Efficacy and tolerability of milnacipran: an overview

Ten years of maintenance treatment of severe melancholic depression in an adult woman including discontinuation experiences

BACKGROUND

There are only few publications on long-term treatments for major depressive disorder (MDD) lasting 5 years or longer. Most clinical controlled trials lasted no longer than 2 years and some recent studies suggested an advantage of cognitive behavioral therapy (CBT) over antidepressants in relapse prevention of MDD.

METHODS

Exclusively outpatient "real world" treatment of severe melancholia, prospectively documented over 10 years with different serial treatment strategies, discontinuation phenomena and complications.

METHODS

Compared to CBT, agomelatine, mirtazapine, bupropion and high-dose milnacipran, high-dose venlafaxine (extended-release form, XR) was effective, even sustainably. Asymptomatic premature ventricular contractions (PVCs) were found at the beginning of the treatment of the MDD, which initially led to the discontinuation of high-dose venlafaxine (300 mg daily). Even the various treatment strategies mentioned above were unable to compensate for or prevent the subsequent severe deterioration in MDD (2 rebounds, 1 recurrence). Only the renewed use of high-dose venlafaxine was successful. PVC no longer occurred and the treatment was also well tolerated over the years, with venlafaxine serum levels at times exceeding 5 times the recommended upper therapeutic reference level (known bupropion-venlafaxine interaction, otherwise 2.5 to 3-fold increase with high-dose venlafaxine alone). During dose reduction or after gradual discontinuation of high-dose venlafaxine, rather mild withdrawal symptoms occurred, but as described above, also two severe rebounds and one severe recurrence happened.

DISCUSSION

This long-term observation supports critical reflections on the discontinuation of successful long-term treatment with antidepressants in severe MDD, even if it should be under "the protection" of CBT. The PVC seemed to be more related to the duration of the severe major depressive episode than to the venlafaxine treatment itself. A particular prospective observation of this longitudinal case study is that relapses (in the sense of rebounds) during or after previous venlafaxine tapering seemed to herald the recurrence after complete recovery. Remarkably, neither relapses nor recurrence could be prevented by CBT.

CONCLUSION

In this case, high-dose venlafaxine has a particular relapse-preventive (and "recurrence-preventive") effect with good long-term tolerability.

The broad spectrum of comorbid depression: implications for treatment

There is a high rate of depression in patients with medical or other psychiatric disorders. This comorbid depression is associated with an increased morbidity and mortality from medical illness, poor compliance with treatment, a worsening of somatic symptoms, and often a decrease in functional status. Several recent studies have demonstrated that comorbid depression is highly treatable and that effective treatment often enhances patients' adaptive coping with medical illness. However, when choosing antidepressant therapy, care must be taken to evaluate the patient's illness fully and to avoid potential drug-drug interactions and drug-related illness. This review investigates the use of antidepressants in depressed patients with medical and psychiatric disorders and their effect on prognosis and morbidity, and suggests that there is a place for the use of antidepressant medications in the treatment of comorbid conditions. Generally, the greater safety and tolerability of the selective serotonin reuptake inhibitors provides improved options for the treatment of depression in the medically and psychiatrically ill.

Serotonin and Norepinephrine Reuptake Inhibitors

This chapter covers antidepressants that fall into the class of serotonin (5-HT) and norepinephrine (NE) reuptake inhibitors. That is, they bind to the 5-HT and NE transporters with varying levels of potency and binding affinity ratios. Unlike the selective serotonin (5-HT) reuptake inhibitors (SSRIs), most of these antidepressants have an ascending rather than a flat dose-response curve. The chapter provides a brief review of the chemistry, pharmacology, metabolism, safety and adverse effects, clinical use, and therapeutic indications of each antidepressant. Venlafaxine, a phenylethylamine, is a relatively weak 5-HT and weaker NE uptake inhibitor with a 30-fold difference in binding of the two transporters. Therefore, the drug has a clear dose progression, with low doses predominantly binding to the 5-HT transporter and more binding of the NE transporter as the dose ascends. Venlafaxine is metabolized to the active metabolite O-desmethylvenlafaxine (ODV; desvenlafaxine) by CYP2D6, and it therefore is subject to significant inter-individual variation in blood levels and response dependent on variations in CYP2D6 metabolism. The half-life of venlafaxine is short at about 5 h, with the ODV metabolite being 12 h. Both parent compound and metabolite have low protein binding and neither inhibit CYP enzymes. Therefore, both venlafaxine and desvenlafaxine are potential options if drug-drug interactions are a concern, although venlafaxine may be subject to drug-drug interactions with CYP2D6 inhibitors. At low doses, the adverse effect profile is similar to an SSRI with nausea, diarrhea, fatigue or somnolence, and sexual side effects, while venlafaxine at higher doses can produce mild increases in blood pressure, diaphoresis, tachycardia, tremors, and anxiety. A disadvantage of venlafaxine relative to the SSRIs is the potential for dose-dependent blood pressure elevation, most likely due to the NE reuptake inhibition caused by higher doses; however, this adverse effect is infrequently observed at doses below 225 mg per day. Venlafaxine also has a number of potential advantages over the SSRIs, including an ascending dose-antidepressant response curve, with possibly greater overall efficacy at higher doses. Venlafaxine is approved for MDD as well as generalized anxiety disorder, social anxiety disorder, and panic disorder. Desvenlafaxine is the primary metabolite of venlafaxine, and it is also a relatively low-potency 5-HT and NE uptake inhibitor. Like venlafaxine it has a favorable drug-drug interaction profile. It is subject to CYP3A4 metabolism, and it is therefore vulnerable to enzyme inhibition or induction. However, the primary metabolic pathway is direct conjugation. It is approved in the narrow dose range of 50-100 mg per day. Duloxetine is a more potent 5-HT and NE reuptake inhibitor with a more balanced profile of binding at about 10:1 for 5HT and NE transporter binding. It is also a moderate inhibitor of CYP2D6, so that modest dose reductions and careful monitoring will be needed when prescribing duloxetine in combination with drugs that are preferentially metabolized by CYP2D6. The most common side effects identified in clinical trials are nausea, dry mouth, dizziness, constipation, insomnia, asthenia, and hypertension, consistent with its mechanisms of action. Clinical trials to date have demonstrated rates of response and remission in patients with major depression that are comparable to other marketed antidepressants reviewed in this book. In addition to approval for MDD, duloxetine is approved for diabetic peripheral neuropathic pain, fibromyalgia, and musculoskeletal pain. Milnacipran is marketed as an antidepressant in some countries, but not in the USA. It is approved in the USA and some other countries as a treatment for fibromyalgia. It has few pharmacokinetic and pharmacodynamic interactions with other drugs. Milnacipran has a half-life of about 10 h and therefore needs to be administered twice per day. It is metabolized by CYP3A4, but the major pathway for clearance is direct conjugation and renal elimination. As with other drugs in this class, dysuria is a common, troublesome, and dose-dependent adverse effect (occurring in up to 7% of patients). High-dose milnacipran has been reported to cause blood pressure and pulse elevations. Levomilnacipran is the levorotary enantiomer of milnacipran, and it is pharmacologically very similar to the racemic compound, although the side effects may be milder within the approved dosing range. As with other NE uptake inhibitors, it may increase blood pressure and pulse, although it appears to do so less than some other medications. All medications in the class can cause serotonin syndrome when combined with MAOIs.

