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.^a

Uses for Pyridoxine

Pyridoxine Deficiency

Treatment of vitamin B₆ deficiency.^{a b}

Dietary Requirements

Adequate intake needed to prevent vitamin B₆ deficiency.¹⁵⁷

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.¹⁵⁷

Recommended Dietary Allowance (RDA) in adults based on a plasma pyridoxal phosphate concentration of 5 ng/mL.¹⁵⁷

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.¹⁵⁷

RDA for children 1–18 years of age based on data in adults.¹⁵⁷

Pyridoxine-dependent Seizures

Treatment of pyridoxine-dependent seizures.^{159 a b}

Metabolic Disorders

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

Prevention or Treatment of Drug-induced Neurotoxicity

Prevent or treat neuropathy in patients receiving isoniazid.^{a b} 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.^{c d}

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

Adjunct for treatment of acute toxicity resulting from isoniazid overdosage.^{a b}

Mushroom Toxicity

Adjunct for treatment of acute toxicity caused by mushrooms^{† [off-label]} of the genus Gyromitra.^{153 154 155} Used to correct marked neurologic effects (e.g., seizures, coma) induced by methylhydrazine (produced by hydrolysis of the toxins in these mushrooms).^{153 154 155}

Pyridoxine Dosage and Administration

Administration

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

Dosage

Available as pyridoxine hydrochloride; dosage expressed in terms of pyridoxine hydrochloride.^{a b}

Pediatric Patients

Dietary and Replacement Requirements

Oral

Infants ≤6 months of age: Recommended AI is 0.1 mg (0.01 mg/kg) daily.¹⁵⁷

Infants 7–12 months of age: Recommended AI is 0.3 mg (0.03 mg/kg) daily.¹⁵⁷

Children 1–3 years of age: RDA is 0.5 mg daily.¹⁵⁷

Children 4–8 years of age: RDA is 0.6 mg daily.¹⁵⁷

Children 9–13 years of age: RDA is 1 mg of daily.¹⁵⁷

Boys 14–18 years of age: RDA is 1.3 mg daily.¹⁵⁷

Girls 14–18 years of age: RDA is 1.2 mg daily.¹⁵⁷

Pyridoxine-dependent Seizures

Oral

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

IM or IV

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

Adults

Pyridoxine Deficiency

Oral

2.5–10 mg daily.^a

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

IM or IV

10–20 mg daily for 3 weeks.^b

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

Dietary and Replacement Requirements

Oral

Men and women 19–50 years of age: RDA is 1.3 mg daily.¹⁵⁷

Men ≥51 years of age: RDA is 1.7 mg daily.¹⁵⁷

Women ≥51 years of age: RDA is 1.5 mg daily.¹⁵⁷

Prevention of Drug-induced Neurotoxicity

Oral

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

Isoniazid Overdose

IV followed by IM

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

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

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.^{153 154 155}

Prescribing Limits

Adults

Long-term (> 2 months) administration of large dosages (≥ 2 g daily) can cause sensory neuropathy or neuronopathy syndromes.^{115 120 123}

Special Populations

Pregnant Women

RDA for pregnant women is 1.9 mg daily.¹⁵⁷

Lactating Women

RDA for lactating women is 2 mg daily.¹⁵⁷ Requirements increased in lactating women to ensure adequate concentration of the vitamin in milk (130 ng/mL).¹⁵⁷

Cautions for Pyridoxine

Contraindications

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

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

Warnings/Precautions

General Precautions

Aluminum Content

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

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.^b Tissue loading may occur at even lower rates of administration.^b

Specific Populations

Pregnancy

Category A.^b

Lactation

Distributed into milk.¹⁵⁷ Caution if parenteral preparation is used in nursing women.^b

Pediatric Use

Parenteral preparation: Safety and efficacy not established.^b

Common Adverse Effects

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

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.^a

Distribution

Extent

Stored mainly in liver with lesser amounts in muscle and brain.¹⁵⁷

Crosses the placenta; plasma concentrations in the fetus 5 times greater than maternal plasma concentrations.^a Distributed into milk.¹⁵⁷

Plasma Protein Binding

Highly protein bound.^a

Elimination

Metabolism

Metabolized to 4-pyridoxic acid in the liver.^b

Elimination Route

Metabolite excreted in urine.^b

Half-life

15-20 days.^b

Stability

Storage

Oral

Tablets

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

Parenteral

Solution

20–25°C. ^b Protect from light.^b

Actions

• An exogenous source of vitamin B₆ is required for amino acid, carbohydrate, and lipid metabolism.^{a b}

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

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

Advice to Patients

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

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

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

• Importance of informing patients of other important precautionary information.^a (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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