A double-blind six months comparative study of milnacipran and clomipramine in major depressive disorder

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.

Open-label milnacipran for patients with persistent knee pain 1 year or longer after total knee arthroplasty: a pilot study

OBJECTIVE

The current study investigates whether milnacipran is effective in reducing pain and improving function in patients with persistent pain ≥ 1 year after total knee arthroplasty.

METHOD

This was a 12-week open-label study of flexibly dosed milnacipran in patients (N = 5) experiencing chronic persistent knee pain ≥ 1 year following total knee arthroplasty in the absence of new injury, infection, or implant failure. Subjects were identified from October 2010 to August 2011 through the Duke University Medical Center orthopedic clinic (Durham, North Carolina), typically during 1-year postoperative follow-up visits, and were referred by their orthopedic surgeon.

RESULTS

Milnacipran treatment was associated with reduction in pain according to the primary outcome measure of the visual analog scale (VAS) score for pain (effect size of 1.15) and secondary outcome measures of Knee Society Score (KSS) evaluation subscale score (effect size of 1.37) and Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) bodily pain subscale (effect size of 1.16) at week 12. Secondary outcome measures of functional change were mixed in such that, at week 12, the SF-36 physical functioning subscale showed improvement (effect size of 1.16), but the KSS function subscale score was just below the threshold for meaningful effect size (0.98).

CONCLUSIONS

Open-label milnacipran demonstrated reduced pain and some evidence of functional improvement in this small sample of patients with chronic persistent pain 1 year or more after total knee arthroplasty such that well-powered studies are warranted.

A 10-month, open-label evaluation of desvenlafaxine in outpatients with major depressive disorder

BACKGROUND

The primary objective was to evaluate the long-term safety of desvenlafaxine (administered as desvenlafaxine succinate) during open-label treatment in adult outpatients with a primary DSM-IV diagnosis of major depressive disorder (MDD).

METHOD

Depressed adult outpatients (≥ 18 years) who had completed 8-week, double-blind therapy (desvenlafaxine, venlafaxine extended release, or placebo) in a phase 3 study of desvenlafaxine for MDD received up to 10 months of open-label treatment with flexible-dose desvenlafaxine (200 to 400 mg/d). Safety assessments included physical examination, measurement of weight and vital signs, laboratory determinations, and 12-lead electrocardiogram recordings. Adverse events (AEs) and discontinuations due to AEs were monitored throughout the trial. The primary efficacy outcome was mean change from baseline on 17-item Hamilton Depression Rating Scale (HDRS-17) total score. The trial was conducted from August 2003 to March 2006.

RESULTS

The safety population included 1,395 patients who took at least 1 dose of open-label desvenlafaxine. Treatment-emergent AEs were reported by 1,238 of 1,395 patients (89%) during the open-label, on-therapy period. Treatment-emergent AEs reported by 10% or more patients were headache, nausea, hyperhidrosis, dizziness, dry mouth, insomnia, upper respiratory infection, nasopharyngitis, and fatigue. Adverse events were the primary reason for study discontinuation in 296 of 1,395 patients (21%). Ten patients (< 1%) had serious AEs that were considered possibly, probably, or definitely related to the study drug during the on-therapy period. No deaths occurred during the study.

CONCLUSIONS

Desvenlafaxine can be safely administered for up to 12 months. No new safety findings were observed in this study.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01309542.

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.

[Milnacipran and venlafaxine at flexible doses (up to 200 mg/d) in the outpatient treatment of adults with moderate-to-severe major depressive disorder: a 24-week randomised, double blind exploratory study]

INTRODUCTION

Serotonin (HT) and noradrenaline (NA) reuptake inhibitors (SNRIs) are commonly used as first line treatment of major depressive disorders (MDD). As compared to tricyclic antidepressants, they have proved similar efficacy and better tolerability. Milnacipran (MLN) (Ixel) and venlafaxine (VLF) (Effexor) are two SNRIs pharmacologically differing by their NA/HT ratio of potency: 1:1 and 1:30, respectively.

OBJECTIVES

To investigate the efficacy and safety/tolerability of MLN and VLF administered at flexible doses (100, 150 or 200 mg/day) for 24 weeks (including 4 weeks of up-titration) in the outpatient treatment of adults with moderate-to-severe MDD.