Levomilnacipran (Fetzima)

In July 2013, the US Food and Drug Administration approved levomilnacipran extended release (ER; Fetzima), a serotonin-norepinephrine reuptake inhibitor, for the treatment of adults with major depressive disorder. Levomilnacipran is an active enantiomer of the racemic drug milnacipran that is currently approved in the United States for the treatment of fibromyalgia. This article provides an overview of the mechanism of action, pharmacokinetic properties, clinical efficacy, safety, and tolerability of levomilnacipran ER. Relevant information was identified through a search of databases using the key word levomilnacipran. Additional information was obtained from fda.gov, by a review of the reference lists of identified articles, and from posters and abstracts from scientific meetings. Levomilnacipran ER, dosed once daily, is generally well tolerated and has demonstrated favorable effects compared to placebo in clinical trials of patients with major depressive disorder. The increased potency for norepinephrine reuptake inhibition is a characteristic that may represent a novel contribution for levomilnacipran. Additional studies comparing levomilnacipran ER to other commonly prescribed antidepressants are needed to further evaluate its place in therapy.

Effect of competition bias in safety signal generation: analysis of a research database of spontaneous reports in France

BACKGROUND

Automated disproportionality analysis of spontaneous reporting is increasingly used routinely. It can theoretically be influenced by a competition bias for signal detection owing to the presence of reports related to well-established drug-event associations.

OBJECTIVE

The aim of the study was to explore the effects of competition bias on safety signals generated from a large spontaneous reporting research database.

METHODS

Using the case/non-case approach in the French spontaneous reporting research database, which includes data of reporting in France from January 1986 to December 2001, the effects of the competition bias were explored by generating safety signals associated with six events of interest (gastric and oesophageal haemorrhages, central nervous system haemorrhage and cerebrovascular accidents, ischaemic coronary disorders, migraine headaches, muscle pains, and hepatic enzymes and function abnormalities) before and after removing from the database reports relating to drugs known to be strongly associated with these events, whether they constituted cases or non-cases. As this study was performed on a closed database (last data entered 31 December 2001), potential signals unmasked by removal were considered as real signals if no or only incomplete knowledge about the association was available from the literature before 1 January 2002.

RESULTS

For gastric and oesophageal haemorrhages, after removing reports involving antithrombotic agents or NSAIDs, three potential signals were unmasked (prednisone, rivastigmine and isotretinoin). For central nervous system haemorrhage and cerebrovascular accidents, after removing reports involving antithrombotic agents, three potential signals were unmasked (ethinylestradiol, interferon-α-2B and methylprednisolone). For ischaemic coronary disorders, after removing reports involving anthracyclines, bleomycine, anti-HIV drugs or triptans, one potential signal was unmasked (ondansetron). For migraine headaches, after removing reports involving nitrates, calcium channel blockers, opioid analgesics or intravenous immunoglobulins, six potential signals were unmasked (ammonium chloride, leflunomide, milnacipran, montelukast, proguanil and pyridostigmine). For muscle pains, after removing reports involving statins or fibrates, seven potential signals were unmasked (hydroxychloroquine, lactulose, levodopa in combination with dopadecarboxylase inhibitor, nevirapine, nomegestrol, ritonavir and stavudine). Finally, for hepatic enzymes and function abnormalities, after removing reports involving NSAIDs, anilides, antituberculosis drugs, antiepileptics, ketoconazole, tacrine, or amineptine, two potential signals were unmasked (caffeine, metformin). Of all these unmasked potential signals, ten appeared non/incompletely documented as at 1 January 2002 and were considered as real signals, with three of these later being confirmed by the literature and finally considered as true positives (isotretinoin, methylprednisolone and milnacipran).

CONCLUSION

This study confirms that a competition bias can occur when performing safety signal generation in spontaneous reporting databases. The minimization of this bias could lead to previously masked signals being revealed.

