Lafaxine

Uses

Lafaxine, a serotonin and norepinephrine reuptake inhibitor (SNRI), is used for the treatment of major depressive disorder (MDD). The efficacy of Lafaxine has been established in four short-term (8-week, placebo-controlled studies) and two maintenance studies in adult outpatients who met DSM-IV criteria for major depressive disorder.

Lafaxine is also used to associated treatment for these conditions: Hot Flushes, Major Depressive Disorder (MDD)

How Lafaxine works

Lafaxine, the active metabolite of venlafaxine, is a selective serotonin and norepinephrine reuptake inhibitor. Lafaxine inhibits neurotransmitter reuptake in serotonin, norepinephrine, and dopamine transporters. Lafaxine inhibits serotonin transporters with 10 times the affinity of norepinephrine transporters, and dopamine transporters with the lowest affinity. In vitro, desvenlafaxine has no inhibition of monoamine oxidase, and almost no affinity for muscarinic, cholinergic, H1-histaminergic, and alpha1-adrenergic receptors.

Dosage

Lafaxine dosage

The recommended dose for Lafaxineis 50 mg once daily, with or without food. The 50 mg dose is both a starting dose and the therapeutic dose. Lafaxine should be taken at approximately the same time each day. Tablets must be swallowed whole with fluid and not divided, crushed, chewed, or dissolved.In clinical studies, doses of 10 mg to 400 mg per day were studied.

In clinical studies, doses of 50 mg to 400 mg per day were shown to be effective, although no additional benefit was demonstrated at doses greater than 50 mg per day and adverse reactions and discontinuations were more frequent at higher doses.

The 25 mg per day dose is intended for a gradual reduction in dose when discontinuing treatment. When discontinuing therapy, gradual dose reduction is recommended whenever possible to minimize discontinuation symptoms

Side Effects

Suicidal thinking/ behaviour, HTN, mydriasis, seizure, hyponatraemia, interstitial lung disease and eosinophilic pneumonia; nausea, dizziness, insomnia, hyperhidrosis, constipation, somnolence, decreased appetite, anxiety, sexual function disorders in males (e.g. anorgasmia, decreased libido, abnormal orgasm, delayed ejaculation, erectile dysfunction, ejaculation disorder, ejaculation failure, sexual dysfunction).

Toxicity

Lafaxine is excreted in breast milk and as a result, nursing mothers must either stop the drug or stop breast feeding depending on the risks and benefit to mother and child.

Precaution

Patient with pre-existing HTN or other conditions that may be compromised by increased BP, raised intraocular pressure, personal or family history of mania or hypomania; CV, cerebrovascular or lipid metabolism disorders; seizure disorder. Avoid abrupt withdrawal. Renal and moderate to severe hepatic impairment. Pregnancy and lactation.

Interaction

Increased risk of bleeding with aspirin or other NSAIDs, warfarin and other anticoagulants.

Food Interaction

• Avoid alcohol.
• Avoid St. John's Wort.
• Take with or without food. The absorption is unaffected by food.

[Moderate] GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents.

Use in combination may result in additive central nervous system depression and
MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol.

Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

Lafaxine Hypertension interaction

[Moderate] Selective serotonin and norepinephrine reuptake inhibitor antidepressants (SNRIs) have been associated with sustained increases in blood pressure.

Therapy with SNRI antidepressants should be administered cautiously in patients with preexisting hypertension.

Blood pressure should be assessed prior to initiating treatment and monitored regularly.

The dose should be reduced or discontinued if necessary.

Lafaxine Drug Interaction

Major: amphetamine / dextroamphetamine, amphetamine / dextroamphetamine, duloxetine, escitalopram, lithium, lisdexamfetamine, bupropion, sertralineModerate: aripiprazole, lamotrigine, lurasidone, pregabalin, quetiapine, alprazolam, cetirizineUnknown: omega-3 polyunsaturated fatty acids, metoprolol, cyanocobalamin, ascorbic acid, cholecalciferol

Lafaxine Disease Interaction

Major: depression, renal diseaseModerate: glaucoma, hypertension, hyponatremia, mania, seizures, urinary tract obstruction

Volume of Distribution

3.4L/kg.

Elimination Route

Oral bioavailability is approximately 80% and is unaffected by food. Peak plasma concentration is reached in 7.5 hours.

Half Life

The mean terminal half life is 11.1 hours and may be prolonged in patients with renal and/or moderate to severe hepatic impairment.

Elimination Route

Lafaxine is mainly excreted in the urine. 45% of the dose is unchanged in the urine, 19% is excreted as a glucuronide metabolite, and 4. No dosage adjustment is necessary for gender, ethnicity, food, or combination with other psychotropics.

Pregnancy & Breastfeeding use

Pregnancy Category C. Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Contraindication

Concurrent use or within 14 days of discontinuing MAOIs (e.g. linezolid, IV methylene blue). Initiation of MAOI at least 7 days after discontinuing desvenlafaxine.

Special Warning

Hepatic impairment (Moderate to severe): 50 mg daily. Max: 100 mg once daily.

Renal Impairment:

• CrCl <30 or ESRD: 25 mg daily or 50 mg every other day. Supplemental doses should not be given after dialysis.
• CrCl (30-50): Max 50 mg once daily.

Storage Condition

Store between 20-25° C.

Innovators Monograph

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