Lack of Interaction of Milnacipran with the Cytochrome P450 Isoenzymes Frequently Involved in the Metabolism of Antidepressants

Milnacipran and Vanillin Alleviate Fibromyalgia-Associated Depression in Reserpine-Induced Rat Model: Role of Wnt/β-Catenin Signaling

Fibromyalgia (FM) patients are highly susceptible to depression. Wnt/β-catenin signaling has shown a crucial role against depression in several studies. The FDA-approved FM drug, milnacipran (Miln), has shown antinociceptive potential against FM. Yet, no study has investigated its antidepressant potential in FM. Vanillin (Van), a well-known phytochemical often employed as flavoring agent, has been previously reported for its antidepressant and antinociceptive effects in several animal models, but has not been tested so far in FM. This study explored the antidepressant effect of Van and Miln in FM through investigating Wnt/β-catenin signaling. FM was induced in female Wistar rats by injecting reserpine (1 mg/kg/day s.c) for 3 days. Thereafter, animals received either Miln (30 mg/kg/day p.o) or Van (100 mg/kg/day p.o) for the subsequent 14 days. Results showed that both drugs demonstrated antidepressant effect in forced swimming test besides analgesic, and antiallodynic influences observed in Randall-Selitto, hot plate, cold allodynia, Von-Frey, and tail immersion tests. Biochemically, Miln and Van significantly enhanced serotonergic transmission in the hippocampus and upregulated the protein expression of the Wnt/GSK-3β/β-catenin signaling axis, including the downstream proteins, T cell factor, and dicer. This is followed by subsequent upregulation of the resilience micro ribonucleic acids (miRNAs) 124 and 135. Histopathological examinations corroborated the biochemical and molecular findings. Interestingly, these effects of Miln and Van were overturned via administration of the β-catenin inhibitor, XAV939 (0.1 mg/kg, i.p., daily). In conclusion, this study outlined the antidepressant aptitude of Miln and Van through activating Wnt/β-catenin signaling in the hippocampus in reserpine-induced FM.

Systemic and Brain Pharmacokinetics of Milnacipran in Mice: Comparison of Intraperitoneal and Intravenous Administration

Milnacipran is a dual serotonin and norepinephrine reuptake inhibitor, clinically used for the treatment of major depression or fibromyalgia. Currently, there are no studies reporting the pharmacokinetics (PK) of milnacipran after intraperitoneal (IP) injection, despite this being the primary administration route in numerous experimental studies using the drug. Therefore, the present study was designed to investigate the PK profile of IP-administered milnacipran in mice and compare it to the intravenous (IV) route. First a liquid chromatography-mass spectrometry (LC-MS/MS) method was developed and validated to accurately quantify milnacipran in biological samples. The method was used to quantify milnacipran in blood and brain samples collected at various time-points post-administration. Non-compartmental and PK analyses were employed to determine key PK parameters. The maximum concentration (Cmax) of the drug in plasma was at 5 min after IP administration, whereas in the brain, it was at 60 min for both routes of administration. Curiously, the majority of PK parameters were similar irrespective of the administration route, and the bioavailability was 92.5% after the IP injection. These findings provide insight into milnacipran's absorption, distribution, and elimination characteristics in mice after IP administration for the first time and should be valuable for future pharmacological studies.

Milnacipran for the Treatment of Fibromyalgia

Purpose of review

This is a comprehensive review of the literature regarding the use of milnacipran in treating fibromyalgia. A chronic pain disorder with other system disturbances, fibromyalgia is often resistant to many therapeutic approaches. This review presents the background, evidence, and indications for using milnacipran as a treatment option for this condition.

Recent Findings

The definition of fibromyalgia has evolved over many years as it is a relatively tricky syndrome to measure objectively. Today, it is characterized by chronic, widespread pain accompanied by alterations in sleep, mood, and other behavioral aspects. A variety of therapeutic regimens currently used to treat the syndrome as a singular approach are rarely effective.Milnacipran is one of three drugs currently approved by the FDA for the treatment of fibromyalgia. It acts as a serotonin and norepinephrine reuptake inhibitor, which results in decreased pain transmission. Milnacipran remains an effective treatment option for fibromyalgia in adults and needs to be further evaluated with existing therapeutic approaches.