Plasma levels of milnacipran and its effectiveness for the treatment of chronic pain in the orofacial region

OBJECTIVES

This study was performed to assess the relationship between plasma levels of milnacipran and its analgesic/antidepressive effect in patients with chronic orofacial pain treated with this drug.

METHODS

A total of 44 patients took milnacipran for 12 weeks. Patients were assessed for their pain and depressive symptoms using the visual analog scale (VAS) and Hamilton Depression Rating Scale, respectively. The plasma milnacipran level was also assessed at week 12.

RESULTS

Forty patients completed study treatment and were included in the analysis. In these patients, the VAS score at week 12 significantly decreased from the baseline score (t = 5.15, p < 0.0001). The dose of milnacipran was positively correlated in a linear manner with the plasma level of the drug (Y = 44.86 + 0.33X, r = 0.54, R(2)  = 0.29, p = 0.0004). A quadratic regression curve was plotted between the percentage of decrease in the VAS score and plasma milnacipran level (Y = 27.39 + 0.76X - 0.008X(2) , p = 0.048, r = 0.40, R(2)  = 0.16). On the other hand, no significant relationship was noted between the percentage of decrease in the Hamilton Depression Rating Scale score and plasma milnacipran level.

CONCLUSION

The analgesic effect of milnacipran was suppressed in the presence of the plasma level of the drug outside the therapeutic range, whereas its antidepressant effect was not affected by its plasma level.

Cardiotoxicity and serotonin syndrome complicating a milnacipran overdose

Milnacipran is a selective serotonin and norepinephrine reuptake inhibitor, recently approved for use in the USA for treatment of fibromyalgia. This case report describes a 59-year-old woman who ingested 3,000 mg of milnacipran in a suicide attempt. Following the ingestion, she became obtunded and developed autonomic instability. She required mechanical ventilation, treatment for hypertension, and then ultimately vasopressor support for refractory hypotension. In addition, she developed a transient, acute cardiac dysfunction with global hypokinesis and an ejection fraction of 30%. Resolution of the cardiac dysfunction was documented on repeat echocardiogram 2 days after the initial study. This was confirmed by cardiac catheterization performed 4 days after the acute ingestion in which coronary arteriogram was normal and left ventricular ejection fraction was 70%. Acute overdose was confirmed by quantification of plasma milnacipran concentration of 8,400 ng/mL obtained 5 h post-ingestion. To our knowledge, this represents the first case of cardiac toxicity complicating a milnacipran overdose in the medical literature.

Rapid improvement of depressive symptoms in suicide attempters following treatment with milnacipran and tricyclic antidepressants - a case series

Suicide is a serious social problem in many countries, including Japan. The majority of people who commit suicide suffer from depression. Suicide attempt patients suffering from serious physical injuries are initially treated in hospital emergency departments. The present post hoc analysis examined data from patients admitted to an emergency hospital for treatment of physical injuries, resulting from a suicide attempt, and initial psychiatric treatment for depression and prevention of future suicide attempts. The effects on depressive symptoms were studied in two groups of patients using the 17-item Hamilton depression scale (HAMD). One group (n = 6) had received intravenous tricyclic antidepressants (TCA) (amitriptyline or clomipramine) while the other group (n = 7) had been treated orally with milnacipran, a serotonin and norepinephrine reuptake inhibitor antidepressant. Prior to treatment the four highest scoring items on the HAMD scale were the same in both groups namely, item 1 (depressed mood), item 3 (suicidality), item 7 (interest in work and activities), and item 10 (psychic anxiety). After 1 week of treatment, mean global HAMD scores were significantly reduced in both groups. Treatment resulted in a significant reduction of five HAMD items in the TCA group, whereas in the milnacipran group 12 HAMD items were significantly reduced. Suicidality (item 3) was significantly improved by 1 week treatment with milnacipran, but not by TCAs. Milnacipran rapidly improved a wide range of depressive symptoms, including suicidality within the first week. The improvement with milnacipran would appear to be, at least, equivalent to that achieved with TCAs, possibly affecting a wider range of symptoms. Since milnacipran has been shown in comparative studies to be better tolerated than TCAs, this antidepressant offers an interesting option for the treatment of suicidal patients in an emergency setting.

Milnacipran: a unique antidepressant?

Tricyclic antidepressants (TCAs) are among the most effective antidepressants available, although their poor tolerance at usual recommended doses and toxicity in overdose make them difficult to use. While selective serotonin reuptake inhibitors (SSRIs) are better tolerated than TCAs, they have their own specific problems, such as the aggravation of sexual dysfunction, interaction with coadministered drugs, and for many, a discontinuation syndrome. In addition, some of them appear to be less effective than TCAs in more severely depressed patients. Increasing evidence of the importance of norepinephrine in the etiology of depression has led to the development of a new generation of antidepressants, the serotonin and norepinephrine reuptake inhibitors (SNRIs). Milnacipran, one of the pioneer SNRIs, was designed from theoretic considerations to be more effective than SSRIs and better tolerated than TCAs, and with a simple pharmacokinetic profile. Milnacipran has the most balanced potency ratio for reuptake inhibition of the two neurotransmitters compared with other SNRIs (1:1.6 for milnacipran, 1:10 for duloxetine, and 1:30 for venlafaxine), and in some studies milnacipran has been shown to inhibit norepinephrine uptake with greater potency than serotonin (2.2:1). Clinical studies have shown that milnacipran has efficacy comparable with the TCAs and is superior to SSRIs in severe depression. In addition, milnacipran is well tolerated, with a low potential for pharmacokinetic drug-drug interactions. Milnacipran is a first-line therapy suitable for most depressed patients. It is frequently successful when other treatments fail for reasons of efficacy or tolerability.

