforts toward improving antidepressant medications are guided by cumulative evidence from neurochemical and clinical studies supporting the therapeutic potential of enhancing monoamine function in depression. A number of novel antidepressant drugs, including mirtazapine, milnacipran, venlafaxine, and duloxetine have been developed based on their interaction with both 5-HT and NE. Current clinical evidence suggests that these new agents may offer improved efficacy and/or faster onset of action compared with SSRIs and an improved side effect profile compared with TCAs. Potential neurobiological substrates mediating the enhanced antidepressant activity of dual reuptake inhibitors are discussed.

Essential considerations when choosing a modern antidepressant

The man-years of disability produced by depression in industrialised nations is second only to that caused by ischaemic heart disease. One in ten patients seen by a primary care physician is suffering from depressive symptoms (but neither of them may recognise it). Depression is clearly a major health problem, which can, however, be successfully treated by modern antidepressants in the overwhelming majority of cases. The problem for the primary care physician is not whether to treat but how to treat major depression. The increasing number of antidepressants from different families with different mechanisms has become an embarrassment of riches. When choosing an antidepressant, efficacy, adverse effects, safety in overdose, potential drug interactions and withdrawal effects are among the principal criteria. Although all antidepressants may appear to be equivalent in efficacy, in more severely depressed patients it has been demonstrated that dual action antidepressants, acting on both serotonin and noradrenaline, have superior efficacy to compounds acting on a single neurotransmitter. In addition certain types of depressive symptoms may respond better to one antidepressant than to another. The importance of adverse effects goes beyond patient safety and comfort and has a major influence on efficacy. If, due to adverse effects, an antidepressant is prescribed at sub-optimal doses or the patient is not compliant, even the most effective antidepressant will perform badly. The risk of suicide is inherent to depression, and to prescribe a drug which if taken in overdose can be fatal if used in a suicide attempt, is clearly unacceptable. Similarly certain antidepressants have a far greater potential for interactions with other drugs with potentially toxic effects and should be avoided in patients taking several medications. Applying these criteria globally will not designate a single "best antidepressant" but consideration of the importance of each criteria for an individual patient will help the clinician to find the antidepressant best adapted to each patient.

In the rat forced swimming test, chronic but not subacute administration of dual 5-HT/NA antidepressant treatments may produce greater effects than selective drugs

The rat forced swimming test (FST) distinguishes selective serotonin (5-HT) and selective noradrenaline (NA) reuptake-inhibitors, which respectively increase swimming and climbing behaviours. However, NA-system-mediated inhibition of 5-HT-induced swimming prevents dual 5-HT/NA reuptake-inhibition to produce concurrently climbing with swimming. Since adaptative neurochemical processes occur in the treatment of depression, we examined the influence of long-term antidepressant treatment on these interactions.

METHODS

(1) Selective [fluoxetine: 10 mg/kg; desipramine: 10 mg/kg] and non-selective [milnacipran: 40 mg/kg; mirtazapine: 20 mg/kg] antidepressants were administered subacutely (3inj) and chronically (17inj) over 16 days. (2) A subacute fluoxetine-desipramine combination (10-10 mg/kg) was administered in rats that were pre-treated with chronic-desipramine (10 mg/kg per day, 14 days). (3) NA-system-mediated interactions were further examined by combining the alpha(2)-receptor agonist clonidine (5, 10, 20, 200 microg/kg) with 10 mg/kg fluoxetine.

RESULTS

(1) Long-term treatment with either fluoxetine or desipramine does not modify the behavioural response produced by their subacute administration. (2) In contrast, whereas subacute-milnacipran increases climbing solely, chronic-milnacipran produces greater anti-immobility effects and increases both climbing and swimming behaviours. Similarly, the fluoxetine-desipramine combination produces climbing solely, but increases both climbing and swimming behaviours in animals pre-treated with chronic-desipramine. Chronic but not subacute-mirtazapine increases swimming behaviour. (3) clonidine dose-dependently antagonizes fluoxetine-induced anti-immobility effects and swimming behaviour.

CONCLUSIONS

Chronic enhancement of NA-transmission alters NA-system-mediated inhibition of 5-HT-induced behaviour in the FST, which may involve alpha(2)-receptors.

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.

Dual serotonin and noradrenaline uptake inhibitor class of antidepressants potential for greater efficacy or just hype?

