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Pyridoxine

Pronunciation

Pronunciation

(peer i DOKS een)

Index Terms

  • B6
  • B6
  • Pyridoxine HCl
  • Pyridoxine Hydrochloride
  • Vitamin B6

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Capsule, Oral, as hydrochloride:

Neuro-K-250 T.D.: 250 mg [corn free, rye free, starch free, sugar free, wheat free]

Solution, Injection, as hydrochloride:

Generic: 100 mg/mL (1 mL)

Tablet, Oral, as hydrochloride:

Neuro-K-50: 50 mg

Neuro-K-500: 500 mg

Neuro-K-250 Vitamin B6: 250 mg

Pyri 500: 500 mg

Generic: 25 mg, 50 mg, 100 mg, 250 mg

Tablet, Oral, as hydrochloride [preservative free]:

Generic: 25 mg, 50 mg, 100 mg

Tablet Extended Release, Oral, as hydrochloride:

Generic: 200 mg

Brand Names: U.S.

  • Neuro-K-250 T.D. [OTC]
  • Neuro-K-250 Vitamin B6 [OTC]
  • Neuro-K-50 [OTC]
  • Neuro-K-500 [OTC]
  • Pyri 500 [OTC]

Pharmacologic Category

  • Vitamin, Water Soluble

Pharmacology

Precursor to pyridoxal, which functions in the metabolism of proteins, carbohydrates, and fats; pyridoxal also aids in the release of liver and muscle-stored glycogen and in the synthesis of GABA (within the central nervous system) and heme

Absorption

Well absorbed (IOM 1998)

Metabolism

Hepatic to pyridoxal phosphate and pyridoxamine phosphate (active forms)

Excretion

Urine (as metabolites)

Half-Life Elimination

Biologic: 15 to 20 days

Use: Labeled Indications

Pyridoxine deficiency: Treatment and prevention of pyridoxine (vitamin B6) deficiency.

Contraindications

Hypersensitivity to pyridoxine or any component of the formulation

Dosing: Adult

Recommended daily allowance (RDA): Oral (IOM 1998):

19 to 50 years: 1.3 mg

≥51 years:

Females: 1.5 mg

Males: 1.7 mg

Pregnancy: 1.9 mg

Lactation: 2 mg

Pyridoxine deficiency: IM, IV: 10 to 20 mg/day for 3 weeks, followed by daily oral therapy for several weeks. Doses up to 600 mg/day may be needed with pyridoxine dependency syndrome.

Gyromitrin-containing mushroom (false morel) overdose/toxicity (treatment/prophylaxis) (off-label use): IV: 25 mg/kg over 15 to 30 minutes; repeat dose as needed to control seizures (Diaz 2005; Lheureux 2005)

Nausea and vomiting of pregnancy (off-label use): Oral: 10 to 25 mg every 8 hours (Neibyl 2010).

Neurological toxicities (ie, seizures, coma) associated with isoniazid overdose (prevention) (off-label use): IV: Asymptomatic patients who present within 2 hours of ingesting a potentially toxic amount of isoniazid should receive a prophylactic dose of pyridoxine (Hernon 2015). Dosing recommendations are the same as for the treatment of symptomatic patients.

Neurological toxicities (ie, seizures, coma) associated with isoniazid overdose (treatment) (off-label use): IV:

Acute ingestion of known amount: Initial: A total dose of pyridoxine equal to the amount of isoniazid ingested (maximum dose: 5 g); administer at a rate of 0.5 to 1 g/minute until seizures stop or the maximum initial dose has been administered; may repeat every 5 to 10 minutes as needed to control persistent seizure activity and/or CNS toxicity. If seizures stop prior to the administration of the calculated initial dose, infuse the remaining pyridoxine over 4 to 6 hours (Howland 2015; Morrow 2006).

Acute ingestion of unknown amount: Initial: 5 g; administer at a rate of 0.5 to 1 g/minute; may repeat every 5 to 10 minutes as needed to control persistent seizure activity and/or CNS toxicity (Howland 2015; Morrow 2006).

Peripheral neuropathy associated with isoniazid therapy for Mycobacterium tuberculosis (prevention): Oral: 25 to 50 mg/day (CDC [Kaplan 2009]).

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Adequate Intake (AI): Oral (IOM 1998): Infants:

1 to 6 months: 0.1 mg/day

7 to 12 months: 0.3 mg/day

Recommended daily allowance (RDA): Oral (IOM 1998): Children and Adolescents:

1 to 3 years: 0.5 mg

4 to 8 years: 0.6 mg

9 to 13 years: 1 mg

14 to 18 years:

Females: 1.2 mg

Males: 1.3 mg

Gyromitrin-containing mushroom (false morel) overdose/toxicity (treatment/prophylaxis) (off-label use): IV: Children and Adolescents: Refer to adult dosing.

Neurological toxicities (ie, seizures, coma) associated with isoniazid overdose (prevention) (off-label use): IV: Children and Adolescents: Refer to adult dosing.

Neurological toxicities (ie, seizures, coma) associated with isoniazid overdose (treatment) (off-label use): IV: Children and Adolescents:

Acute ingestion of known amount: Initial: A total dose of pyridoxine equal to the amount of isoniazid ingested (maximum dose: 70 mg/kg, up to 5 g); administer at a rate of 0.5 to 1 g/minute until seizures stop or the maximum initial dose has been administered; may repeat every 5 to 10 minutes as needed to control persistent seizure activity and/or CNS toxicity. If seizures stop prior to the administration of the calculated initial dose, infuse the remaining pyridoxine over 4 to 6 hours (Howland 2015; Morrow 2006).