Effectiveness of milnacipran for the treatment of chronic pain in the orofacial region

OBJECTIVES

The effect of milnacipran for the treatment of chronic pain in the orofacial region, including burning mouth syndrome (BMS) and atypical odontalgia (AO), was assessed while accounting for the influence of concurrent depressive symptoms on the pain-relieving effect.

METHODS

Milnacipran was administered for 12 weeks to 36 patients with chronic pain in the orofacial region (3 men and 29 women, aged between 22 and 76 years with a mean age of 59 years). Of those patients, 22 and 10 patients had BMS and AO, respectively. The initial dose of milnacipran was 15 mg a day, and the dose was raised up to 100 mg a day. Pain was assessed using the visual analog scale, and symptoms of depression were evaluated using the Hamilton Depression Rating Scale at baseline and at weeks 1, 2, 4, 6, 8, 10, and 12 of the study treatment.

RESULTS

Data from 32 patients who completed the study were included in the analysis. The visual analog scale score significantly decreased after the 12-week treatment, and it showed a similar time course of decline irrespective of concurrent depressive symptoms during the 12 weeks.

CONCLUSIONS

Treatment with milnacipran resulted in a significant improvement of chronic pain in the orofacial region irrespective of concurrent symptoms of depression. The present results suggested that milnacipran may be an effective agent for treatment of such disorders.

Duloxetine-induced hypomania: case report and brief review of the literature on SNRIs-induced mood switching

Manic switching during antidepressant treatment has been reported with every class of antidepressant drugs. Serotonin-noradrenaline reuptake inhibitors (SNRIs) have been increasingly used for the treatment of unipolar and bipolar depression and are well tolerated and sufficiently effective because of their dual mechanism of action. A case of duloxetine-induced hypomania in a non-bipolar patient is presented, and a brief review of all cases of SNRIs' induced mania and hypomania has been carried out. The available data suggest that SNRIs, especially venlafaxine, can induce mood switching in patients with bipolar depression and in certain patients with unipolar depression, but the potential of duloxetine and milnacipran to induce manic or hypomanic symptoms cannot be disregarded. Switching appears to be dose-related and treatment initiation with lower doses and upward titration when needed may be preferable in selected cases and may help minimizing the risk of mood switching.

Fatal intoxication with milnacipran

The antidepressant milnacipran is a double serotonin/noradrenalin reuptake inhibitor. The low reported incidence of intoxication indicates excellent tolerance in comparison with tricyclic and second generation antidepressants. We report a fatal intoxication associating milnacipran, at blood levels (femoral=21.5 mg/l, cardiac=20 mg/l) 40-fold higher than the usual treatment concentration, and six other molecules (fluoxetine, norfluoxetine, sertraline, cyamemazine, nordazepam and oxazepam) at therapeutic levels. To the best of our knowledge, this is the first reported fatal intoxication involving milnacipran.

Piloerection induced by replacing fluvoxamine with milnacipran

AIMS

To present a case of piloerection after replacing fluvoxamine maleate with milnacipran hydrochloride, and to analyse this effect based on receptor occupancy theory.

METHODS

A 40-year-old female with a 3-year history of panic disorder was prescribed fluvoxamine 50 mg day(-1) in addition to clorazepate dipotassium and sulpiride. Depression was not improved and she complained of fatigue, lack of energy and drowsiness. These symptoms worsened within a few days of an increase in the dose of fluvoxamine to 50 mg twice daily. Since an interaction between fluvoxamine and tizanidine, prescribed by another clinic, was suspected, fluvoxamine was replaced with milnacipran 50 mg day(-1). Although her drowsiness improved, she complained of piloerection throughout her body. This symptom gradually abated within a week and when the dosage of milnacipran was increased to 100 mg day(-1) at 2 months, no further piloerection occurred. We calculated the changes in alpha(1)-adrenoceptor occupancy by endogenous norepinephrine during treatment with the usual doses of milnacipran, fluvoxamine and imipramine by using pharmacokinetic and pharmacodynamic parameters obtained from the literature.

RESULTS

The ratios of alpha(1)-adrenoceptor occupancy by endogenous norepinephrine during the treatment with milnacipran, fluvoxamine and imipramine to that without drug were estimated to be 7.13, 1.00 and 4.12, respectively. The alpha(1)-adrenoceptor occupancy by endogenous norepinephrine was increased in a dose-dependent manner by milnacipran, whereas fluvoxamine had essentially no effect.

CONCLUSIONS

The piloerection observed after the replacement of fluvoxamine with milnacipran in this patient appears to have been due to an increase in the alpha(1)-adrenoceptor occupancy by endogenous norepinephrine induced by milnacipran.

Stimulation of catecholamine synthesis via activation of p44/42 MAPK in cultured bovine adrenal medullary cells by milnacipran

Milnacipran is a serotonin noradrenaline reuptake inhibitor (SNRI) and is used clinically as an antidepressant. We report here the effect of milnacipran on catecholamine synthesis in cultured bovine adrenal medullary cells. Incubation of adrenal medullary cells with milnacipran (300 ng/ml, 1,065 nM) for 20 min resulted in a significant increase in 14C-catecholamine synthesis from [14C]tyrosine, but not from [14C]DOPA, whereas the selective serotonin reuptake inhibitors (SSRIs), paroxetine (300 ng/ml, 800 nM) and fluvoxamine (300 ng/ml, 691 nM), had little effect. Milnacipran, but not paroxetine or fluvoxamine, increased the activity of tyrosine hydroxylase, the rate-limiting step of catecholamine biosynthesis, in a concentration-dependent manner (100-300 ng/ml, 355-1,065 nM). U0126 (1 microM), an inhibitor of p44/42 mitogen-activated protein kinase (MAPK) kinase, abolished the stimulatory effects of milnacipran on tyrosine hydroxylase activity. Furthermore, incubation of cells with milnacipran (30-100 ng/ml) for 5 min activated p44/42 MAPK, whereas paroxetine and fluvoxamine did not. The present findings suggest that milnacipran activates tyrosine hydroxylase and then stimulates catecholamine synthesis through a p44/42 MAPK-dependent pathway in cultured bovine adrenal medullary cells.