Summary

Fibromyalgia is a broad-spectrum disorder primarily characterized by chronic pain coupled with disturbances in cognitive functioning and sleep. The progression of this syndrome is often debilitating and significantly affects the quality of life. Milnacipran is one of three FDA-approved drugs used to alleviate the symptom burden and is comparatively more therapeutic in specific domains of fibromyalgia. A more holistic approach is needed to treat fibromyalgia effectively and further research, including direct comparison studies, should be conducted to fully evaluate the usefulness of this drug.

Tools for optimising pharmacotherapy in psychiatry (therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests): focus on antidepressants

Objectives: More than 40 drugs are available to treat affective disorders. Individual selection of the optimal drug and dose is required to attain the highest possible efficacy and acceptable tolerability for every patient.Methods: This review, which includes more than 500 articles selected by 30 experts, combines relevant knowledge on studies investigating the pharmacokinetics, pharmacodynamics and pharmacogenetics of 33 antidepressant drugs and of 4 drugs approved for augmentation in cases of insufficient response to antidepressant monotherapy. Such studies typically measure drug concentrations in blood (i.e. therapeutic drug monitoring) and genotype relevant genetic polymorphisms of enzymes, transporters or receptors involved in drug metabolism or mechanism of action. Imaging studies, primarily positron emission tomography that relates drug concentrations in blood and radioligand binding, are considered to quantify target structure occupancy by the antidepressant drugs in vivo. Results: Evidence is given that in vivo imaging, therapeutic drug monitoring and genotyping and/or phenotyping of drug metabolising enzymes should be an integral part in the development of any new antidepressant drug.Conclusions: To guide antidepressant drug therapy in everyday practice, there are multiple indications such as uncertain adherence, polypharmacy, nonresponse and/or adverse reactions under therapeutically recommended doses, where therapeutic drug monitoring and cytochrome P450 genotyping and/or phenotyping should be applied as valid tools of precision medicine.

Therapy response prediction in major depressive disorder: current and novel genomic markers influencing pharmacokinetics and pharmacodynamics

Major depressive disorder is connected with high rates of functional disability and mortality. About a third of the patients are at risk of therapy failure. Several pharmacogenetic markers especially located in CYP450 genes such as CYP2D6 or CYP2C19 are of relevance for therapy outcome prediction in major depressive disorder but a further optimization of predictive tools is warranted. The article summarizes the current knowledge on pharmacogenetic variants, therapy effects and side effects of important antidepressive therapeutics, and sheds light on new methodological approaches for therapy response estimation based on genetic markers with relevance for pharmacokinetics, pharmacodynamics and disease pathology identified in genome-wide association study analyses, highlighting polygenic risk score analysis as a tool for further optimization of individualized therapy outcome prediction.

Interactions between Antidepressants and Warfarin: A Review

Background:

Since warfarin has a very narrow therapeutic index, the interaction between warfarin and antidepressants is very critical and has potentially severe consequences. It is unclear whether clinicians have sufficient knowledge about the risk of bleeding when warfarin and antidepressants are used concomitantly.

Objective:

In this systematic review, we discuss the main considerations when using warfarin with antidepressants.

Methods:

The information about warfarin-antidepressant interactions was obtained from Google Scholar®, PubMed/MEDLINE® and a hand search of the published literature. The following research terms which were systematically combined with each other to find articles: warfarin, anticoagulant, interactions, antidepressant (and each antidepressant name individually), SSRI, SNRI, TCA, MAOI.

Results:

Several possible mechanisms that can cause bleeding when antidepressants and warfarin are used concomitantly, have been discussed. According to the available data, sertraline and citalopram/ escitalopram are safer antidepressants to use with warfarin, whereas fluoxetine and fluvoxamine have a higher interaction potential with warfarin. The remaining antidepressants appear to lie somewhere in between and have little empirical data to guide the clinicians.

Conclusion:

It is recommended that when an antidepressant is prescribed to a patient using warfarin, patient’s international normalized ratio (INR) level should be checked regularly. In this review, the interaction between warfarin and antidepressants, including new ones, were evaluated inclusively and in detail.