Preclinical and clinical studies support the rationale that development of single molecules, which would promote serotonergic and noradrenergic neurotransmission by inhibiting simultaneously the uptake of both monoamines, would potentially result in improved antidepressant drugs. Currently, the dual inhibitors of serotonin and noradrenaline uptake are venlafaxine, milnacipran and duloxetine. Based on the preclinical studies, the three drugs do show properties of inhibiting uptake of both monoamines in vitro and in vivo in the following order of decreasing potency: duloxetine, venlafaxine and milnacipran, and all exhibit low affinity at neuronal receptors of neurotransmitters, suggesting low side-effect potential. In double-blind, controlled studies, venlafaxine and milnacipran were repeatedly shown to be as efficacious as tricyclic antidepressant drugs in treating major depressive disorder, while one double-blind, placebo-controlled trial showed the antidepressant efficacy of duloxetine. Specifically designed comparative trials of dual uptake inhibitors against the other agents are needed to establish whether the dual uptake inhibitors show improvement in efficacy, rate of responders, antidepressive effects and/or remission.

Efficacy and tolerability of venlafaxine compared with selective serotonin reuptake inhibitors and other antidepressants: a meta-analysis

BACKGROUND

In individual studies and limited meta-analyses venlafaxine has been reported to be more effective than comparator antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs).

AIMS

To perform a systematic review of all such studies.

METHOD

We conducted a systematic review of double-blind, randomised trials comparing venlafaxine with alternative antidepressants in the treatment of depression. The primary outcome was the difference in final depression rating scale value, expressed as a standardised effect size. Secondary outcomes were response rate, remission rate and tolerability.

RESULTS

A total of 32 randomised trials were included. Venlafaxine was more effective than other antidepressants (standardised effect size was -0.14, 95% Cl -0.07 to -0.22). A similar significant advantage was found against SSRIs (20 studies) but not tricyclic antidepressants (7 studies).

CONCLUSIONS

Venlafaxine has greater efficacy than SSRIs although there is uncertainty in comparison with other antidepressants. Further studies are required to determine the clinical importance of this finding.

Treatment of resistant depression by adding noradrenergic agents to lithium augmentation of SSRIs

OBJECTIVE

To examine the efficacy of second-line augmentation with noradrenergic antidepressants (NAs) in depressed patients who partially responded to lithium augmentation of selective serotonin-reuptake inhibitors (SSRIs).

CASE SUMMARY

Six patients with major depression or double depression (major depression and dysthymia) who were partially responsive to lithium and SSRI treatment were given either bupropion or desipramine, in an open clinical manner. Improvement was determined and rated by a psychiatrist based on clinical judgment guided by the Clinical Global Impression (CGI) improvement scale and by the Global Assessment of Functioning (GAF) as described in Axis V in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition.

RESULTS

Among the 6 depressed patients with partial remission (much improved in symptoms and moderate functional improvement: CGI score 2, GAF score 51-60) while taking the SSRI and lithium combination, 2 showed complete remission (very much improved in symptoms and good functioning: CGI 1, GAF 80-100) and 3 achieved near-complete remission (very much improved in symptoms and significant functional recovery: CGI 1, GAF 61-80) when given either bupropion or desipramine. One patient did not show any additional clinical or functional improvement. Second-line augmentation with bupropion was better tolerated than desipramine.

CONCLUSIONS

This clinical observation suggests that second-line augmentation with NAs may be a viable option to optimize recovery in depressed patients with a partial response to lithium augmentation of SSRIs.