Lack of pharmacokinetic interaction when switching from fluoxetine to milnacipran

The lack of a therapeutic effect or unsupportable side-effects can lead to substitution of one antidepressant by another. The present study investigated potential modifications to the pharmacokinetic profile of milnacipran at steady-state when it is substituted for fluoxetine without any washout period. The open-label, multiple dose, three-period study was carried out in 12 evaluable healthy volunteers. A reference period (period 1) comprising a 3.5-day treatment with milnacipran at 50 mg b.i.d. was followed, after a 5-10-day washout, by 3 weeks of administration of 20 mg fluoxetine once daily (period 2), immediately followed by a further 3.5 days of administration of milnacipran at 50 mg b.i.d. (period 3). Blood samples collected at each period were analysed for milnacipran, N-dealkyl milnacipran, fluoxetine and norfluoxetine. Potential drug-drug interactions were evaluated by comparing milnacipran pharmacokinetic parameters between periods 1 and 3. A steady-state of fluoxetine and its metabolite was effectively reached by the end of the 3-week period. A steady-state of milnacipran was reached on day 2 of both periods 1 and 3. Trough concentrations of milnacipran were 66 and 65 ng/ml before and after the fluoxetine administration period, respectively. Cmax values were 226 and 248 ng/ml. When comparing the kinetic parameters of milnacipran before and after fluoxetine treatment, all the 90% confidence intervals were in the 20% range. No significant difference in the adverse events of milnacipran was observed before or after fluoxetine administration.

Dual serotonin and noradrenaline reuptake inhibitors: Focus on their differences

There are three non-tricyclic dual serotonin (5-HT) and noradrenaline (NA) reuptake inhibitors (SNRIs) currently used in human therapeutics for psychiatric disorders. These medications differ in their in vitro potency to inhibit 5-HT and NA reuptake with differential ratios of activity. Using in vivo studies carried out in laboratory animals, which better reflect human physiology than experiments using lysed tissue in a test tube, venlafaxine is about three times more potent on 5-HT than NA reuptake, duloxetine five times, and milnacipran is about twice more potent on NA than 5-HT reuptake. Sustained administration of SNRIs induces different adaptive effects on presynaptic 5-HT and NA receptors controlling the function of 5-HT and NA neurons, suggesting that they may differentially affect transmission of these two neuronal systems. In the treatment of depression, SNRIs appear to have similar effectiveness and when compared to selective 5-HT reuptake inhibitors, they generally exert a superior antidepressant effect. Taken together, these observations suggest that individual patients not responding to a SNRI may present a favourable response to another agent within that family. SNRIs have different pharmacokinetic properties and exert distinct effects on the activity of liver metabolic enzymes. These features of SNRIs can help clinicians tailor treatment to individual patients.

SNRIs: their pharmacology, clinical efficacy, and tolerability in comparison with other classes of antidepressants

The class of serotonin and norepinephrine reuptake inhibitors (SNRIs) now comprises three medications: venlafaxine, milnacipran, and duloxetine. These drugs block the reuptake of both serotonin (5-HT) and norepinephrine with differing selectivity. Whereas milnacipran blocks 5-HT and norepinephrine reuptake with equal affinity, duloxetine has a 10-fold selectivity for 5-HT and venlafaxine a 30-fold selectivity for 5-HT. All three SNRIs are efficacious in treating a variety of anxiety disorders. There is no evidence for major differences between SNRIs and SSRIs in their efficacy in treating anxiety disorders. In contrast to SSRIs, which are generally ineffective in treating chronic pain, all three SNRIs seem to be helpful in relieving chronic pain associated with and independent of depression. Tolerability of an SNRI at therapeutic doses varies within the class. Although no direct comparative data are available, venlafaxine seems to be the least well-tolerated, combining serotonergic adverse effects (nausea, sexual dysfunction, withdrawal problems) with a dose-dependent cardiovascular phenomenon, principally hypertension. Duloxetine and milnacipran appear better tolerated and essentially devoid of cardiovascular toxicity.

A comparative study of milnacipran and paroxetine in outpatients with major depression

BACKGROUND

Milnacipran is a dual-action antidepressant which inhibits both serotonin and noradrenaline reuptake with no affinity for any neurotransmitter receptor studied.

METHODS

A 6-week double-blind multicentre study compared milnacipran (100 mg/day) with paroxetine (20 mg/day) in 300 outpatients with major depression. Efficacy was evaluated using HAMD17, MADRS and CGI for severity of illness and global improvement. Data were analysed on an intention to treat, last observation carried forward, basis.

RESULTS

Milnacipran and paroxetine were both effective and well tolerated with no significant difference in their effects. After treatment discontinuation, milnacipran was associated with significantly less emergent symptoms. Responders, at endpoint, to milnacipran had significantly greater levels of psychomotor retardation at baseline than non-responders.

LIMITATIONS

The study did not include a placebo group so that it is impossible to determine absolute levels of efficacy.

CONCLUSIONS

Both milnacipran and paroxetine were effective and well tolerated by outpatients with major depression treated for 6 weeks. After treatment discontinuation milnacipran was associated with less emergent symptoms. Psychomotor retardation at baseline may be a predictive factor of a favourable response to milnacipran.

