Metadoxine is a pyridoxine-pyrrolidone carboxylate complex, primarily indicated for the management of acute alcohol intoxication and chronic alcoholism. It acts as an alcohol dehydrogenase (ADH) activator and aldehyde dehydrogenase (ALDH) inhibitor, accelerating ethanol metabolism and reducing acetaldehyde accumulation. It also exhibits hepatoprotective and antioxidant properties, making it useful in alcoholic liver disease. In the Indian context, it is widely prescribed for alcohol-related disorders and as an adjuvant in fatty liver disease.
Adult: 500mg to 1000mg (1-2 tablets of 500mg) orally, twice daily. For acute intoxication: 1000mg (2 tablets) as a single dose, may be repeated once after 6-8 hours if needed.
Note: Tablet should be swallowed whole with a full glass of water, with or without food. For best results in chronic use, take at consistent times daily. Do not crush or chew.
Metadoxine exerts its primary effect by modulating the enzymes involved in ethanol metabolism. It increases the activity of alcohol dehydrogenase (ADH), accelerating the conversion of ethanol to acetaldehyde. Simultaneously, it inhibits aldehyde dehydrogenase (ALDH), slowing the conversion of acetaldehyde to acetate. This 'accelerated displacement' helps clear ethanol from the blood more rapidly while the transiently elevated acetaldehyde may contribute to an aversive effect. It also exhibits direct hepatoprotective effects by reducing fatty infiltration, inhibiting collagen deposition, and acting as an antioxidant and free radical scavenger.
Pregnancy: Category C: Animal studies are insufficient. There are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus. Not recommended.
Driving: May cause dizziness or drowsiness, especially when used for acute intoxication. Patients should be cautioned about operating machinery or driving until they know how the medication affects them.
| Levodopa | Pyridoxine can decrease the efficacy of levodopa by enhancing its peripheral decarboxylation. Metadoxine may reduce levodopa's antiparkinsonian effect. | Major |
| Phenobarbital / Phenytoin | Pyridoxine may decrease serum levels of these antiepileptics, potentially reducing seizure control. | Moderate |
| Isoniazid (INH) | Isoniazid is a pyridoxine antagonist. Concomitant use may increase the requirement for pyridoxine, potentially reducing Metadoxine's efficacy for its primary indication. | Moderate |
| Disulfiram | Both drugs affect aldehyde metabolism. Concomitant use may lead to exaggerated acetaldehyde syndrome (flushing, tachycardia, nausea). Use with extreme caution. | Major |
| CNS Depressants (Benzodiazepines, Opioids) | Additive sedative effect, especially when used for acute intoxication. | Moderate |