The total body content of carnitine is about 20 grams (0.71 oz) in a person weighing 70 kilograms (150 lb), with nearly all of it contained within skeletal muscle cells. Carnitine metabolizes at rates of about 400 μmol (65mg) per day, an amount less than 1% of total body stores. Deficiency
Carnitine deficiency is rare in healthy people without metabolic disorders, indicating that most people have normal, adequate levels of carnitine normally produced through fatty acid metabolism. One study found that vegans showed no signs of carnitine deficiency. Infants, especially premature infants, have low stores of carnitine, necessitating use of carnitine-fortified infant formulas as a replacement for breast milk, if necessary.Two types of carnitine deficiency states exist. Primary carnitine deficiency is a genetic disorder of the cellular carnitine-transporter system that typically appears by the age of five with symptoms of cardiomyopathy, skeletal-muscle weakness, and hypoglycemia. Secondary carnitine deficiencies may happen as the result of certain disorders, such as chronic kidney failure, or under conditions that reduce carnitine absorption or increase its excretion, such as the use of antibiotics, malnutrition, and poor absorption following digestion. Supplementation
Despite widespread interest among athletes to use carnitine for improvement of exercise performance, inhibit muscle cramps, or enhance recovery from physical training, the quality of research for these possible benefits has been low, prohibiting any conclusion of effect. At supplement amounts of 2–6 grams (0.071–0.212 oz) per day over a month, there was no consistent evidence that carnitine affected exercise or physical performance.
It is also a drug approved by the Food and Drug Administration to treat primary and certain secondary carnitine-deficiency syndromes secondary to inherited diseases. Drug interactions and adverse effects
Carnitine interacts with pivalate-conjugated antibiotics such as pivampicillin. Chronic administration of these antibiotics increases the excretion of pivaloyl-carnitine, which can lead to carnitine depletion. Treatment with the anticonvulsants valproic acid, phenobarbital, phenytoin, or carbamazepine significantly reduces blood levels of carnitine.When taken in the amount of roughly 3 grams (0.11 oz) per day, carnitine may cause nausea, vomiting, abdominal cramps, diarrhea, and body odor smelling like fish. Other possible adverse effects include skin rash, muscle weakness, or seizures in people with epilepsy. History
Levocarnitine was approved by the U.S. Food and Drug Administration as a new molecular entity under the brand name Carnitor on December 27, 1985. See also
Acetylcarnitine
Gamma-butyrobetaine dioxygenase
Glycine Propionyl-l-Carnitine (GPLC)
Meldonium
Systemic primary carnitine deficiency


== References ==