A comparative study of milnacipran and imipramine in the treatment of major depressive disorder

The antidepressant efficacy and safety of milnacipran, a dual action antidepressant drug which inhibits the reuptake of serotonin and noradrenaline, was compared with that of the tricyclic antidepressant, imipramine, in a multi-centre, double-blind, randomised, parallel group, comparative trial in 5 hospital centres in Spain. One hundred patients hospitalised with a diagnosis of major depressive disorder according to the Diagnostic and Statistical Manual of the American Psychiatry Association (third revision), with a minimum score of 25 on the Montgomery and Asberg Depression Rating Scale were treated for 6 weeks with milnacipran (100 mg/day) or imipramine (150 mg/day). Both treatments showed similar efficacy in reducing depressive symptoms. The frequency of most adverse events in the milnacipran-treated patients was lower than that observed in the imipramine group, particularly those related to anticholinergic symptoms. Dysuria and shivering, however, were more common with milnacipran. The results of this study support others which have demonstrated that milnacipran has equivalent efficacy but superior tolerability to a tricyclic antidepressant such as imipramine.

Quality assessment of meta-analyses of RCTs of pharmacotherapy in major depressive disorder

BACKGROUND

Meta-analyses (MAs) of randomized controlled trials (RCTs) have the potential to provide the highest level of evidence, but the quality of published MAs has not been systematically assessed. Therefore, we determined reliability was significant (kappa = 0.89; p < 0.05). the quality of reporting in MAs of RCTs of pharmacotherapy for major depressive disorder (MDD) in adults (18-65 years) without comorbidities and examine trends over time.

METHODS

MEDLINE, EMBASE, Healthstar, Psychlit and Cochrane databases were searched (1980-2002) by 4 independent reviewers for MAs of RCTs. Articles meeting inclusion criteria were blinded. Inter-rater reliability (kappa) was evaluated using a test-retest strategy on 4 articles. Quality was (p = 0.74) did not detect a difference in quality of assessed using the QUOROM checklist. Time trends were evaluated by calculating Spearman's rho.

RESULTS

One hundred articles were identified, 68 were excluded [co-morbidities (9), inappropriate comparator (13), inappropriate outcome (15), article not available (5), inappropriate patient population (15), and inappropriate study design (11)]; 32 were included. Initial kappa was 0.81 (p < 0.05). After resolution of disagreements, the test-retest The mean overall quality score was 50.2% (SD 15.8%, range = 16.7-88.9%). The overall score for Titles was very poor (22%), Abstracts (40%) and Methods (49%) were poor, while overall Results score was minimally acceptable (54%). Good quality scores were found for Introduction (91%) and Discussion (97%). No time trends were identified using Spearman's correlation analysis (rho 0.05; p = 0.79). The Mann-Whitney U test articles published before and after the QUOROM.

CONCLUSION

Despite quality guidelines, the average quality of published MAs of antidepressants is barely acceptable (50.2%). A need exists for adherence to standardized reporting and quality guidelines.

Effects of milnacipran on driving vigilance

BACKGROUND Many psychotropic drugs modify sensory and/or psychomotor functions involved in car driving and as such they can be a causative factor in road accidents. AIM To investigate the effects of the administration of milnacipran, a serotonin and noradrenaline dual-action antidepressant, on the sensory and psychomotor skills implicated in car driving and to determine any possible interactions with the effect of alcohol. METHODS Double-blind, placebo-controlled four-sequence cross-over design with 12 healthy volunteers. Laboratory tests designed to explore motor responses to auditory and visual stimuli and equilibrium on a sensory platform, as well as tests in a real on-road car driving situation, were carried out before the drug administration (control) and at the end of each sequence. RESULTS There was no significant difference in the results of laboratory tests between groups receiving milnacipran compared to placebo. In a real driving situation there were no significant effects of milnacipran. In addition, milnacipran did not accentuate the negative effects of alcohol. CONCLUSIONS Milnacipran, administered at 50 mg b.i.d. to healthy volunteers, does not modify the psychomotor skills required for driving.

Milnacipran plasma levels and antidepressant response in Japanese major depressive patients

The relationship between antidepressant effects and plasma levels of milnacipran was studied in 49 cases of major depression without psychotic features during 6 weeks of milnacipran treatment. The daily dose of milnacipran was 50 mg/day for the first week, and up to 100 mg/day thereafter. Depressive symptoms were evaluated by the Montgomery and Asberg depression rating scale (MADRS) before treatment and at 1, 2, 4 and 6 weeks after the beginning of this study. Thirty-four patients (69.4%) were responders (defined as a 50% or greater decrease in the baseline MADRS score). Significant differences of MADRS scores were seen from 1 week after the beginning of this study (p=0.004, unpaired t-test) between responders and nonresponders. The mean plasma milnacipran level of responders, 82.0 +/- 29.4 ng/ml, was similar to that of non-responders, 78.6+/-23.1 ng/ml; there was no significant difference between responders and nonresponders. Neither a significant linear nor a curvilinear relationship was obtained between the final MADRS score and the plasma levels of milnacipran. Although there was no significant relationship between the plasma levels of milnacipran and the antidepressant response, milnacipran should be considered an efficacious agent in the treatment of major depressive patients.

Dual action antidepressants and some important considerations

OBJECTIVE

To review controlled studies of long-term treatment and their side-effects with newer dual action antidepressants following an acute episode of major depression.

METHOD

A literature review (MedLine) was undertaken and references were selected for their relevance and methodology in describing their contribution to the examination of our objective.