Duloxetine pharmacology: profile of a dual monoamine modulator

Dysregulation within central monoaminergic systems is believed to underlie the pathology of depression. Drugs that selectively inhibit the reuptake of central monoamines have been used clinically to alleviate symptoms of depressive illnesses. Duloxetine, a novel compound currently under investigation for the treatment of depression, binds selectively with high affinity to both norepinephrine (NE) and serotonin (5-HT) transporters and lacks affinity for monoamine receptors within the central nervous system. It has been suggested that dual inhibition of monoamine reuptake processes may offer advantages over other antidepressants currently in use. In preclinical studies, duloxetine mimics many physiologic effects of antidepressants. Consistent with other antidepressants, duloxetine, by acute administration, elevates extracellular monoamine levels, while by chronic administration it does not alter basal monoamine levels. Like the selective serotonin reuptake inhibitor, fluoxetine, by microiontophoretic application, duloxetine inhibits neuronal cell firing. However, in comparison with fluoxetine, duloxetine is a more potent serotonin reuptake inhibitor. Furthermore, in behavioral experiments, duloxetine attenuates immobility in forced swim tests in animal models of depression to a greater extent than several other commonly used antidepressants. In a six-week open label uncontrolled study, duloxetine was evaluated in patients with a history of depression. Duloxetine was effective in treating depression as determined by marked reduction in Hamilton Depression Rating scores. Adverse effects reported during duloxetine treatment were minor and similar to those of other antidepressants. In an eight-week multicenter, double-blind, placebo-controlled study in patients with a major depressive disorder, duloxetine was effective as an antidepressant, particularly in patients with greater symptom severity. Only limited data are available regarding the pharmacokinetic profile of duloxetine in humans, although a half-life of 10 to 15 h has been reported. Studies conducted in healthy human subjects confirm the preclinical profile of duloxetine as an inhibitor of 5-HT and NE reuptake. Taken together, existing data suggest that duloxetine is a novel and effective antidepressant.

Augmentation of standard depression therapy

OBJECTIVE

This article reviews treatment options (eg, augmentation) for depressed patients with suboptimal clinical responses to an antidepressant.

BACKGROUND

Approximately one third of patients treated with antidepressants exhibit suboptimal or delayed clinical response to these medications. In such cases, alternative options include switching to another antidepressant or adding a second antidepressant. Augmentation strategies include addition of lithium carbonate, atypical antipsychotics, psychostimulants, thyroid hormone (triiodothyronine), pindolol, or buspirone.

CONCLUSIONS

In approximately half of all antidepressant-resistant cases of major depressive disorder, controlled clinical trials have indicated that augmentation with lithium or thyroid hormone is effective. Other reports suggest that central nervous system stimulants may augment antidepressant activity, but their use is constrained by possible abuse potential. Pindolol therapy has been shown to accelerate clinical response in some but not all studies. Finally, the favorable safety and tolerability profile of buspirone, together with its desirable anxiolytic effects, render it a sound therapeutic option in antidepressant augmentation.

Co-prescribing of SSRIs and TCAs in Australia: how often does it occur and who is doing it?

AIMS

To determine the frequency with which the selective serotonin re-uptake inhibitor (SSRI) antidepressants are used as add-on therapy to the tricyclic antidepressants (TCA) rather than as replacement therapy.

METHODS

The data analysed were profiles of prescription records by date of supply to the patient. From within the national administrative dispensing claims database, the subset eligible for social security entitlements was identified as individuals by means of their coded permanent identification numbers (PINs). Following the initial supply of an SSRI in January 1996, the subsequent 6 months dispensing of SSRI and TCA antidepressants to these individuals was examined. The main outcome measure was the proportion of individuals to whom SSRIs and TCAs were dispensed concurrently, as an indirect measure of coprescription. In instances where a patient was receiving prescriptions for SSRIs and TCAs that had been written by the one doctor only, the major specialty of the doctor was investigated.

RESULTS

55 271 PINs were dispensed 63 865 SSRI prescriptions in January 1996 which represented over half (52%) of the total community SSRI prescriptions dispensed in that month. The number of these patients meeting the criteria for coprescription of SSRIs and TCAs over the next 6 months was 2773 (5%). The coprescribing instances were highest in Queensland and the prescribers most frequently involved had psychiatry major specialty codes.

CONCLUSIONS

Among SSRI users there is a cohort of patients who, within the same time frame, are receiving supplies of a TCA, the nonselective drug that the SSRIs were designed to replace. This is indirect evidence of probable coprescription. Such combination use is of uncertain clinical and cost effectiveness, and carries additional risks. The SSRIs were included on the subsidy list in Australia on the basis of reasonable cost effectiveness as monotherapy compared with the TCAs. Our data imply that for some patients, antidepressant prescribing is inconsistent with the basis on which government subsidy was approved.