Clinically significant drug interactions with newer antidepressants

After the introduction of selective serotonin reuptake inhibitors (SSRIs), other newer antidepressants with different mechanisms of action have been introduced in clinical practice. Because antidepressants are commonly prescribed in combination with other medications used to treat co-morbid psychiatric or somatic disorders, they are likely to be involved in clinically significant drug interactions. This review examines the drug interaction profiles of the following newer antidepressants: escitalopram, venlafaxine, desvenlafaxine, duloxetine, milnacipran, mirtazapine, reboxetine, bupropion, agomelatine and vilazodone. In general, by virtue of a more selective mechanism of action and receptor profile, newer antidepressants carry a relatively low risk for pharmacodynamic drug interactions, at least as compared with first-generation antidepressants, i.e. monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants (TCAs). On the other hand, they are susceptible to pharmacokinetic drug interactions. All new antidepressants are extensively metabolized in the liver by cytochrome P450 (CYP) isoenzymes, and therefore may be the target of metabolically based drug interactions. Concomitant administration of inhibitors or inducers of the CYP isoenzymes involved in the biotransformation of specific antidepressants may cause changes in their plasma concentrations. However, due to their relatively wide margin of safety, the consequences of such kinetic modifications are usually not clinically relevant. Conversely, some newer antidepressants may cause pharmacokinetic interactions through their ability to inhibit specific CYPs. With regard to this, duloxetine and bupropion are moderate inhibitors of CYP2D6. Therefore, potentially harmful drug interactions may occur when they are coadministered with substrates of these isoforms, especially compounds with a narrow therapeutic index. The other new antidepressants are only weak inhibitors or are not inhibitors of CYP isoforms at usual therapeutic concentrations and are not expected to affect the disposition of concomitantly administered medications. Although drug interactions with newer antidepressants are potentially, but rarely, clinically significant, the use of antidepressants with a more favourable drug interaction profile is advisable. Knowledge of the interaction potential of individual antidepressants is essential for safe prescribing and may help clinicians to predict and eventually avoid certain drug combinations.

Drug interaction in psycho-oncology: antidepressants and antineoplastics

BACKGROUND AND OBJECTIVES

Although there is a growing impact of psychiatric and depressive disorders in cancer patients, literature on the idiosyncrasies of antidepressants (ADs) used in those conditions and their interactions with antineoplastic agents (ANs) is scarce. Sharing the same biotransformation pathways enhances the risk of drug interaction between ADs and ANs, specifically when compounds are inducers, inhibitors or substrates of cytochrome P450 (CYP 450). In cancer patients, such drug interactions may result in less efficacy of the drug and/or increase of their side effects. Therefore, the choice of AD should be cautious (safe and effective) and well supported. The main purpose of this review was to analyze the individual pharmacokinetic properties of the most used ADs and ANs in order to summarize the risk of possible drug interactions between them, anticipating the consequences of their coadministration.

METHODS

The authors reviewed books and PubMed online articles published in the last 6 years.

RESULTS

Most of the ANs are subject to transformation by CYP 450 3A4 and their coadministration with ADs, that have inhibitory properties of this CYP isoform, such as fluoxetine, sertraline, paroxetine and fluvoxamine, may result in the loss of the AN's efficacy or higher toxicity.

CONCLUSION

Among the ADs, escitalopram, citalopram, venlafaxine, mirtazapine and milnacipran stand out for their weak CYP 450 inhibitory potential and their safety profile in those patients.

Getting the balance right: Established and emerging therapies for major depressive disorders

Major depressive disorder (MDD) is a common and serious illness of our times, associated with monoamine deficiency in the brain. Moreover, increased levels of cortisol, possibly caused by stress, may be related to depression. In the treatment of MDD, the use of older antidepressants such as monoamine oxidase inhibitors and tricyclic antidepressants is decreasing rapidly, mainly due to their adverse effect profiles. In contrast, the use of serotonin reuptake inhibitors and newer antidepressants, which have dual modes of action such as inhibition of the serotonin and noradrenaline or dopamine reuptake, is increasing. Novel antidepressants have additive modes of action such as agomelatine, a potent agonist of melatonin receptors. Drugs in development for treatment of MDD include triple reuptake inhibitors, dual-acting serotonin reuptake inhibitors and histamine antagonists, and many more. Newer antidepressants have similar efficacy and in general good tolerability profiles. Nevertheless, compliance with treatment for MDD is poor and may contribute to treatment failure. Despite the broad spectrum of available antidepressants, there are still at least 30% of depressive patients who do not benefit from treatment. Therefore, new approaches in drug development are necessary and, according to current research developments, the future of antidepressant treatment may be promising.

