Milnacipran

Depression

In a pooled analysis of 7 comparative trials with imipramine, milnacipran and imipramine were shown to have comparable efficacy while milnacipran was significantly better tolerated. A pooled analysis of studies comparing milnacipran and SSRIs concluded a superior efficacy for milnacipran with similar tolerability for milnacipran and SSRIs. A more recent meta-analysis of 6 studies involving more than 1,000 patients showed no distinction between milnacipran and SSRIs in efficacy or discontinuation rates, including discontinuation for side effects or lack of efficacy. A meta-analysis of a total of 16 randomized controlled trials with more than 2200 patients concluded that there were no statistically significant differences in efficacy, acceptability and tolerability when comparing milnacipran with other antidepressant agents. However, compared with TCAs, significantly fewer patients taking milnacipran dropped out due to adverse events. As with other antidepressants, 1 to 3 weeks may elapse before significant antidepressant action becomes clinically evident.

Fibromyalgia

During its development for fibromyalgia, milnacipran was evaluated utilizing a composite responder approach. To be considered as a responder for the composite ‘treatment of fibromyalgia’ endpoint, each patient had to show concurrent and clinically meaningful improvements in pain, physical function and global impression of disease status. A systematic review in 2012 showed moderate relief for a minority of people with fibromyalgia. Milnacipran was associated with increased adverse events and discontinuing use of the drug.

Side effects

The most frequently occurring adverse reactions (≥ 5% and greater than placebo) were nausea, headache, constipation, dizziness, insomnia, hot flush, hyperhidrosis, vomiting, palpitations, heart rate increase, dry mouth, and hypertension [FDA Savella prescribing information]. Milnacipran can have a significant impact on sexual functions, including both a decrease in sexual desire and ability. Milnacipran can cause pain of the testicles in men. The incidence of cardiovascular and anticholinergic side effects was significantly lower compared to TCAs as a controlled study with over 3,300 patients revealed. Elevation of liver enzymes without signs of symptomatic liver disease has been infrequent. Mood swing to mania has also been seen and dictates termination of treatment. In psychotic patients emergence of delirium has been noticed. Milnacipran has a low incidence of sedation but improves sleep (both duration and quality) in depressed patients. In agitated patients or those with suicidal thoughts additive sedative/anxiolytic treatment is usually indicated.

Interactions

Contraindications

Administration of milnacipran should be avoided in individuals with the following:

Administration of milnacipran should be done with caution in individuals with the following:

Milnacipran should not be used during pregnancy because it may cross the placenta barrier and no clinical data exists on harmful effects in humans and animal studies. Milnacipran is contraindicated during lactation because it is excreted in the milk, and it is not known if it is harmful to the newborn.

Pharmacology

Milnacipran inhibits the reuptake of serotonin and norepinephrine in an approximately 1:3 ratio, respectively; in practical use this means a relatively balanced action upon both neurotransmitters. Increasing both neurotransmitters concentration simultaneously works synergistically to treat both depression and fibromyalgia. Milnacipran exerts no significant actions on H₁, α₁, D₁, D₂, and mACh receptors, as well as on benzodiazepine and opioid binding sites.

Recently, levomilnacipran has been found to act as an inhibitor of beta-site amyloid precursor protein cleaving enzyme-1 (BACE-1), which is responsible for β-amyloid plaque formation, and hence may be a potentially useful drug in the treatment of Alzheimer's disease. Other BACE-1 inhibitors, such as CTS-21166 (ASP1720), MK-8931, and AZD3293 are currently in clinical trials for the treatment of Alzheimer's disease.

Pharmacokinetics

Milnacipran is well absorbed after oral dosing and has a bioavailability of 85%. Meals do not have an influence on the rapidity and extent of absorption. Peak plasma concentrations are reached 2 hours after oral dosing. The elimination half-life of 8 hours is not increased by liver impairment and old age, but by significant renal disease. Milnacipran is conjugated to the inactive glucuronide and excreted in the urine as unchanged drug and conjugate. Only traces of active metabolites are found.

Regulatory status

Milnacipran is indicated for:

The recommended dose for depression is 100 mg/day (given as 50 mg 2 times daily), with a starting period of 4 days on 25 mg/day. The dose should be decreased in patients with renal disease. The recommended dose for fibromyalgia is 100 mg/day (after an uptitration period ) which may be increased to 200 mg/day based on individual patient response.

After successful treatment of the acute depressive episode, patients should be maintained on milnacipran for several months (normally 9 months) in order to prevent relapse of depression.

In the United States, Savella is supplied by Forest Pharmaceuticals in a 2-week, professional sample titration pack to be provided directly by the doctor to the patient initiating milnacipran therapy. This pack contains five 12.5 mg tablets (one on day one, one tablet twice a day on days 2-3), eight 25 mg tablets (one tablet twice a day on days 4–7), and fourteen 50 mg tablets (one tablet twice a day on days 8–14). Therapy is then continued with one 50 mg tablet twice a day, or adjusted as needed by the physician.

History

Milnacipran was first approved for the treatment of major depressive episodes in France in December 1996. It is currently marketed (as Ixel) for this indication in over 45 countries worldwide including several European countries such as Austria, Bulgaria, Finland, France, Portugal, and Russia. It is also available in Japan (as Toledomin) and Mexico (as Dalcipran). Cypress Bioscience bought the exclusive rights for approval and marketing of the drug for any purpose in the United States and Canada in 2003 from the manufacturer Laboratoires Pierre Fabre.

In January 2009 the U.S. Food and Drug Administration (FDA) approved milnacipran (under the brand name Savella) only for the treatment of fibromyalgia, making it the third medication approved for this purpose in the United States. In July and November 2009, the European Medicines Agency refused marketing authorization for a milnacipran product (under the brand name Impulsor) for the treatment of fibromylagia.