Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Levomefolic acid (INN, also known as L-5-MTHF, L-methylfolate and L-5-methyltetrahydrofolate and (6S)-5-methyltetrahydrofolate, and (6S)-5-MTHF) is the primary biologically active form of folate used at the cellular level for DNA reproduction, the cysteine cycle and the regulation of homocysteine. It is also the form found in circulation and transported across membranes into tissues and across the blood–brain barrier. In the cell, L-methylfolate is used in the methylation of homocysteine to form methionine and tetrahydrofolate (THF). THF is the immediate acceptor of one carbon unit for the synthesis of thymidine-DNA, purines (RNA and DNA) and methionine. The un-methylated form, folic acid (vitamin B9), is a synthetic form of folate, and must undergo enzymatic reduction by dihydrofolate reductase (DHFR) to become biologically active.
It is synthesized in the absorptive cells of the small intestine from polyglutamylated dietary folate. It is a methylated derivative of tetrahydrofolate.
L-Methylfolate is water-soluble and primarily excreted via the kidneys. In a study of 21 subjects with coronary artery disease, peak plasma levels were reached in one to three hours following oral or parenteral administration. Peak concentrations were found to be more than seven times higher than folic acid (129 ng/ml vs. 14.1 ng/ml).
In March 2012, Merck & Cie of Switzerland, Pamlab LLC (maker of Metanx and Cerefolin, Neevo DHA, and Deplin), and South Alabama Medical Science Foundation (SAMSF) (the plaintiffs) filed a complaint in the United States District Court for the Eastern District of Texas against four defendants: Macoven Pharmaceuticals (owned by Pernix Therapeutics), Gnosis SpA of Italy, Gnosis U.S.A and Gnosis Bioresearch Switzerland. The plaintiffs alleged that the defendants infringed on several of the plaintiffs' patents. The Macoven products named in the suit are: "Vitaciric-B", "ALZ-NAC", "PNV DHA", and l-methylfolate calcium (levomefolate calcium).
In September 2012, the same three plaintiffs filed a complaint requesting that the International Trade Commission begin an 19 U.S.C. § 1337 investigation of the same four defendants. The complaint states that Gnosis' "Extrafolic-S" and products which are made from it, infringe upon three of their patents: US 5997915, US 6673381, and US 7172778.
Levomefolate calcium, a calcium salt of levomefolic acid is sold under the brand name Metafolin and incorporated in Deplin. Levomefolate magnesium is a magnesium salt of levomefolic acid, sold under the brand name Enlyte or Enlyte D.
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^The six patents named were US 5997915, US 6011040, US 6254904, US 6673381, US 7674490 and US 7172778.
^"Pernix Therapeutics' Subsidiary Macoven Pharmaceuticals, LLC Named in Suit by Merck, Pamlab, L.L.C. and Others for Alleged". Bloomberg. 6 March 2012. Retrieved 1 October 2012.
^Schweibenz EW (10 September 2012). "SAMSF, Merck, and Pamlab File New 337 Complaint Regarding Certain Reduced Folate Nutraceutical Products and L-methylfolate Raw Ingredients Used Therein". Oblon, Spivak, McClelland, Maier & Neustadt, L.L.P. Archived from the original on 1 October 2012.
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^"Enlyte". l-methylfolate. Retrieved 14 September 2017.
CALCIUM L-5-METHYLTETRAHYDROFOLATE (L-5-MTHF-Ca)
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