Medication Summary
Use of L-carnitine in primary carnitine deficiency restores plasma carnitine levels to nearly normal, but muscle carnitine levels rise slightly. Muscle function can be normalized in patients with carnitine deficiency when muscle carnitine levels remain less than 10% of controls. Cardiomyopathy often responds well to carnitine supplementation. Carnitine supplementation in fatty acid oxidation disorders and other organic acidurias is to correct carnitine deficiency and to allow removal of toxic intermediates. The other goal of therapy is to restore CoA levels. Carnitine therapy for long-chain fatty acid oxidation defects has become questionable because it promotes formation of long-chain acylcarnitines that may cause arrhythmogenesis and membrane dysfunction. Carnitine supplementation in total parenteral nutrition (TPN) prevents secondary carnitine deficiency in preterm newborns.
Dietary supplements
Class Summary
At high doses, L-carnitine corrects severe carnitine depletion and associated metabolic abnormalities observed in primary carnitine deficiency and enables the production of ketone bodies during fasting. In secondary carnitine deficiency, carnitine enhances excretion of toxic metabolites and generation of free CoA.
Levocarnitine (Carnitor, L-Carnitine)
An amino acid derivative synthesized from methionine and lysine, required in energy metabolism. Can promote excretion of excess fatty acids in patients with defects in fatty acid metabolism or specific organic acidopathies, which bioaccumulate acyl CoA esters. Normal levels occur in liver, and mild level increases occur in skeletal muscle. May cause reversal of skeletal and heart muscle abnormalities.
Dextrose (D10W, D-glucose)
Monosaccharide absorbed from intestines and distributed, stored, and used by tissues.
Parenterally injected dextrose is used in patients unable to sustain adequate PO intake. Direct PO absorption results in a rapid increase in blood glucose concentrations. Dextrose is effective in small doses. Concentrated dextrose infusions provide higher amounts of glucose and increased caloric intake in a small volume of fluid.
Riboflavin (Vitamin B-2)
Essential in activation of pyridoxine and conversion of tryptophan to niacin; component of flavoprotein enzymes, which are necessary for tissue respiration. Riboflavin functions as a cofactor for electron transport in complex I, complex II, and in the electron transfer of flavoprotein. It has proven useful for the treatment of some patients with SCAD deficiency, riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency, and milder forms of glutaric aciduria type II.
Betaine (Cystadane)
Methyl group donor used in the treatment of homocystinuria. Decreases elevated homocysteine blood levels. Used for conditions that can cause hyperhomocysteinemia and secondary carnitine deficiency (ie, cobalamin C deficiency).
Hydroxocobalamin (Vitamin B-12, Hydro cobex)
Deoxyadenosylcobalamin and hydroxocobalamin are active forms of vitamin B-12 in humans. Vitamin B-12 synthesized by microbes but not humans or plants. Vitamin B-12 deficiency may result from intrinsic factor deficiency (pernicious anemia), partial or total gastrectomy, or diseases of the distal ileum. Used to treat conditions caused by altered cobalamin metabolism that may cause secondary carnitine deficiency (ie, cobalamin C deficiency).
Ubidecarenone (CoQ-10, Coenzyme Q, Ubiquinone)
Coenzyme involved in mitochondrial energy production. Controls flow of oxygen within individual cells. Has essential antioxidant and membrane-stabilizing properties.
Glycine (Aminoacetic acid)
The simplest amino acid that helps improve glycogen storage is used in the synthesis of hemoglobin, collagen, and glutathione, and it facilitates the amelioration of high blood fat and uric acid levels. Glycine is primarily used for the treatment of isovaleric acidemia, which is an organic acidemia that causes secondary carnitine depletion.
Biotin
Water-soluble vitamin, generally classified as a B-complex vitamin. An essential coenzyme in fat metabolism and in other carboxylation reactions. Used for the treatment of biotin responsive propionic acidemia, which can lead to secondary carnitine deficiency.