Acute ingestion of unknown amount: Initial: 70 mg/kg (maximum dose: 5 g); administer at a rate of 0.5 to 1 g/minute; may repeat every 5 to 10 minutes as needed to control persistent seizure activity and/or CNS toxicity (Howland 2015; Morrow 2006; Santucci 1999)

Dosing: Renal Impairment

There are no dosage adjustments provided in the manufacturer’s labeling.

Dosing: Hepatic Impairment

There are no dosage adjustments provided in the manufacturer’s labeling.

Extemporaneously Prepared

A 1 mg/mL oral solution may be made using pyridoxine injection. Withdraw 100 mg (1 mL of a 100 mg/mL injection) from a vial with a needle and syringe; add to 99 mL simple syrup in an amber bottle. Label "refrigerate". Stable for 30 days refrigerated.

Nahata MC, Pai VB, and Hipple TF, Pediatric Drug Formulations, 5th ed, Cincinnati, OH: Harvey Whitney Books Co, 2004.

Administration

Injection: Administer IM or IV.

Gyromitrin-containing mushroom (false morel) overdose/toxicity (treatment/prophylaxis) (off-label use): Administer dose over 15 to 30 minutes (Lheureux 2005).

Isoniazid toxicity (off-label use): Initial doses should be administered at a rate of 0.5 to 1 g/minute. If the parenteral formulation is not available, anecdotal reports suggest that pyridoxine tablets may be crushed and made into a slurry and given at the same dose orally or via nasogastric (NG) tube (Hernon 2015). Oral administration is not recommended for acutely poisoned patients with seizure activity.

Compatibility

Stable in fat emulsion 10%.

Storage

Injection: Store at 20°C to 25°C (68°F to 77°F). Protect from light.

Oral: Store at room temperature. Avoid excessive heat or moisture.

Drug Interactions

Altretamine: Pyridoxine may diminish the therapeutic effect of Altretamine. Specifically when altretamine is used in combination with Cisplatin the response duration may be diminished. Consider therapy modification

Barbiturates: Pyridoxine may increase the metabolism of Barbiturates. Apparent in high pyridoxine doses (eg, 200 mg/day) Monitor therapy

Fosphenytoin: Pyridoxine may increase the metabolism of Fosphenytoin. This is most apparent in high pyridoxine doses (e.g., 80 mg to 200 mg daily) Monitor therapy

Levodopa: Pyridoxine may diminish the therapeutic effect of Levodopa. Management: The concomitant use of pyridoxine and levodopa (in the absence of a dopa decarboxylase inhibitor (DDI)) should be avoided. Use of a DDI (e.g., carbidopa) with levodopa will essentially eliminate the risk of this interaction. Consider therapy modification

Phenytoin: Pyridoxine may increase the metabolism of Phenytoin. This is most apparent in high pyridoxine doses (e.g., 80 mg to 200 mg daily) Monitor therapy

Adverse Reactions

Frequency not defined.

Central nervous system: Ataxia, drowsiness, headache, neuropathy, paresthesia, seizure (following very large IV doses)

Endocrine & metabolic: Acidosis, folate deficiency

Gastrointestinal: Nausea

Hepatic: Increased serum AST

Hypersensitivity: Hypersensitivity reaction

Warnings/Precautions

Concerns related to adverse effects:

• Neuropathy: Severe, permanent peripheral neuropathies have been reported; neurotoxicity is more common with long-term administration of large doses (>2 g/day) (Albin 1987).

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Dosage form specific issues:

• Aluminum: The parenteral product may contain aluminum; toxic aluminum concentrations may be seen with high doses, prolonged use, or renal impairment. Premature neonates are at higher risk due to immature renal function and aluminum intake from other parenteral sources. Parenteral aluminum exposure of >4 to 5 mcg/kg/day is associated with CNS and bone toxicity; tissue loading may occur at lower doses (Federal Register 2002). See manufacturer’s labeling.

Other warnings/precautions:

• Dependence/withdrawal: Doses >200 mg/day may cause dependence and withdrawal.

• Pharmacy supply of emergency antidotes: Guidelines suggest that at least 8 to 24 g be stocked. This is enough to treat 1 patient weighing 100 kg for an initial 8- to 24-hour period. In areas where tuberculosis is common and isoniazid toxicity is more likely, hospitals should consider stocking 24 g. This is enough to treat 1 patient for 24 hours (Dart 2009).

• Vitamin deficiency: Single vitamin deficiency is rare; evaluate for other deficiencies.

Monitoring Parameters

For treatment of isoniazid or gyromitrin-containing mushroom toxicity: Anion gap, arterial blood gases, electrolytes, neurological exam, seizure activity

Pregnancy Risk Factor

A

Pregnancy Considerations

Water soluble vitamins cross the placenta. Maternal pyridoxine plasma concentrations may decrease as pregnancy progresses and requirements may be increased in pregnant women (IOM 1998). Pyridoxine is used to treat nausea and vomiting of pregnancy (Neibyl 2010). In general, medications used as antidotes should take into consideration the health and prognosis of the mother; antidotes should be administered to pregnant women if there is a clear indication for use and should not be withheld because of fears of teratogenicity (Bailey 2003).

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Have patient report immediately to prescriber burning or numbness feeling (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

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