pyridoxine (vitamin b6)

Absorption: Well absorbed from the GI tract.

Distribution: Stored in liver, muscle, and brain.

Metabolism/Excretion: Converted in RBCs to pyridoxal phosphate and another active metabolite. Amounts in excess of requirements are excreted unchanged by the kidneys.

Half-Life: 15–20 days.

Time/Action Profile ⬆ ⬇

ROUTE	ONSET	PEAK	DURATION
PO, IM, IV	unknown	unknown	unknown

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity to pyridoxine or any component.

Use Cautiously in:

Parkinson disease (treatment with levodopa only);
OB: Chronic ingestion of large doses may produce pyridoxine-dependency syndrome in newborn.

Adv. Reactions/Side Effects ⬆ ⬇

Adverse reactions listed are seen with excessive doses only.

Neuro: sensory neuropathy, paresthesia

Misc: pyridoxine-dependency syndrome

Interactions ⬆ ⬇

Drug-drug:

Interferes with the therapeutic response to levodopa when used without carbidopa.
Requirements are ↑ by isoniazid, hydralazine, chloramphenicol, penicillamine, estrogens, and immunosuppressants.
May ↓ levels and effectiveness of phenobarbital and phenytoin.

Route/Dosage ⬆ ⬇

Prevention of Deficiency (Recommended Daily Allowance)

PO (Adults and Children >14 yr): 1.2–1.7 mg/day (larger doses required with cycloserine, ethionamide, hydralazine, immunosuppressants, isoniazid, penicillamine, and estrogen-containing oral contraceptives).
PO (Children 9–13 yr): 1 mg/day (larger doses required with cycloserine, ethionamide, hydralazine, immunosuppressants, isoniazid, and penicillamine).
PO (Children 1–8 yr): 0.5–0.6 mg/day (larger doses required with cycloserine, ethionamide, hydralazine, immunosuppressants, isoniazid, and penicillamine).
PO (Infants 6–12 mo): 0.3 mg/day.
PO (Infants <6 mo): 0.1 mg/day.

Treatment of Deficiency

PO (Adults ): 2.5–10 mg/day until clinical signs are corrected, then 2–5 mg/day.
PO (Children ): 5–25 mg/day for 3 wk, then 1.5–2.5 mg/day.

Pyridoxine-Dependent Seizures

PO IM IV (Neonates and Infants): 10–100 mg initially, then 50–100 mg/day orally.

Drug-Induced Neuritis

PO (Adults ): Treatment: 100–300 mg/day; Prophylaxis: 25–100 mg/day.
PO (Children ): Treatment: 10–50 mg/day; Prophylaxis: 1–2 mg/kg/day.

Isoniazid Overdose (>10 g)

IM IV (Adults and Children ): Amount in mg equal to amount of isoniazid ingested given as 1–4 g IV, then 1 g IM every 30 min.

Availability ⬆ ⬇

(Generic available)

Tablets: 10 mg^OTC; 25 mg^OTC; 50 mg^OTC; 100 mg^OTC; 250 mg^OTC
Extended-release tablets: 200 mg^OTC
Oral solution: 12.5 mg/mL
Solution for injection: 100 mg/mL

Assessment ⬆ ⬇

Assess signs/symptoms vitamin B₆ deficiency (anemia, dermatitis, cheilosis, irritability, seizures, nausea, vomiting) before and periodically throughout therapy. Institute seizure precautions in pyridoxine-dependent infants. Pyridoxine-dependent seizures should cease in 2–3 min after IV administration.
Monitor respiratory rate, HR, and BP with large IV dose.

Lab Test Considerations:

May cause false elevations in urobilinogen concentrations.

Implementation ⬆ ⬇

Do not confuse pyridoxine with pralidoxime or Pyridium.
Single B-vitamin deficiencies are infrequent; combination preparations are commonly administered.
- Administration of parenteral vitamin B₆ is indicated for patients who are NPO, have nausea and vomiting, or malabsorption syndromes.
PO: DNC: Swallow extended-release capsules and tablets whole; do not crush, break, or chew. If unable to swallow capsule, the contents may be mixed with jam or jelly.
IM: Rotate sites; burning or stinging at site may occur.
IV: Administer by slow IV push or as infusion in standard IV solutions. Protect parenteral solution from light.
Rate: Infusion rates of 15–30 min and up to 3 hr have been used.
Y-Site Compatibility:
- amikacin
- aminophylline
- ascorbic acid
- atracurium
- atropine
- aztreonam
- benztropine
- bumetanide
- buprenorphine
- butorphanol
- calcium chloride
- calcium gluconate
- cefotaxime
- cefotetan
- cefoxitin
- ceftazidime
- ceftriaxone
- cefuroxime
- chlorpromazine
- clindamycin
- cyanocobalamin
- cyclosporine
- dexamethasone
- digoxin
- diphenhydramine
- dobutamine
- dopamine
- doxycycline
- enalaprilat
- ephedrine
- epinephrine
- epoetin alfa
- erythromycin
- esmolol
- famotidine
- fentanyl
- fluconazole
- gentamicin
- glycopyrrolate
- heparin
- insulin, regular
- isoproterenol
- labetalol
- lidocaine
- magnesium sulfate
- mannitol
- meperidine
- metoclopramide
- metoprolol
- midazolam
- minocycline
- morphine
- multivitamins
- nalbuphine
- naloxone
- nitroglycerin
- nitroprusside
- norepinephrine
- ondansetron
- oxytocin
- papaverine
- penicillin G
- pentamidine
- phentolamine
- phenylephrine
- phytonadione
- potassium chloride
- procainamide
- prochlorperazine
- promethazine
- propranolol
- protamine
- sodium bicarbonate
- succinylcholine
- sufentanil
- theophylline
- thiamine
- tobramycin
- vancomycin
- vasopressin
- verapamil
Y-Site Incompatibility:
- amphotericin B deoxycholate
- azathioprine
- cefazolin
- chloramphenicol
- dantrolene
- diazepam
- diazoxide
- folic acid
- furosemide
- ganciclovir
- hydrocortisone
- imipenem/cilastatin
- indomethacin
- ketorolac
- methylprednisolone
- nafcillin
- oxacillin
- pentobarbital
- phenobarbital
- phenytoin
- trimethoprim/sulfamethoxazole

Patient/Family Teaching ⬆ ⬇

Explain purpose and side effects of medication. Advise patient to read Patient Information before starting therapy.
Encourage patient to comply with diet recommended by health care provider. Explain that the best source of vitamins is a well-balanced diet. Foods high in vitamin B₆ include bananas, whole grains, potatoes, lima beans, and meats.
Caution patient not to exceed RDA for pyridoxine. Large doses may cause unsteady gait, numbness in feet, and difficulty with hand coordination.
Rep: Advise women of reproductive potential to notify health care provider if pregnancy is planned or suspected or if breastfeeding.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