Milnacipran: a selective serotonin and norepinephrine dual reuptake inhibitor for the management of fibromyalgia

Milnacipran, a serotonin and norepinephrfrine reuptake inhibitor with preferential inhibition of norepinephrine reuptake over serotonin, is approved in the United States for the management of fibromyalgia. Owing to its effects on norepinephrine and serotonin, as well as its lack of activity at other receptor systems, it was hypothesized that milnacipran would provide improvements in pain and other fibromyalgia symptoms without some of the unpleasant side effects associated with other medications historically used for treating fibromyalgia. The clinical safety and efficacy of milnacipran 100 and 200 mg/day in individuals with fibromyalgia has been investigated in four large, randomized, double-blind, placebo-controlled studies and three long-term extension studies. The clinical studies used composite responder analyses to identify the proportion of individual patients reporting simultaneous and clinically significant improvements in pain, global status, and physical function, in addition to assessing improvement in various symptom domains such as fatigue and dyscognition. In the clinical studies, patients receiving milnacipran reported significant improvements in pain and other symptoms for up to 15 months of treatment. Most adverse events were mild to moderate in severity and were related to the intrinsic pharmacologic properties of the drug. Long-term exposure to milnacipran did not result in any new safety concerns. As with other serotonin and norepinephrine reuptake inhibitors, increases in heart rate and blood pressure have been observed in some patients with milnacipran treatment.

New and emerging therapeutic agents for the treatment of fibromyalgia: an update

Fibromyalgia (FM) is a chronic widespread pain condition that is estimated to affect 5 million US adults. Several molecular pathophysiologies are thought to contribute to the symptoms of FM, complicating the development of effective clinical management techniques. It is now known that abnormalities in both nociceptive and central pain processing systems are necessary (but perhaps not sufficient) to condition the onset and maintenance of FM, producing associated neuropsychologic symptoms such as pronounced fatigue, sleep abnormalities, cognitive difficulties, stress sensitivity, anxiety, and depression. Current treatment strategies are focused primarily on correcting the pathophysiologic mechanisms underlying these nervous system abnormalities. Clinical studies demonstrate the safety and efficacy of three drugs recently approved for the treatment of FM: pregabalin (an alpha-2-delta ligand), and duloxetine and milnacipran (serotonin/norepinephrine reuptake inhibitors). This review describes these pharmaceuticals in detail and discusses their current roles in FM management.

Role and rationale for the use of milnacipran in the management of fibromyalgia

Fibromyalgia (FM) is a complex syndrome characterized by chronic widespread musculoskeletal pain which is often accompanied by multiple other symptoms, including fatigue, sleep disturbances, decreased physical functioning, and dyscognition. Due to these multiple symptoms, as well as high rates of comorbidity with other related disorders, patients with FM often report a reduced quality of life. Although the pathophysiology of FM is not completely understood, patients with FM experience pain differently from the general population, most likely due to dysfunctional pain processing in the central nervous system leading to both hyperalgesia and allodynia. In many patients with FM, this aberrant pain processing, or central sensitization, appears to involve decreased pain inhibition within the spinal tract, which is mediated by descending pathways that utilize serotonin, norepinephrine, and other neurotransmitters. The reduced serotonin and norepinephrine levels observed in patients with FM suggest that medications which increase the levels of these neurotransmitters, such as serotonin and norepinephrine reuptake inhibitors (SNRIs), may have clinically beneficial effects in FM and other chronic pain conditions. Milnacipran is an SNRI that has been approved for the management of FM. In clinical trials, treatment with milnacipran for up to 1 year has been found to improve the pain and other symptoms of FM. Because FM is characterized by multiple symptoms that all contribute to the decreased quality of life and ability to function, the milnacipran pivotal trials implemented responder analyses. These utilized a single composite endpoint to identify the proportion of patients who reported simultaneous and clinically significant improvements in pain, global disease status, and physical function. Other domains assessed during the milnacipran trials include fatigue, multidimensional functioning, mood, sleep quality, and patient-reported dyscognition. This review article provides information intended to help clinicians make informed decisions about the use of milnacipran in the clinical management of patients with FM. It draws primarily on results from 2 of the pivotal clinical trials that formed the basis of approval of milnacipran in the United States by the Food and Drug Administration.

