Carnitine (Sean Graham , University of Mississippi School of Pharmacy

Carnitine

Common names: (L-carnitine, Acetyl-L-carnitine, Bicarnesine, and Carnitor) Scientific name: (L-3-hydroxytrimethylaminobutanoate)

History

L-carnitine is a naturally occurring, nonprotein amino acid that is biosynthesized in the liver and kidneys from the essential amino acids lysine and methionine. The generic term "carnitine" originates from the Latin carnus (flesh), as the compound was originally isolated from meat, and refers to the group of carnitine derivatives: L-carnitine, acetyl-L-carnitine, and propionyl-Lcarnitine. Dextro- forms also exist; however, only the levo-isomers are biologically active in humans. In 1989, the US Food and Nutrition Board of the Institute of Medicine determined that carnitine was not an essential nutrient and has not established a recommended dietary allowance for the compound.1

MOA

L-carnitine facilitates beta-oxidation of long-chain fatty acids by transporting them into the mitochondria to be oxidized, which produces energy. It also exports short- and medium-chain fatty acids as well as toxic compounds from the mitochondria that accumulate as a result of normal and abnormal metabolism.1

Uses

The US Food and Drug Administration (FDA) has approved oral and intravenous (IV) Lcarnitine for the treatment of primary and secondary carnitine deficiency because of inborn errors of metabolism. IV L-carnitine is also approved for the treatment of carnitine deficiency resulting from dialysis in patients with end-stage renal disease.2

Dosage forms and typical dosing

Comes in intravenous and oral dosage forms. Most commonly dosage 3-4 grams per day for most of its indications.1

Adverse events and toxicities

Nausea, vomiting, abdominal cramps, diarrhea, and a "fishy" body odor can occur with doses of about 3 g/day. Less common adverse effects have included pruritic rash, muscle weakness in uremic patients, and seizures in patients with seizure disorders. The IV median lethal dose (LD50) of levo carnitine in rats is 5.4 g/kg, and the oral LD 50 of levocarnitine in mice is 19.2 g/kg.1

Interactions

Carbamazepine, phenobarbital, phenytoin, and valproic acid may decrease blood concentrations of carnitine in children treated for convulsions. Pivampicillin and other pivalate-conjugated antibiotics may decrease blood concentrations of carnitine and limit fatty acid oxidation.1

Safety and effectiveness

There have been no reports of a levocarnitine overdosage; however, large doses may cause diarrhea. Carnitine has been commercially advertised to improve exercise performance, enhance a sense of wellbeing, and to aid weight loss; however, clinical trials have not consistently supported these uses. Limited clinical data support Lcarnitine as an effective therapy for improving sperm quality for men with oligoasthenozoospermia.1

Professional opinion

As a naturally occurring amino acid, carnitine is a safe supplement and the depletion of which can have a negative impact on health. The function of carnitine is mostly facilitating long chain fatty acids and humans can run low on this amino acid especially in patients with CRD needing dialysis. If it’s the unadulterated version of L-carnitine, supplementation can be helpful to patients with only minor GI upset adverse effects. ~ S. Graham

References

1.Login. Online.lexi.com. https://online.lexi.com/lco/action/doc/retrieve/docid/fc_rnp2/6032226?cesid=0RDA4L7mASe &searchUrl=%2Flco%2Faction%2Fsearch%3Fq%3Dcarnitine%26t%3Dname%26va%3Dcarniti ne. Published 2022. Accessed March 4, 2022. 2.Micromedex Products: Please Login. Micromedexsolutions.com. https://www.micromedexsolutions.com/micromedex2/librarian/PFDefaultActionId/evidence xpert.DoIntegratedSearch?navitem=topHome&isToolPage=true#. Published 2022. Accessed March 4, 2022. 3. Gnoni A, Longo S, Gnoni G, Giudetti A. Carnitine in Human Muscle Bioenergetics: Can Carnitine Supplementation Improve Physical Exercise?

Pictures: https://www.amazon.com/Natures-Bounty%C2%AE-L-Carnitine-500-Tablets/dp/B000KOOARU