Overview
Pyridoxine (Vitamin B6) is an essential water-soluble vitamin that functions as a coenzyme in numerous metabolic processes, including amino acid metabolism, neurotransmitter synthesis, and hemoglobin formation. It is used to treat and prevent vitamin B6 deficiency and certain metabolic disorders. Vitamin B6 is generally well-tolerated at recommended doses but can cause neurotoxicity at high doses.
Mechanism of Action
Pyridoxine (Vitamin B6) acts as a coenzyme in the form of pyridoxal phosphate (PLP), which is involved in over 100 enzymatic reactions. Key functions include amino acid metabolism (transamination, decarboxylation), neurotransmitter synthesis (serotonin, dopamine, GABA), glycogen phosphorylase activity, and heme biosynthesis.
Indications
- Treatment and prevention of vitamin B6 deficiency
- Certain inborn errors of metabolism (e.g., homocystinuria, pyridoxine-dependent seizures)
- Sideroblastic anemia
- Nausea and vomiting of pregnancy (off-label use)
- Peripheral neuropathy associated with isoniazid therapy
Common Doses
- 10 mg
- 25 mg
- 50 mg
- 100 mg
- As part of multivitamin combinations in various strengths
Dosage
Typical adult dosage for deficiency is 10-25 mg daily. For specific conditions like isoniazid-induced neuropathy, 25-50 mg daily may be used. Pediatric doses vary by age and indication. The provided extract describes administration via dropper for pediatric multivitamin drops: use full dosage unless otherwise directed, can be given directly or mixed with food/liquids.
Contraindications
- Hypersensitivity to pyridoxine or any component of the formulation
Side Effects
- Generally well-tolerated at recommended doses
- With high doses: sensory neuropathy, ataxia, numbness, perioral tingling
- Rare: photosensitivity, headache, nausea, abdominal pain
- Very high doses may cause hepatotoxicity
Interactions
- Isoniazid, penicillamine, cycloserine, hydralazine: may increase pyridoxine requirements
- Levodopa: pyridoxine may decrease effectiveness (except when used with carbidopa)
- Phenobarbital, phenytoin: pyridoxine may decrease serum levels
Counseling Points
- Take as directed; do not exceed recommended dose without medical supervision
- High doses can cause nerve damage with symptoms like numbness or tingling
- Store away from direct sunlight and moisture
- For pediatric drops: shake well before use, can mix with food or liquids if needed
- Inform healthcare provider of all medications/supplements being taken