Milnacipran: A New Treatment for Fibromyalgia Syndrome

Objective:

To review the pharmacology, efficacy, and tolerability of milnacipran, a dual serotonin-norepinephrine reuptake inhibitor (SNRI), in the treatment of symptoms of fibromyalgia syndrome and associated fibromyalgia pain.

Data Sources:

English-language articles were obtained via searches of MEDLINE (1950-January 2010), EMBASE (1980-January 2010), and International Pharmaceutical Abstracts (1970-January 2010), using the key words milnacipran, fibromyalgia, serotonin-norepinephrine reuptake inhibitors, F 2207, and pain management. Bibliographies of selected articles were used to identify additional sources.

Study Selection and Data Extraction:

Available published articles reporting the results of human studies of milnacipran were reviewed for inclusion in this article. Additional information regarding pharmacology, adverse events, contraindications, and precautions was obtained from the manufacturer's prescribing information.

Data Synthesis:

Milnacipran is a dual SNRI approved for the treatment of fibromyalgia symptoms and pain. Milnacipran is well absorbed upon oral administration, has limited first-pass elimination, has a short halflife, and is not metabolized by the cytochrome P450 enzyme group. Phase 3 clinical trials evaluating the efficacy of milnacipran demonstrated a 10–20% higher composite response rate compared with placebo in the treatment of fibromyalgia symptoms and associated pain when milnacipran was given in doses of 100–200 mg/day. Significant improvements in physical functioning, fatigue, cognition, and mental health were also noted. Milnacipran appears to have fewer anticholinergic, sedative, and cardiovascular adverse effects compared with other pharmacologic treatments of fibromyalgia. Nausea was the most commonly reported adverse event.

Conclusions:

Milnacipran is an effective treatment for the symptoms of fibromyalgia syndrome and associated pain. Additional studies are needed to assess comparative effectiveness with that of other pharmacologic treatments of fibromyalgia syndrome, long-term efficacy, and safety.

Milnacipran for the management of fibromyalgia syndrome

Fibromyalgia syndrome (FMS) is a widespread pain condition associated with fatigue, cognitive dysfunction, sleep disturbance, depression, anxiety, and stiffness. Milnacipran is one of three medications currently approved by the Food and Drug Administration in the United States for the management of adult FMS patients. This review is the second in a three-part series reviewing each of the approved FMS drugs and serves as a primer on the use of milnacipran in FMS treatment including information on pharmacology, pharmacokinetics, safety and tolerability. Milnacipran is a mixed serotonin and norepinephrine reuptake inhibitor thought to improve FMS symptoms by increasing neurotransmitter levels in descending central nervous system inhibitory pathways. Milnacipran has proven efficacy in managing global FMS symptoms and pain as well as improving symptoms of fatigue and cognitive dysfunction without affecting sleep. Due to its antidepressant activity, milnacipran can also be beneficial to FMS patients with coexisting depression. However, side effects can limit milnacipran tolerability in FMS patients due to its association with headache, nausea, tachycardia, hyper- and hypotension, and increased risk for bleeding and suicidality in at-risk patients. Tolerability can be maximized by starting at low dose and slowly up-titrating if needed. As with all medications used in FMS management, milnacipran works best when used as part of an individualized treatment regimen that includes resistance and aerobic exercise, patient education and behavioral therapies.

Milnacipran: beyond a role of antidepressant

Milnacipran is a serotonin and norepinephrine reuptake inhibitor (SNRI) with negligible effects on any presynaptic or postsynaptic receptors. Milnacipran has unique pharmacokinetic and pharmacodynamic characteristics that distinguish it from the other marketed serotonin and norepinephrine reuptake inhibitors, venlafaxine, desvenlafaxine, and duloxetine such as equipotent serotonin and norepinephrine reuptake inhibition and a linear dose-concentration trend at therapeutic doses. The half-life of milnacipran is approximately 8 hours. In addition, milnacipran does not inhibit the cytochrome P 450 system, indicating minimal propensity for drug-drug interactions. The antidepressant efficacy of milnacipran has been clearly established in a number of randomized, double-blind, placebo-controlled clinical trials, and it has been widely used for treating major depressive disorder. Moreover, evidence suggests that milnacipran is effective and tolerable in the treatment of fibromyalgia and may have usefulness for fatigue and anxiety symptoms. The current paper reviews researches conducted to date that is relevant to the efficacy, tolerability, and mechanism of action of milnacipran in the treatment of depression, fibromyalgia, and other psychiatric syndromes. Future directions of research are also identified.

