Pyridoxine hydrochloride
(Vitamin B ₆)
Pyridoxine hydrochloride (Vitamin B ₆)
Vitamin B ₆ Nestrex
Pyridoxine hydrochloride
(peer-ih- DOX-een)
Pregnancy Category: A (C for doses that exceed the RDA) Aminoxin Nestrex (Rx: Injection; OTC: Tablets)

Classification: Vitamin B complex

Action/Kinetics: A water-soluble, heat-resistant vitamin that is destroyed by light. Acts as a coenzyme in the metabolism of protein, carbohydrates, and fat. As the amount of protein increases in the diet, the pyridoxine requirement increases. However, pyridoxine deficiency alone is rare. t 1/2: 2-3 weeks. Metabolized in the liver and excreted through the urine.

Uses: Pyridoxine deficiency including poor diet, drug-induced (e.g., oral contraceptives, isoniazid), and inborn errors of metabolism. Investigational: Hydrazine poisoning, PMS, high urine oxalate levels, N&V; due to pregnancy, carpal tunnel syndrome, tardive dyskinesia due to antipsychotic drugs.

Special Concerns: Safety and effectiveness have not been established in children for doses that exceed the RDA.

Side Effects: CNS: Unstable gait; decreased sensation to touch, temperature, and vibration; paresthesia, sleepiness; numbness of feet; awkwardness of hands; perioral numbness, photoallergic reaction, ataxia. NOTE: Abuse and dependence have been noted in adults administered 200 mg/day.

Overdose Management: Symptoms: Ataxia, severe sensory neuropathy. Treatment: Discontinue pyridoxine; allow up to 6 months for CNS sensation to return.

Drug Interactions: Chloramphenicol / Pyridoxine requirements Contraceptives, oral / Pyridoxine requirements Cycloserine / Pyridoxine requirements Ethionamide / Pyridoxine requirements Hydralazine / Pyridoxine requirements Immunosuppressants / Pyridoxine requirements Isoniazid / Pyridoxine requirements Levodopa / Doses exceeding 5 mg/day pyridoxine antagonize the therapeutic effect of levodopa Penicillamine / Pyridoxine requirements Phenobarbital / Serum phenobarbital levels Phenytoin / Serum phenytoin levels

How Supplied: Enteric coated tablet: 20 mg; Injection: 100 mg/mL; Tablet: 25 mg, 50 mg, 100 mg, 250 mg, 500 mg; Tablet, extended release: 200 mg

Dosage
?Enteric-Coated Tablets, Tablets RDAs.
The RDAs are as follows: Adult males: 1.7-2 mg. Adult females: 1.4-1.6 mg.
Dietary supplement.
Adults: 10-20 mg/day for 2 weeks; then, 2-5 mg/day as part of a multivitamin preparation for several weeks. Pediatric, 2.5-10 mg/day for 3 weeks; then, 2-5 mg/day as part of a multivitamin preparation for several weeks.
Drug-induced deficiency.
Adults, prophylaxis: 6-100 mg/day for isoniazid. Adults, treatment: 50-200 mg/day for 3 weeks followed by 25-100 mg/day to prevent relapse. Adults, alcoholism: 50 mg/day for 2-4 weeks; if anemia responds, continue pyridoxine indefinitely.
?IM, IV Drug-induced deficiency.
Adults: 50-200 mg/day for 3 weeks followed by 25-100 mg/day as needed.
Cycloserine poisoning.
Adults: 300 mg/day.
Isoniazid poisoning.
Adults: 1 g for each gram of isoniazid taken.