Drug class: Vitamin B Complex
VA class: VT109
Chemical name: 2-methyl-3-hydroxy-4,5-bis (hydroxymethyl) pyridine hydrochloride
CAS number: 58-56-0

Introduction

Water-soluble, B complex vitamin.

Uses for Pyridoxine

Pyridoxine Deficiency

Treatment of vitamin B₆ deficiency.

Dietary Requirements

Adequate intake needed to prevent vitamin B₆ deficiency.

Adequate intake of pyridoxine can be accomplished through consumption of fortified ready-to-eat cereals; meals containing substantial portions of meat, fish, or poultry; white potatoes and other starchy vegetable; and noncitrus fruits.

Recommended Dietary Allowance (RDA) in adults based on a plasma pyridoxal phosphate concentration of 5 ng/mL.

Adequate intake (AI) established for infants ≤6 months of age based on observed mean vitamin B₆ intake of infants fed principally human milk; AI for infants 7–12 months of age based on AI for younger infants and data in adults.

RDA for children 1–18 years of age based on data in adults.

Pyridoxine-dependent Seizures

Treatment of pyridoxine-dependent seizures.

Metabolic Disorders

Xanthurenic aciduria, cystathioninuria, and homocystinuria resulting from genetic abnormalities may respond to high doses of pyridoxine.

Prevention or Treatment of Drug-induced Neurotoxicity

Prevent or treat neuropathy in patients receiving isoniazid. Pyridoxine prophylaxis recommended in isoniazid-treated individuals with nutritional deficiency (e.g., meat and milk-deficient diet), diabetes mellitus, HIV infection, renal failure, alcoholism, and in exclusively breast-fed infants, pregnant women, and lactating women.

Also has been used to prevent or treat neurotoxic adverse effects (e.g., peripheral neuropathy) associated with ethionamide or capecitabine.

Adjunct for treatment of acute toxicity resulting from isoniazid overdosage.

Mushroom Toxicity

Adjunct for treatment of acute toxicity caused by mushrooms^{† [off-label]} of the genus Gyromitra. Used to correct marked neurologic effects (e.g., seizures, coma) induced by methylhydrazine (produced by hydrolysis of the toxins in these mushrooms).

Pyridoxine Dosage and Administration

Administration

Usually administered orally. May be administered by IM, IV, or sub-Q injection when oral administration is not feasible.

Dosage

Available as pyridoxine hydrochloride; dosage expressed in terms of pyridoxine hydrochloride.

Pediatric Patients

Dietary and Replacement Requirements

Oral

Infants ≤6 months of age: Recommended AI is 0.1 mg (0.01 mg/kg) daily.

Infants 7–12 months of age: Recommended AI is 0.3 mg (0.03 mg/kg) daily.

Children 1–3 years of age: RDA is 0.5 mg daily.

Children 4–8 years of age: RDA is 0.6 mg daily.

Children 9–13 years of age: RDA is 1 mg of daily.

Boys 14–18 years of age: RDA is 1.3 mg daily.

Girls 14–18 years of age: RDA is 1.2 mg daily.

Pyridoxine-dependent Seizures

Oral

Maintenance following parenteral administration: 2–100 mg daily has been recommended.

IM or IV

10–100 mg has been recommended. Follow with lifelong oral pyridoxine.

Adults

Pyridoxine Deficiency

Oral

2.5–10 mg daily.

After clinical signs of deficiency are corrected, administer a multivitamin preparation containing 2–5 mg of pyridoxine hydrochloride once daily for several weeks.

IM or IV

10–20 mg daily for 3 weeks.

Follow with a multivitamin preparation containing 2–5 mg of pyridoxine hydrochloride once daily for several weeks.

Dietary and Replacement Requirements

Oral

Men and women 19–50 years of age: RDA is 1.3 mg daily.

Men ≥51 years of age: RDA is 1.7 mg daily.

Women ≥51 years of age: RDA is 1.5 mg daily.

Prevention of Drug-induced Neurotoxicity

Oral

CDC recommends 25 mg daily for certain isoniazid-treated patients.

Isoniazid Overdose

IV followed by IM

Ingestion of >10 g of isoniazid: Dose of pyridoxine hydrochloride equals the amount of isoniazid ingested.

Initially, 4 g IV; followed by 1 g IM every 30 minutes until the entire dose has been given.

Mushroom Toxicity† [off-label]

IV

25 mg/kg infused over 15–30 minutes and repeated as necessary to control effects up to a maximum cumulative dose of 15–20 g daily has been suggested.

Prescribing Limits

Adults

Long-term (> 2 months) administration of large dosages (≥ 2 g daily) can cause sensory neuropathy or neuronopathy syndromes.

Special Populations

Pregnant Women

RDA for pregnant women is 1.9 mg daily.

Lactating Women

RDA for lactating women is 2 mg daily. Requirements increased in lactating women to ensure adequate concentration of the vitamin in milk (130 ng/mL).

Cautions for Pyridoxine

Contraindications

• Known sensitivity to pyridoxine or any ingredient in the formulation.

• According to one manufacturer, pyridoxine should not be administered IV to patients with heart disease.

Warnings/Precautions

General Precautions

Aluminum Content

Some pyridoxine hydrochloride injection preparations contain aluminum that may be toxic. Aluminum may reach toxic levels with prolonged parenteral administration if kidney function is impaired. Premature neonates are particularly at risk because their kidneys are immature, and they require large amounts of calcium and phosphate solutions, which contain aluminum.

Research indicates that patients with impaired kidney function, including premature neonates, who receive parenteral levels of aluminum >4–5 mcg/kg daily accumulate aluminum at levels associated with CNS and bone toxicity. Tissue loading may occur at even lower rates of administration.

Specific Populations

Pregnancy

Category A.

Lactation

Distributed into milk. Caution if parenteral preparation is used in nursing women.

Pediatric Use

Parenteral preparation: Safety and efficacy not established.

Common Adverse Effects

Usually nontoxic; adverse neurologic effects, nausea, headache, paresthesia, somnolence, increased serum AST, decreased serum folic acid concentrations.

Drug Interactions

For information regarding isoniazid, see Prevention or Treatment of Drug-induced Neurotoxicity under Uses and Prevention of Drug-induced Neurotoxicity and Isoniazid Overdosage under Dosage and Administration.

Specific Drugs and Laboratory Tests

Pyridoxine Pharmacokinetics

Absorption

Bioavailability

Readily absorbed from the GI tract.

Distribution

Extent

Stored mainly in liver with lesser amounts in muscle and brain.

Crosses the placenta; plasma concentrations in the fetus 5 times greater than maternal plasma concentrations. Distributed into milk.

Plasma Protein Binding

Highly protein bound.

Elimination

Metabolism

Metabolized to 4-pyridoxic acid in the liver.

Elimination Route

Metabolite excreted in urine.

Half-life

15-20 days.

Stability

Storage

Oral

Tablets

Well-closed container at <40°C ; maintain at 15–30°C. Protect from light.

Parenteral

Solution

20–25°C. Protect from light.

Actions

• An exogenous source of vitamin B₆ is required for amino acid, carbohydrate, and lipid metabolism.

• Natural substances with vitamin B₆ activity are pyridoxine in plants and pyridoxal and pyridoxamine in animals.

• Pyridoxamine phosphate and pyridoxal phosphate are active forms of the vitamin.

Advice to Patients

• Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs as well as concomitant illness.

• Importance of proper dietary habits, including taking appropriate AI or RDA of vitamin B₆.

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.

• Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

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