Interação medicamentosa de venlafaxina com captopril

O autor descreve um caso de interação medicamentosa, em uma senhora de 53 anos de idade, com diagnóstico de depressão e de hipertensão arterial. Com níveis pressóricos estáveis, em conseqüência de um regime dietético e de uso do captopril <FONT FACE="Symbol">-</FONT>anti-hipertensivo inibidor da enzima de conversão da angiotensina <FONT FACE="Symbol">-</FONT>, passou a apresentar constantes descompensações do seu quadro clínico, com elevações da tensão arterial (TA), logo após a introdução da venlafaxina no seu esquema terapêutico. Esse medicamento é um potente antidepressivo de última geração, que atua no sistema nervoso central (SNC), inibindo a recaptação de serotonina e noradrenalina. Demonstra a interação pelo monitoramento da TA e aplicação do instrumento de Naranjo. Descreve as condições clínicas gerais da paciente e sua evolução, e discute os mecanismos prováveis que conduziram a interação pela hipótese que envolve o aumento de noradrenalina nos terminais sinápticos, o sistema renina-angiotensina e a bradicinina, concluindo que a venlafaxina agiu como antagonista, de modo indireto, sobre os efeitos hipotensores do captopril.

Effects of sustained administration of the serotonin and norepinephrine reuptake inhibitor venlafaxine: I. in vivo electrophysiological studies in the rat

The effect of a 21-day treatment with the dual 5-HT and NE reuptake blocker venlafaxine (delivered s.c. by osmotic minipumps) was assessed on the time required for a 50% recovery (RT(50)) of the firing activity of dorsal hippocampus CA(3) pyramidal neurons from the suppression induced by microiontophoretic applications of 5-HT and NE. The RT(50) values for 5-HT were increased by both 10 and 40 mg/kg/day regimens of venlafaxine, whereas those for NE were increased only by the 40 mg/kg/day regimen, indicative of a greater potency of venlafaxine in blocking 5-HT reuptake. The sensitivity of the postsynaptic 5-HT(1A) and alpha(2)-adrenergic receptors was altered by neither regimen of venlafaxine. Using a paradigm by which the 5-HT(1A) antagonist WAY 100635 can induce a disinhibition of firing activity of CA(3) pyramidal neurons, it was demonstrated that the high, but not the low, dose of venlafaxine led to an enhanced tonic activation of postsynaptic 5-HT(1A) receptors in the dorsal hippocampus. The duration of the suppressant effect of the firing activity of CA(3) hippocampus pyramidal neurons produced by the electrical stimulation of the ascending 5-HT pathway was significantly reduced when the frequency of the stimulation was enhanced from 1 Hz to 5 Hz in control rats and in rats treated with 10 mg/kg/day, but not with 40 mg/kg/day of venlafaxine. Hence, venlafaxine induced a desensitization of the terminal 5-HT(1B) autoreceptor only at the high dose. A 2-day treatment with 10 mg/kg/day of venlafaxine induced a suppression of the firing activity of 5-HT neurons of the dorsal raphe. The firing activity of these neurons was back to control level in rats that had been treated for 21 days with the same dose of venlafaxine. The suppressant effect of the i.v. administration of the 5-HT autoreceptor agonist LSD on the firing activity of dorsal raphe 5-HT neurons was reduced in rats that had been treated for 21 days with 10 mg/kg/day of venlafaxine. A 2-day treatment with 40 mg/kg/day of venlafaxine, unlike the 10 mg/kg/day regimen, induced a marked suppression of the firing activity of locus coeruleus NE neurons. However, in contrast to 5-HT neurons, NE neurons did not recover their firing activity after a 21-day treatment. Taken together, the results from this study indicate that the low dose of venlafaxine blocked selectively the reuptake of 5-HT, whereas the high dose blocked the reuptake of both 5-HT and NE. Moreover, an enhancement of serotonergic neurotransmission by venlafaxine was only achieved under conditions whereby the desensitization of the terminal 5-HT(1B) autoreceptor is appended to that of the somatodendritic 5-HT(1A) receptor.