DESIGN

Multicentre, randomised, double blind, 2-parallel-arm, 24-week exploratory trial conducted in France by 50 psychiatrists. DIAGNOSIS AND MAIN INCLUSION CRITERIA: Male or female outpatients, aged 18 to 70, meeting the DSM-IV-TR and related MINI criteria for recurrent, unipolar, moderate-to-severe MDD, with neither psychotic features nor severe suicidal risk. A Montgomery-Asberg depression rating scale (MADRS) score> or =23 was required at inclusion. TREATMENT SCHEDULE: Patients were randomised to receive either MLN or VLF (1:1 ratio) for 24 weeks in double-blind conditions. Regardless of the treatment received, the following dosing schedule was applied: during the initial 4-week up-titration phase, the dosage was progressively increased from 25 mg/day (qd administration) to 150 mg/day (bid administration). At week 4, the dosage was either maintained at 150 mg/day, or adapted to 100 or 200 mg/day, based on the investigator's clinical judgement. At any time during the 20 following treatment weeks, the dose could be lowered for safety concerns until a minimal threshold of 100 mg/day. From Week 24, the dosage was decreased by 50mg/day every five days. After randomisation, eight assessment visits were organised at 2, 4, 6, 8, 12, 18, 24 weeks, and at study end (after the 5-15 days of down-titration and 10 days free of treatment). Efficacy evaluation ratings included the MADRS and global disease severity (CGI-S) total scores. Rates of MADRS response (reduction of initial score> or =50%) and remission (score< or =10) were calculated at Week 8 and Week 24 in the full analysis set as well as in the subgroups of patients with depressive disorder of severe DSM-IV intensity and with a MINI evaluation of suicidal risk (rated as required 'moderate' at the worst).

STATISTICAL ANALYSIS

Standard distribution statistics (including mean and standard deviation [S.D.]) of scores and their changes from baseline, were calculated using the observed-case (OC) approach at all assessment times for the MADRS score, and the last-observation-carried-forward (LOCF) at 8 and 24 weeks for both MADRS and CGI-S scores. MADRS response and remission rates at 8 and 24 weeks were calculated using the LOCF approach by normal approximation of the binomial distribution. Bilateral exploratory statistical tests at 5% significance level were performed for results at 8 and 24 weeks of: (i) MADRS score changes from baseline, based on the score progress at each visit (mixed model for repeated measurements [MMRM]), and (ii) global MADRS response and remission rates (Chi(2)). RESULTS AND PATIENTS: A total of 195 patients were randomly assigned MLN (n=97) or VLF (n=98) and 134 (68.7%: 61.9%/MLN and 75.5%/VLF) completed the trial. At the end of the up-titration, patients received 100 mg/day (11.4%/MLN, 10%/VLF), 150 mg/day (30.4%/MLN, 43.8%/VLF), or 200 mg/day (58.2%/MLN, 46.3%/VLF). Totals of 177 patients (90/MLN and 87/VLF) and 181 patients (90/MLN and 91/VLF) were analysed for efficacy and safety, respectively. Treatment groups were similar for baseline characteristics except a higher proportion of MLN patients with a severe depressive episode (63.3% versus 54%). RESULTS AND EFFICACY: MADRS score (mean [S.D.] initial score: 31 [4.5]) progressively decreased all along the treatment course and similarly in both groups (Week 8-OC : -18.8 [7.7]/MLN and -18.6 [7.3]/VLF, p(MMRM)=0.95 ; Week 24-OC : -23.1 [7.8]/MLN and -22.4 [7.3]/VLF, p(MMRM)=0.37 ). At week 8-LOCF, MADRS response rates were similar in both groups (64.4%/MLN, 65.5%/VLF, p(chi2)=0.88) as well as remission rates (42.2%/MLN, 42.5%/VLF p(chi2)=0.97). At week 24 they remained non clinically and statistically different between groups (response rates: 70%/MLN, 77%/VLF, p(chi2)=0.29; remission rates: 52.2%/MLN, 62.1%/VLF, p(chi2)=0.19). In both "severe depressive episode" and "MINI mild or moderate suicidal risk" subgroups (n=104 and 75, respectively), response and remission rates were non clinically different at both time points, however in the "MINI mild-to-moderate suicidal risk" subgroup, MLN tended to be more rapidly active (remission rate at week 8-LOCF: 44.7%/MLN, 35.1%/VLF). The changes in CGI-S were also indicative of a significant improvement of the global illness severity with both treatments. RESULTS AND SAFETY/TOLERABILITY: The tolerability profile of both drugs was in line with their pharmacological activity. About 70% of patients in both groups experienced at least one adverse event (AE). In both groups, the most common AEs were nausea, dizziness, headache and hyperhidrosis, and, in the male patients, genito-urinary problems: orgasmic disorders (VLF only) and dysuria (MLN only). These AEs were mostly responsible for definitive treatment discontinuation for tolerability concerns. None of the 6 serious adverse events (SAEs) on MLN and 4 of the 8 SAEs on VLF were related to the test drug.

CONCLUSION

MLN and VLF at flexible doses up to 200 mg/day globally exhibited similar efficacy and tolerability profiles in the long-term treatment of adults with MDD.

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.

Psychopharmacology of depression in the next millennium

Over the last half of the 20th century, there have been a series of psychopharmacologic strategies for treatment of depression. As we approach the next century, new therapies in varying stages of American release are being developed. This review will focus on information available for the following proposed antidepressants: 1) reboxetine, a norepinephrine selective reuptake inhibitor; 2) milnacipran, a combined serotonin/norepinephrine reuptake inhibitor; 3) a new enantiomer of fluoxetine, a selective serotonin reuptake inhibitor; 4) duloxetine, another combined serotonin/norepinephrine reuptake inhibitor; 5) sunepitron, a combined 5-HT1A agonist and a2 antagonist; and 6) MK-869, a substance P inhibitor. Finally, other possible developing directions will be reviewed, including corticotropin-releasing factor.