RESULT AND CONCLUSION

Three dual action antidepressants are identified: venlafaxine, mirtazapine and milnacipran. These are more effective and better tolerated than the older tricyclic antidepressants in the treatment of an acute episode of depression and in the prevention of relapse. They also offer advantages in that they lack autonomic side-effects of the tricyclics. However, sedation, nausea and sexual side-effects may occur with venlafaxine, and weight gain with mirtazapine.

Milnacipran in the treatment of bulimia nervosa: a report of 16 cases

Controlled trials in patients with bulimia nervosa have demonstrated efficacy of antidepressant medications with serotonergic function (e.g. fluoxetine) as well as noradrenergic function (e.g. desipramine). Sixteen out-patients with bulimia nervosa according to DSM-IV criteria were treated in a drug surveillance with 100 mg of milnacipran, a specific serotonin and noradrenaline reuptake inhibitor (SNRI). Ten patients completed the 8-week observation period. The reasons for premature attrition were improvement in one patient (no. 12), a generalized exanthema in one patient (no. 7), severe nausea in one patient (no. 8) and non-compliance due to non-drug-related reasons in three patients (no. 1, 2, and 16). An intent-to-treat analysis exhibited a significant reduction in weekly binge eating and vomiting frequency from baseline to the end of treatment. Three patients stopped binge eating and purging completely during the last week of treatment. Furthermore, there was a concomitant decrease of depression ratings (HAMD, BDI). Our preliminary data give rise to the notion that milnacipran may be promising in the treatment of bulimia nervosa.

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.

Evidence-based prescribing of antidepressants

Modern antidepressants are required to undergo extensive clinical investigation before their commercialisation is authorised, and this provides the basis for the "evidence-based recommendations" for their use. Because of the rigorous methodology required in formal clinical trials in order to establish efficacy, the population studied and the conditions of use of a treatment are likely to differ substantially from those encountered in everyday clinical practice. There is limited opportunity in clinical trials for casual observation of the effects of the drug, its efficacy in patients with co-morbid disorders, or its use outside of the strict indication for which the compound seeks a licence. The observations, case studies, open trials and small comparative trials that are conducted on an antidepressant after it has been launched can provide important information. The less rigorous methodology is to some extent compensated by their relevance to everyday prescribing and their openness to chance discoveries. They can provide complementary information on responder characteristics and acceptance of side effects and can suggest potential conditions and indications not originally foreseen. This body of data can be referred to as "prescribing-based evidence". The obvious complementarity of these two bodies of information is illustrated by reference to the serotonin and noradrenaline reuptake inhibitor (SNRI), milnacipran, which has been the subject of intense post-marketing study, especially in Japan. The newly discovered efficacy of milnacipran in chronic pain, both associated with depression and in conditions such as fibromyalgia, is an example of the extended understanding that can be obtained by such studies.

Antidepressants, old and new. A review of their adverse effects and toxicity in overdose

The newer antidepressants are as efficacious as the older agents in the treatment of depression. They have a side effect profile that is different from the older drugs and are generally better tolerated. Drug-drug interactions do exist with some of these agents and can usually be predicted from knowledge of their metabolism. When taken in overdose as the sole agents they are rarely fatal; seizures, nausea, vomiting, decreased level of consciousness, and tachycardia are common. In combination with other drugs, toxicity can be more severe. The serotonin syndrome can occur with many of these drugs, and the emergency physician must be vigilant in the evaluation of the overdose patient. CAs and older MAOIs are still in use and remain dangerous when taken in overdose. Patients asymptomatic after a period of observation in the ED usually can be discharged after psychiatric evaluation, when it is required.

Milnacipran: an antidepressant with dual selectivity of action on noradrenaline and serotonin uptake

Milnacipran is a new antidepressant which possesses potent and doubly selective action in that it inhibits both the re-uptake of serotonin and noradrenaline without any effect on other neurotransmitter systems. The almost equipotent inhibition of serotonin and noradrenaline by milnacipran is functionally reflected in the several-fold and long-lasting increase of the levels of these monoamines in the brain and in antidepressant-like effects in animals. In man, milnacipran distinguishes itself from many other antidepressants by its simple pharmacokinetics. It shows linear dose-concentration relationship over a dose range of 25-200 mg/day. It is rapidly and extensively absorbed and almost completely eliminated after 12 h (t1/2 approx. 8 h). Steady-state plasma levels are reached within 32-48 h after twice daily oral administration. Milnacipran is highly bioavailable (>85 per cent) and its metabolism does not involve the cytochrome P450 enzyme system. In clinical studies, milnacipran showed antidepressant efficacy similar to that of TCAs and SSRIs and superior to that of placebo. At the optimum dose of 100 mg/day, after 4-8 weeks of treatment, 60-64 per cent of in- or out-patients with major depression improve (>/=50 per cent reduction of HAMD and MADRS score) and about 32-39 per cent of them achieve full remission (HAMD score</=7). Milnacipran has proved to be a very safe drug with a benign adverse event profile clearly superior to that of TCAs and, to a certain extent, that of SSRIs. Only about 10 per cent of patients experience side-effects and only dysuria occurred more frequently (2 per cent) with milnacipran than with TCAs or SSRIs. Milnacipran appears therefore to be an antidepressant with a very favourable benefit/risk ratio. Copyright 2000 John Wiley & Sons, Ltd.

Pharmacodynamics of milnacipran in young and elderly volunteers

AIMS

To investigate the pharmacodynamics of milnacipran in healthy young and elderly volunteers.