Effect of acute treatment with YM992 on extracellular norepinephrine levels in the rat frontal cortex

The effects of acute treatment with (S)-2-[[(7-fluoroindan-4-yl)oxy]methyl]morpholine monohydrochloride (YM992), venlafaxine, fluoxetine and citalopram on extracellular norepinephrine levels were examined in the rat frontal cortex by in vivo microdialysis. YM992 (3, 10, 30 mg/kg, i.p.) dose-dependently increased extracellular norepinephrine levels (3-fold at 10 mg/kg, 5. 5-fold at 30 mg/kg). While venlafaxine and 30 mg/kg fluoxetine also produced significant increases in norepinephrine levels, 30 mg/kg citalopram had no effect. The combined administration of MDL100,907 (a selective 5-HT(2A) receptor antagonist) and citalopram did significantly increase norepinephrine levels compared with either saline or citalopram treatment. Therefore, a synergistic effect due to 5-HT reuptake inhibition and 5-HT(2A) receptor antagonism of YM992 may partly contribute to the increase of extracellular norepinephrine levels. YM992 enhances the neurotransmission of not only 5-HT system but also norepinephrine, and as such may have a preclinical profile different from that of a selective serotonin reuptake inhibitor.

Add-on polytherapy with antidepressants and its significance in inpatients with major depression

Add-on polytherapy with antidepressant agents was reviewed in 42 inpatients with major depression diagnosed according to the ICD-10 criteria. Twenty-eight (67.7%) patients were treated with two or more antidepressants. The most frequent combination consisted of a tricyclic antidepressant and a non-tricyclic antidepressant. Nineteen (67.8%) patients of the polytherapy group were treated with a dosage equivalent to 150 mg/day of tricyclic antidepressant. Clinically, not every patient with major depression can tolerate the adverse side effects induced by an effective dose of a single tricyclic antidepressant. From this viewpoint, add-on polytherapy with antidepressants could be one of the treatment options, especially for such intolerant patients.

Risk of adverse events with the use of augmentation therapy for the treatment of resistant depression

Augmentation therapy is used for those situations where a patient's depression is either treatment-resistant, or partially and/or insufficiently responsive to treatment. It also may be used to attempt to induce a more rapid treatment response. Using drugs together may increase the risk of adverse effects, through potentiation of existing adverse effects or alterations in plasma concentrations of the drug. It is important that clinicians are aware of potential risks of augmentation therapy. Lithium augmentation of a tricyclic antidepressant is relatively well tolerated and the dangers are no greater than using these medications on their own. There are also no reports of serious adverse events when lithium is added to a monoamine oxidase inhibitor. With lithium augmentation of selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitor (SSRI) therapy there have been case reports of the development of a central serotonin syndrome, and thus caution must exercised. A serious concern when using a tricyclic antidepressant to augment an SSRI is the effect of the SSRI on the cytochrome P450 system and the resulting significant increase in tricyclic antidepressant blood concentrations. Augmentation with thyroid hormones appears to be well tolerated and effective. Case reports and open studies indicate that augmentation with buspirone and the psychostimulants, carbamazepine and valproic acid (valproate sodium) is effective and results in minimal adverse effects. However, there is no empirical evidence supporting these results. Recent work supports the tolerability and efficacy of pindolol augmentation. Considerable caution should be exercised when combining psychotropic drugs. The practitioner should only do so with a full knowledge of the compounds involved and their pharmacological properties.

Blockade of 5-hydroxytryptamine and noradrenaline uptake by venlafaxine: a comparative study with paroxetine and desipramine

1. Venlafaxine is an antidepressant agent which blocks in vitro the reuptake of both 5-HT and NA. The present in vivo electrophysiological studies were undertaken, in the rat, to compare the effects of venlafaxine on 5-HT and NA reuptake to those of the selective 5-HT reuptake inhibitor paroxetine and the selective NA reuptake inhibitor desipramine. 2. Administered acutely, venlafaxine dose-dependently prolonged the time required for a 50% recovery (RT50) of the firing activity of dorsal hippocampus CA3 pyramidal neurons from the suppression induced by microiontophoretic applications of 5-HT and NA. Venlafaxine and paroxetine increased with a similar potency the RT50 values for 5-HT, while desipramine was more potent than venlafaxine at increasing the RT50 values for NA. Moreover, venlafaxine demonstrated a greater potency at increasing the RT50 values for 5-HT compared to that of NA. 3. A two-day treatment with venlafaxine (delivered s.c. by osmotic minipumps) increased the RT50 values for both 5-HT and NA applications. The RT50 values for 5-HT were significantly increased at a dose of 10 mg kg(-1) day(-1), whereas those for NA were increased at a dose of 20 mg kg(-1) day(-1), consistent with the data obtained following the acute administration of venlafaxine. 4. Taken together, these results indicate that, in vivo, venlafaxine blocks both reuptake processes, with a potency greater for the 5-HT than for the NA reuptake process. This dual action, combined with the differential potency of venlafaxine, might constitute the biological substratum responsible for its apparent unique clinical efficacy in major depression.

