Milnacipran

Milnacipran undergoes minimal CYP450 related metabolism, with the majority of the dose excreted unchanged in urine (55%) and has a low binding to plasma proteins (13%). In vitro and in vivo studies showed that milnacipran hydrochloride is unlikely to be involved in clinically significant pharmacokinetic drug interactions [see Pharmacokinetics in Special Populations ( 12.3 )] . • Milnacipran hydrochloride is unlikely to be involved in clinically significant pharmacokinetic drug interactions ( 7 ). • Pharmacodynamic interactions of milnacipran hydrochloride with other drugs can occur ( 7 ).

7.1 Monoamine Oxidase Inhibitors (MAOIs) The concomitant use of SSRIs and SNRIs, including milnacipran hydrochloride, with MAOIs increases the risk of serotonin syndrome. The use of MAOIs intended to treat psychiatric disorders with milnacipran hydrochloride or within 5 days of stopping treatment with milnacipran hydrochloride is contraindicated. The use of milnacipran hydrochloride within 14 days of stopping an MAOI intended to treat psychiatric disorders is also contraindicated. In addition, do not initiate milnacipran hydrochloride in a patient who is being treated with MAOIs such as linezolid or intravenous methylene blue.

No reports involved the administration of methylene blue by other routes (such as oral tablets or local tissue injection). If it is necessary to initiate treatment with a MAOI such as linezolid or intravenous methylene blue in a patient taking milnacipran hydrochloride, discontinue milnacipran hydrochloride before initiating treatment with the MAOI [see Dosage and Administration ( 2.5 , 2.6 ), Contraindications ( 4 ), Drug Interactions ( 7.1 )] .

7.2 Serotonergic Drugs Serotonin syndrome can occur with use of milnacipran hydrochloride and other serotonergic drugs (other SNRIs, SSRIs, triptans, tricyclic antidepressants, opioids, lithium, tryptophan, buspirone, amphetamines, and St. John’s Wort), or with drugs that impair metabolism of serotonin (i.e., monoamine oxidase inhibitors). Advise patients of the signs and symptoms associated with serotonin syndrome and to seek medical care immediately if they experience these symptoms [see Dosage and Administration ( 2.5 , 2.6 ), Warnings and Precautions ( 5.2 )] .

7.3 Triptans There have been rare postmarketing reports of serotonin syndrome with use of an SSRI and a triptan. If concomitant treatment of milnacipran hydrochloride with a triptan is clinically warranted, careful observation of the patient is advised, particularly during treatment initiation and dose increases [see Warnings and Precautions ( 5.2 )] .

7.4 Catecholamines Milnacipran hydrochloride inhibits the reuptake of norepinephrine. Therefore, concomitant use of milnacipran hydrochloride with epinephrine and norepinephrine may be associated with paroxysmal hypertension and possible arrhythmia [see Warnings and Precautions ( 5.3 , 5.4 )] .

7.5 CNS-active drugs Given the primary CNS effects of milnacipran hydrochloride, use caution when it is taken in combination with other centrally acting drugs, including those with a similar mechanism of action. Clomipramine: In a drug-drug interaction study, an increase in euphoria and postural hypotension was observed in patients who switched from clomipramine to milnacipran hydrochloride.

7.6 Clinically Important Interactions with Select Cardiovascular Agents Digoxin: Use of milnacipran hydrochloride concomitantly with digoxin may be associated with potentiation of adverse hemodynamic effects. Postural hypotension and tachycardia have been reported in combination therapy with intravenously administered digoxin (1 mg). Avoid co-administration of milnacipran hydrochloride and intravenous digoxin [see Warnings and Precautions ( 5.3 , 5.4 )] . Clonidine: Because milnacipran hydrochloride inhibits norepinephrine reuptake, co-administration with clonidine may inhibit clonidine’s anti-hypertensive effect.

7.7 Drugs that Interfere with Hemostasis Concomitant use of milnacipran hydrochloride with an antiplatelet or anticoagulant drug (e.g., NSAIDs, aspirin, and warfarin) may potentiate the risk of bleeding. This may be due to the effect of milnacipran hydrochloride on the release of serotonin by platelets. Closely monitor for bleeding for patients receiving an antiplatelet or anticoagulant drug when milnacipran hydrochloride is initiated or discontinued [see Warnings and Precautions ( 5.9 )] .

8.1 Pregnancy Risk Summary Based on data from published observational studies, exposure to SNRIs, particularly in the month before delivery, has been associated with a less than 2-fold increase in the risk of postpartum hemorrhage [see Warnings and Precautions ( 5.2 )] . The available data on milnacipran hydrochloride use in pregnant women are insufficient to evaluate for a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes.

There are risks associated with exposure to serotonin and norepinephrine reuptake inhibitors (SNRIs) and selective-serotonin reuptake inhibitors (SSRIs), including milnacipran hydrochloride, during pregnancy (see Clinical Considerations). Animal reproduction studies have been performed in rats, rabbits and mice. Milnacipran was shown to increase embryofetal and perinatal lethality in rats and the incidence of a minor skeletal variation in rabbits at doses below (rat) or approximately equal to (rabbit) the maximum recommended human dose (MRHD) of 200 mg/day on a mg/m 2 basis.

No effects were seen in mice when treated with milnacipran during the period of organogenesis at doses up to 3 times the MHRD on a mg/m 2 basis (see Data). The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%-4% and 15%-20%, respectively.

Clinical Consideration Maternal adverse reactions Use of milnacipran hydrochloride in the month before delivery may be associated with an increased risk of postpartum hemorrhage [see Warnings and Precautions ( 5.9 )]. Fetal/Neonatal adverse reactions Neonates exposed to SNRIs or SSRIs, including milnacipran hydrochloride, late in the third trimester have developed complications requiring prolonged hospitalization, respiratory support, and tube feeding. Such complications can arise immediately upon delivery.

Reported clinical findings have included respiratory distress, cyanosis, apnea, seizures, temperature instability, feeding difficulty, vomiting, hypoglycemia, hypotonia, hypertonia, hyperreflexia, tremor, jitteriness, irritability, and constant crying. These findings are consistent with either direct toxic effect of SSRIs and SNRIs or possibly, a drug discontinuation syndrome. It should be noted that, in some cases, the clinical picture is consistent with serotonin syndrome [see Warnings and…