METHODS

Randomized double-blind crossover designs were employed and a standardized psychometric battery was administered pre and post dose for both studies. In the first study 10 healthy young volunteers received milnacipran 12.5 mg, 25 mg, 50 mg, 100 mg as a single dose or matched placebo. The test battery was administered at baseline and at 1, 2, 4 and 6 h post dose. The second study compared the effects of milnacipran 75 mg (50 mg+25 mg) per day, amitriptyline 50 mg (25 mg+25 mg) per day and placebo for 3 days' dosing in healthy volunteers aged over 65 years. The test battery was administered at baseline and at 2, 10 and 24 h post dose. The psychometric battery included critical flicker fusion (CFF), choice reaction time (CRT), compensatory tracking (CTT) and tests of short-term memory (STM), subjective sedation (LARS) and subjective sleep (LSEQ).

RESULTS

Milnacipran produced no significant dose related effects in the young volunteers. For the elderly, milnacipran significantly (P<0.05) raised CFF scores compared with placebo but had no significant effects on any of the other measures used. Amitriptyline, in contrast, significantly (P<0. 05) lowered CFF threshold, lengthened CRT and increased error on the CTT. On the subjective variables, LARS and LSEQ, amitriptyline increased ratings both of sedation and of difficulty in waking from sleep.

CONCLUSIONS

The results showed that milnacipran at single doses of up to 100 mg in healthy young volunteers is free from disruptive effects on cognitive function and psychomotor performance. In addition, milnacipran 75 mg (50+25 mg) appears to be free of negative effects on cognitive function in elderly volunteers, where it seemingly improves performance on CFF. In contrast, the tricyclic antidepressant amitriptyline, used here as a positive internal control, significantly impaired performance in the elderly on the majority of psychometric measures used in this study. This finding not only validated the sensitivity of this current test battery but also indicates the potential behavioural toxicity of amitriptyline in clinical use in the elderly.

Recent advances in antidepressant drug therapy

Many new antidepressants are available for use. The acute effects of administration are mainly manifested as side-effects, whereas the chronic effects take 2-3 weeks to set in and are responsible for therapeutic action. Such changes may include formation and release of neurotransmitters, changes in pre-synaptic uptake, and changes in receptor density and sensitivity. The noradrenergic and serotonergic systems are not separate, but are entwined with each other. The newer SSRI citalopram, and drugs from the SNRI, NaSSA and NAN classes, have been shown in controlled trials to be equivalent to, or more efficacious than, TCAs and/or SSRIs. They have an improved side-effect profile, especially when compared to TCAs, and hence are better tolerated.

Design and synthesis of new potent, silent 5-HT1A antagonists by covalent coupling of aminopropanol derivatives with selective serotonin reuptake inhibitors

Hybrid molecules built up by covalent coupling of aminopropanol derivatives (especially pindolol) with antidepressant drugs like fluoxetine, paroxetine or milnacipran were found to be potent and silent 5-HT1A antagonists (KB < 1 nM for 7c and 9a).

Long-term efficacy and safety of milnacipran compared to clomipramine in patients with major depression

Milnacipran is a new antidepressive drug, a combined noradrenaline/serotonin (NA/5-HT) reuptake inhibitor, which has been suggested to be as effective as and better tolerated than tricyclic antidepressants. Since long-term studies are lacking, we compared the efficacy, safety and tolerability of milnacipran and clomipramine in a double-blind, randomized, parallel-group study setting during 26 weeks of treatment in patients with major depression. A total of 107 patients were treated with either milnacipran (n=52) or clomipramine (n=55). Due to active treatment of duration less than 12 days in four patients and protocol deviation in one patient, in total 47 milnacipran-treated patients were eligible for efficacy analysis. Nine patients in the clomipramine group continued on active treatment for less than 12 days. Thus 46 clomipramine-treated patients were finally included in the efficacy analysis. After 1 week of dose escalation, there was a fixed dosage regimen of either milnacipran (200 mg daily) or clomipramine (150 mg daily) during weeks 2 to 10, followed by flexible dosing of milnacipran (100, 150 or 200 mg daily) or clomipramine (75, 100 or 150 mg daily) during weeks 11 to 26. A total of 53 patients (49%) completed the 26-week study period; 21% (11/52) of the patients in the milnacipran group and 38% (21/55) of the patients in the clomipramine group discontinued their medication prematurely due to adverse events, whereas 19% (10/52) of those on milnacipran and 7% (4/55) of those on clomipramine treatment withdrew due to either lack of efficacy or clinical deterioration. The mean change (+/-SD) in the Hamilton Depression Rating Scale (HAMD) score between the baseline and the last rating ranged from 23.7+/-3.1 to 12.0+/-9.5 in the milnacipran-treated patients and from 23.1+/-3.5 to 8.0+/-8.5 in the clomipramine-treated patients, revealing a significant difference in favour of clomipramine. In total 58% of the milnacipran-treated patients vs. 72% of the clomipramine-treated patients showed a > or = 50% reduction in their baseline HAMD scores and 45% vs. 63% had an HAMD score of < or = 7 at the last rating, respectively. Moreover, the time to the onset of the antidepressant action (defined as > or = 50% reduction of the baseline HAMD score) showed a significant difference in favour of clomipramine. In addition, clomipramine was significantly more efficacious in patients with a baseline HAMD score of > or = 24 as evidenced by the analysis of the HAMD score at week 6 and at the last rating. The Montgomery Asberg Depression Rating Scale (MADRS) and the Clinical Global Impression (CGI) scale did not show significant differences between the treatment groups. The safety analysis did not reveal any differences of clinical significance in cardiovascular variables between the study drugs. Dry mouth was significantly less frequently reported by the milnacipran-treated patients during the early and later phases (weeks 6 to 26) of the study, while insomnia was more common in the milnacipran group during weeks 1 to 6. In conclusion, milnacipran appeared to be less effective than clomipramine in the long-term treatment of depression. The side-effects of the drugs differed to a certain extent, and milnacipran tended to be somewhat better tolerated than clomipramine.