Neurochemical and behavioral characterization of potential antidepressant properties of indeloxazine hydrochloride

The potential antidepressant properties of indeloxazine hydrochloride were examined in vitro and in vivo. Indeloxazine showed preferential affinity for both [3H] citalopram (Ki: 22.1 nM) and [3H]nisoxetine binding sites (Ki: 18.9 nM) in membranes of the rat cerebral cortex. In microdialysis studies, intraperitoneal injection of indeloxazine (3 and 10 mg/kg) dose-dependently increased the extracellular level of both serotonin and norepinephrine in rat frontal cortex of freely moving rats. Amitriptyline was almost equivalent to indeloxazine in these two assays with the exception of a much weaker effect on extracellular serotonin levels. Spontaneous [3H]serotonin release from rat cortical synaptosomes was significantly enhanced by indeloxazine (10-1000 nM). In behavioral studies, indeloxazine increased the number of wheel rotations in forced swimming tests in both ICR mice (50 mg/kg, p.o.) and SAMP8//YAN, a substrain of senescence-accelerated mouse (20 and 30 mg/kg, p.o.). Indeloxazine (3-10 mg/kg p.o.) also inhibited the incidence of muricide in raphe-lesioned rats. These results suggest that indeloxazine is an inhibitor of serotonin and norepinephrine uptake and has potential antidepressant properties. In addition, the drug-induced enhancement of serotonin release may contribute to its potent effects on the serotonergic system in vivo.

Economic consequences of selective serotonin reuptake inhibitor use with drugs also metabolized by the cytochrome P-450 system

Administration of selective serotonin reuptake inhibitors (SSRIs) may increase plasma concentrations of concomitant medications that are also metabolized by the cytochrome P-450 system (CYP-450), in particular by the 2D6 and 3A4 isoenzymes. This may lead to side effects or other clinical events that might be expected to incur higher health-care expenditures. The purpose of this study was to assess whether there was a difference in expenditures during the first 90 days of SSRI therapy with paroxetine or sertraline versus fluoxetine in patients who were also receiving a stable dosage of a nonpsychiatric drug also metabolized by the CYP-450 2D6 or 3A4 isoenzyme systems. A sample of 2445 patients who initiated therapy with an SSRI while receiving a stable dosage of a nonpsychiatric drug was obtained from a private insurance claims database. Multivariate regression techniques were used to estimate total health-care expenditures in the first 90 days after receiving a prescription for an SSRI. After adjusting for nonrandom SSRI prescription patterns and controlling for observable and unobservable characteristics that might correlate with SSRI selection, total health-care expenditures were 95% higher for patients initiating SSRI therapy with sertraline or paroxetine compared with fluoxetine. Results suggest that there are cost differences between SSRIs during concomitant therapy with drugs also metabolized by the CYP-450 system. To determine whether there are additional differences in expenditures across SSRIs, future research should focus on (1) simultaneous initiation of SSRI therapy and a nonpsychiatric drug also metabolized by the CYP-450 enzyme system, and (2) addition of nonpsychiatric drug therapy to stable SSRI therapy. Relationships between additional expenditures, drug interactions, and clinical outcomes should also be assessed directly using medical records and patient interview data that are not available in claims-based files.

A review of the use of augmentation therapy for the treatment of resistant depression: implications for the clinician

OBJECTIVE

To critically review the literature on augmentation therapy in resistant depression in order to assist the clinician to make a reasoned choice. Augmentation therapy is defined as the addition of a second agent to an existing antidepressant regimen with the aim of achieving improved clinical response.

METHOD

The available literature which related specifically to currently popular augmentation strategies in treatment resistant depression for the past 20 years was examined. The scientific evidence supporting the efficacy of these regimens and their safety was reviewed.

RESULTS

Considerable research on lithium augmentation has been undertaken, and on triiodothyronine augmentation to a lesser degree. A number of other drugs have been trialed as augmentation agents with claims of success; however, most of the evidence supporting these agents is anecdotal and in the form of case reports. There are very few well-performed double-blind placebo-controlled studies of augmentation therapy.