Factors impacting the selection of antidepressant treatment in patients with major depressive disorder at risk for nonadherence

Treatment with the newer generation antidepressants is considered generally effective for most patients with major depressive disorder when taken in accordance with treatment guidelines. However, multiple clinical studies have demonstrated that rates of patient adherence to antidepressants are inadequate, specifically with regard to long-term maintenance treatment. Tolerability issues associated with antidepressants can increase the risk for patient nonadherence and result in subsequent relapse of depressive symptoms. Comorbid symptoms of anxiety also influence psychiatrists' choice of antidepressants for patients with depression. Physicians can improve long-term patient outcomes for patients with major depressive disorder by considering the possibility of drug-drug interactions before prescribing a specific antidepressant.

Factors that impact choice of antidepressant treatment in medically complex patients

In medically complex patients with multiple comorbid illnesses who require concomitant medications, selecting the optimal antidepressant (ie, low risk of adverse effects and/or pharmacokinetic interactions) for an individual patient is critical for positive long-term patient outcomes. The serotonin-norepinephrine reuptake inhibitors (SNRls) are increasingly being used as first-line treatment for major depressive disorder (MDD) and may prove beneficial for treatment of medically complex patients.Thus, it is key for clinicians to evaluate the differences in the pharmacokinetic and tolerability profiles of the SNRI class of antidepressants, evaluating differences both within the class and compared with other antidepressants used to treat MDD.

In vitro inhibition and induction of human liver cytochrome p450 enzymes by milnacipran

Milnacipran (Savella) inhibits both norepinephrine and serotonin reuptake and is distinguished by a nearly 3-fold greater potency in inhibiting norepinephrine reuptake in vitro compared with serotonin. We evaluated the ability of milnacipran to inhibit and induce human cytochrome P450 enzymes in vitro. In human liver microsomes, milnacipran did not inhibit CYP1A2, 2B6, 2C8, 2C9, 2C19, or 2D6 (IC(50) >or= 100 microM); whereas, a comparator with dual reuptake properties [duloxetine (Cymbalta)] inhibited CYP2D6 (IC(50) = 7 microM) and CYP2B6 (IC(50) = 15 microM) with a relatively high potency. Milnacipran inhibited CYP3A4/5 in a substrate-dependent manner (i.e., midazolam 1'-hydroxylation IC(50) approximately 30 microM; testosterone 6beta-hydroxylation IC(50) approximately 100 microM); whereas, duloxetine inhibited both CYP3A4/5 activities with equal potency (IC(50) = 37 and 38 microM, respectively). Milnacipran produced no time-dependent inhibition (<10%) of P450 activity, whereas duloxetine produced time-dependent inhibition of CYP1A2, 2B6, 2C19, and 3A4/5. To evaluate P450 induction, freshly isolated human hepatocytes (n = 3) were cultured and treated once daily for 3 days with milnacipran (3, 10, and 30 microM), after which microsomal P450 activities were measured. Whereas positive controls (omeprazole, phenobarbital, and rifampin) caused anticipated P450 induction, milnacipran had minimal effect on CYP1A2, 2C8, 2C9, or 2C19 activity. The highest concentration of milnacipran (30 microM; >10 times plasma C(max)) produced 2.6- and 2.2-fold increases in CYP2B6 and CYP3A4/5 activity (making it 26 and 34% as effective as phenobarbital and rifampin, respectively). Given these results, milnacipran is not expected to cause clinically significant P450 inhibition or induction.

Milnacipran versus other antidepressive agents for depression

BACKGROUND

Although pharmacological and psychological interventions are both effective for major depression, antidepressant drugs are frequently used as first-line treatment in primary and secondary care settings. Milnacipran, a dual serotonin-norepinephrine reuptake inhibitor (SNRI), is one of the antidepressant drugs that clinicians use for routine depression care.

