What is Generic Carboxylate (Metadoxine)?
Metadoxine, also known as pyridoxine-pyrrolidone carboxylate, is a drug used to treat chronic and acute alcohol intoxication.[1] Metadoxine improved the clinical signs of acute alcohol intoxication and accelerated alcohol clearance from the blood [2] Metadoxine extended release is being evaluated as a treatment in human clinical trials for individuals with attention-deficit/hyperactivity disorder (ADHD) and for individuals with Fragile X Syndrome.[3] Metadoxine is an ion pair salt of Pyridoxine and L-Pyroglutamate. Pyridoxine (Vitamin B6) is a precursor of coenzymes including pyridoxal 5’-phosphate (PLP), which accelerates the metabolic degradation of ethanol and prevents adenosine triphosphate (ATP) inactivation by acetylaldehyde. Pyridoxal phosphate dependent enzymes also play a role in the biosynthesis of four important neurotransmitters: serotonin (5-HT), epinephrine, norepinephrine and GABA: see vitamin B6 metabolic functions. L-pyroglutamate (L-PGA) is present in the diet and is produced endogenously by enzymatic conversion of gamma-glutamyl amino acids to L-PGA and free amino acids. In the central nervous system (CNS), L-PGA was found to have a role in composition of neuro-active molecules. Its production has been linked to hepatic gamma-glutamyl transferase activity and levels of reduced glutathione (GSH). Lastly, it was shown that L-PGA facilitates ATP synthesis by stimulating de novo synthesis of purines.
Treatment for acute alcohol intoxication
In animal studies, metadoxine increased the activity of acetaldehyde dehydrogenase enzyme, prevented the decrease in alcohol dehydrogenase activity in chronic ethanol-fed rats, accelerated plasma and urinary clearance of ethanol, inhibited the increase of fatty acid esters in the liver of ethanol- treated rats, prevented the formation of fatty liver in rats exposed to a dose of ethanol sufficient to induce fatty liver, increased glutathione levels in the hepatocytes of acutely and chronically alcohol-intoxicated rats, prevented glutathione depletion, lipid peroxidation damage, collagen deposition, and TNF-α secretions induced by alcohol and acetaldehyde in hepatocytes and hepatic stellate cells.[1] In clinical studies, metadoxine has been reported to reduce half-life of ethanol in healthy volunteers and in acutely intoxicated patients; to accelerate the metabolism of alcohol and acetaldehyde into less toxic higher ketones and to improve their urinary clearance; to restore laboratory variables such as alcohol, ammonia, γ-GT, and alanine aminotransferase; and to improve clinical symptoms of alcohol intoxication, including psychomotor agitation, depression, aggressiveness, and equilibrium disorders.[1][2] There is also evidence that metadoxine has an effect on reducing craving for alcohol.[5] Data from clinical studies also support an effect of metadoxine on reducing indices of liver cell necrosis and fat accumulation in alcoholic fatty liver.[5]
As a medical treatment for alcohol intoxication and liver disease, metadoxine is typically given intravenously as immediate release formulation.
Treatment for liver disease
Metadoxine may block the differentiation step of preadipocytes by inhibiting CREB phosphorylation and binding to the cAMP response element, thereby repressing CCAAT/enhancer-binding protein b during hormone-induced adipogenesis.[6] Metadoxine, when given in an immediate release form in doses from 300 mg twice a day to 500 mg three times a day of up to 3 months, has been shown to improve biochemical indices of liver function as well as reduce ultrasonic evidence of fatty liver disease.