CONCLUSIONS

Because of possible complex pharmacodynamic and pharmacokinetic interactions, augmentation therapy is not without its potential complications. Lithium augmentation of tricyclic antidepressants can be recommended as a safe and effective strategy and there is a body of scientific evidence supporting the addition of T3 as an effective augmentation agent. Recent research with pindolol augmentation of selective serotonin re-uptake inhibitors (SSRIs) is encouraging, but these findings require replication. There is no empirical evidence supporting buspirone, carbamazepine, sodium valproate, methylphenidate or amphetamine as effective augmentation agents, or that adding a tricyclic to a SSRI has usefulness in relieving depressive symptoms. There is a need for considerable research in this area, with more prospective well-controlled placebo studies.

Selective serotonin reuptake inhibitor-induced serotonin syndrome: review

The selective pharmacology of the selective serotonin reuptake inhibitors (SSRIs) results in a lower potential for pharmacodynamic drug interactions relative to other antidepressants such as the tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs). However, the SSRIs have been implicated in the development of the serotonin syndrome--a potentially life-threatening complication of treatment with psychotropic drugs. The syndrome is produced most often by the concurrent use of two or more drugs that enhance central nervous system serotonin activity and often goes unrecognized because of the varied and nonspecific nature of its clinical features. The serotonin syndrome is characterized by alterations in cognition (disorientation, confusion), behavior (agitation, restlessness), autonomic nervous system function (fever, shivering, diaphoresis, diarrhea), and neuromuscular (ataxia, hyperreflexia, myoclonus) activity. The difference between this syndrome and the occurrence of adverse effects caused by serotonin reuptake inhibitors alone is the clustering of the signs and symptoms, their severity, and their duration. There are important pharmacokinetic interactions between SSRIs and other serotonergic drugs due principally to their effects on the cytochrome P450(CYP) isoenzymes, the potential for which varies widely amongst the SSRI group, which may increase the likelihood of a pharmacodynamic interaction. The exceptionally long washout period required after fluoxetine discontinuation may cause additional problems and/or inconvenience. Patients with serotonin syndrome usually respond to discontinuation of drug therapy and supportive care alone, but they may also require treatment with antiserotonergic agent such as cyproheptadine, methysergide, and/or propranolol. To reduce the occurrence, morbidity, and mortality of the serotonin syndrome, it must be both prevented by prudent pharmacotherapy and given prompt recognition when it is present.

Electrophysiological effects of fluoxetine and duloxetine in the dorsal raphe nucleus and hippocampus

The cellular electrophysiological effects of duloxetine (LY248686), a dual serotonin (5-hydroxytryptamine, 5-HT) and norepinephrine reuptake inhibitor, and the selective serotonin reuptake inhibitor fluoxetine were compared on spontaneously active neurons in the dorsal raphe nucleus and the hippocampus of chloral hydrate-anesthetized male rat. Systemic intravenous administration of duloxetine or fluoxetine inhibited dorsal raphe nucleus cell firing in a dose-dependent manner; duloxetine suppressed cell firing at significantly lower doses (ED100 1.4 +/- 0.3 mg/kg) than fluoxetine (ED100 10.0 +/- 2.0 mg/kg). In the hippocampus, microiontophoretic application of duloxetine or fluoxetine (0.01 M, pH 5.5; 5-40 nA) produced minimal inhibition of cell firing. When duloxetine was co-applied with 5-HT, the recovery response (RT50 values) of hippocampal pyramidal neurons to 5-HT application was not altered. In contrast, co-application of fluoxetine with 5-HT at the same iontophoretic currents significantly increased (59%) the RT50 values produced by 5-HT application alone. This physiological and pharmacological study contributes to understanding the cellular mechanisms of these agents which may be useful in the treatment of depression.

Introduction

In the past serendipity and good clinical observation were essential for the discovery of new drug treatments for mental disorders. Today, neurochemical and pharmacological research allows development of compounds starting from hypothesis on the origin of the disorders and the actions of available drugs. The new compounds are cleaner from the pharmacological point of view, more specific and therefore with less undesired effects. Venlafaxine is one of these drugs and provides antidepressant efficacy in a broad range of depressed patients, including the most severe ones, with a good safety and tolerability profile.