OBJECTIVES

To assess the evidence for the efficacy, acceptability and tolerability of milnacipran in comparison with tricyclic antidepressants (TCAs), heterocyclics, SSRIs and other newer antidepressive agents in the acute-phase treatment of major depression.

SEARCH STRATEGY

The Cochrane Collaboration Depression, Anxiety & Neurosis review group Controlled Trials Register (CCDANCTR-Studies and CCDANCTR-References) were electronically searched in August 2008. References of relevant trials and other reviews were also checked. Trial databases of the drug-approving agencies and ongoing clinical trial registers for all published and unpublished trials were hand-searched in 2007. All relevant authors were contacted for supplemental data. No language restriction was applied.

SELECTION CRITERIA

Randomised controlled trials comparing milnacipran with any other active antidepressive agents (including non-conventional agents such as herbal products like hypericum) as monotherapy in the acute phase of major depression were selected.

DATA COLLECTION AND ANALYSIS

Two reviewers independently checked eligibility, assessed methodological quality and extracted data from the eligible trials using a standardised data extraction form. The number of participants who responded to treatment or those who achieved remission were calculated on an intention-to-treat basis. Random-effects meta-analyses were conducted, combining data from the included trials.

MAIN RESULTS

A total of 16 randomised controlled trials (n=2277) were included in the meta-analysis.Despite the size of this sample, the pooled 95% confidence intervals were rather wide and there were no statistically significant differences in efficacy, acceptability and tolerability when comparing milnacipran with other antidepressive agents. However, compared with TCAs, patients taking milnacipran were associated with fewer dropouts due to adverse events (OR 0.55; 95%CI 0.35 to 0.85). There was also some weak evidence to suggest that patients taking milnacipran experienced fewer adverse events of sleepiness/ drowsiness, dry mouth or constipation compared with TCAs.

AUTHORS' CONCLUSIONS

Currently, there is inadequate evidence to conclude whether milnacipran is superior, inferior or the same as other antidepressive agents in terms of efficacy, acceptability and tolerability in the acute phase treatment of major depression. However, there is some evidence in favour of milnacipran over TCAs in terms of dropouts due to adverse events (acceptability) and the rates of experiencing adverse events (tolerability). Information about other clinically meaningful outcomes such as cost-effectiveness and social functioning, including the ability to return to work, is lacking. Further study is needed to answer whether milnacipran would be the better choice of antidepressant for acute major depression.

The Efficacy and Safety of Milnacipran for Treatment of Fibromyalgia. A Randomized, Double-blind, Placebo-controlled Trial

Objective.

To evaluate the safety and efficacy of milnacipran, a dual norepinephrine and serotonin reuptake inhibitor, in the treatment of fibromyalgia (FM).

Methods.

A 27-week, randomized, double-blind, multicenter study compared milnacipran 100 and 200 mg/day with placebo in the treatment of 888 patients with FM. Two composite responder definitions were used to classify each patient’s individual response to therapy. “FM responders” concurrently satisfied response criteria for improvements in pain (visual analog scale 24-h morning recall), patient global impression of change (PGIC), and physical functioning (SF-36 Physical Component Summary); while “FM pain responders” concurrently satisfied response criteria for improvements in pain and PGIC.

Results.

At the primary endpoint, after 3-month stable dose treatment, a significantly higher percentage of milnacipran-treated patients met criteria as FM responders versus placebo (milnacipran 200 mg/day, p = 0.017; milnacipran 100 mg/day, p = 0.028). A significantly higher percentage of patients treated with milnacipran 200 mg/day also met criteria as FM pain responders versus placebo (p = 0.032). Significant pain reductions were observed after Week 1 with both milnacipran doses. At 15 weeks, milnacipran 200 mg/day led to significant improvements over placebo in pain (realtime, daily and weekly recall; all measures, p < 0.05), PGIC (p < 0.001), fatigue (p = 0.016), cognition (p = 0.025), and multiple SF-36 domains. Milnacipran was safe and well tolerated by the majority of patients during 27 weeks of treatment; nausea and headache were the most common adverse events.

Conclusion.

Milnacipran is safe and effective for the treatment of multiple symptoms of FM.

Efficacy and tolerability of milnacipran in the treatment of major depression in comparison with other antidepressants : a systematic review and meta-analysis

BACKGROUND

Milnacipran, a dual serotonin-noradrenaline reuptake inhibitor, is one of the newer antidepressants that clinicians use for the routine care of patients with major depression. We undertook a systematic review and meta-analysis of randomized controlled trials that compared the efficacy and tolerability of milnacipran with other antidepressants.

OBJECTIVE

To assess the efficacy and tolerability of milnacipran in comparison with TCAs, SSRIs and other drugs in the acute phase of treatment for major depression.

METHODS

We searched the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials registers, journals, conference proceedings, trial databases of the drug-approving agencies and ongoing clinical trial registers for all published and unpublished randomized controlled trials that compared the efficacy and adverse events of milnacipran versus any other antidepressant. The search was conducted in December 2006 and updated in May 2007. No language restrictions were applied. All relevant authors were contacted to supplement any incomplete reporting in the original papers. Randomized controlled trials comparing milnacipran with any other active antidepressants as monotherapy in the acute phase of treatment for major depression were selected. Participants were aged > or =18 years, of both sexes and with a primary diagnosis of unipolar major depression. Studies were excluded when the participants had specific psychiatric and medical co-morbidities. Two independent reviewers assessed the quality of trials for inclusion, and subsequently extracted data. Disagreements were resolved by consensus. Meta-analyses were conducted for efficacy and tolerability outcomes. Sixteen randomized controlled trials (n = 2277) were included in the meta-analyses.

RESULTS

No differences were found in achieving clinical improvement, remission or overall tolerability when comparing milnacipran with other antidepressants. However, compared with the TCAs, fewer patients taking milnacipran were early treatment withdrawals due to adverse events (number needed to harm (NNH) = 15; 95% CI 10, 48). Significantly more patients taking TCAs experienced adverse events compared with milnacipran (NNH = 4; 95% CI 3, 7).

CONCLUSIONS

The overall effectiveness and tolerability of milnacipran versus other antidepressants does not seem to differ in the acute phase of treatment for major depression. However, there is some evidence in favour of milnacipran over TCAs in terms of premature withdrawal due to adverse events and the rates of patients experiencing adverse events. Milnacipran may benefit some patient populations who experience adverse effects from other antidepressants in the acute phase of treatment for major depression.

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.

Studies on the SAR and pharmacophore of milnacipran derivatives as monoamine transporter inhibitors

Derivatives of milnacipran were synthesized and studied as monoamine transporter inhibitors. Potent analogs were discovered at NET (9k) and at both NET and SERT (9s and 9u). A pharmacophore model was established based on the conformational analysis of milnacipran in aqueous solution using NMR techniques and was consistent with the SAR results.

Morphine glucuronosyltransferase activity in human liver microsomes is inhibited by a variety of drugs that are co-administered with morphine

Morphine is an analgesic drug used for the treatment of acute and chronic pain syndromes for cancer patients. Glucuronidation is a major pathway of the elimination of morphine in humans. Morphine is metabolized to 3-glucuronide (no analgesic effect) and 6-glucuronide (more potently analgesic than morphine) mainly by UGT2B7. In the present study, we investigated the inhibitory effects of a variety of drugs on the morphine glucuronosyltransferase activities in human liver microsomes. Twenty-one drugs including anticancer drugs, immunosuppressants, analgesics, anticonvulsants, antidepressants, antipsychotic drugs were selected in this study, because they are frequently co-administered with morphine. We found that 10 out of 21 drugs, tamoxifen, tacrolimus, diclofenac, carbamazepine, imipramine, clomipramine, amitriptyline, diazepam, lorazepam and oxazepam extensively inhibited the morphine 3- and 6-glucuronosyltransferase activities. Although some of the drugs are not substrates of UGT2B7, they would be potent inhibitors of UGT2B7. If patients receive morphine and these drugs simultaneously, the drug-drug interaction may change the levels of morphine and these glucuronides, resulting in altered analgesic efficacy and the risk of side effects. The results presented here will assist clinicians in choosing the proper drugs and/or dosages, and enable them to anticipate potential drug-drug interactions.

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.