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  • CLASSES

    Calcium Supplements in Combination with Other Agents
    Thiamine/Vitamin B1 Supplements

    DEA CLASS

    Rx, OTC

    DESCRIPTION

    Water-soluble vitamin; found in yeast, cereal grains, legumes, peas, nuts, pork, and beef; deficiency causes beriberi; considered a standard agent in the treatment of a patient with undiagnosed coma and to prevent Wernicke/Korsakoff syndrome.

    HOW SUPPLIED

    Thiamine (Vitamin B1)/Thiamine Hydrochloride (Vitamin B1) Intramuscular Inj Sol: 1mL, 100mg
    Thiamine (Vitamin B1)/Thiamine Hydrochloride (Vitamin B1) Intravenous Inj Sol: 1mL, 100mg

    DOSAGE & INDICATIONS

    For nutritional supplementation.
    For the recommended dietary allowance (RDA) of thiamine for nutritional supplementation in healthy individuals.
    Oral dosage
    Adult and Adolescent pregnant or lactating females

    1.4 mg PO per day.

    Adult and Adolescent males >= 14 years

    1.2 mg PO per day.

    Adult females >= 19 years

    1.1 mg PO per day.

    Adolescent females >= 14 years

    1 mg PO per day.

    Children 9—13 years

    0.9 mg PO per day.

    Children 4—8 years

    0.6 mg PO per day.

    Children 1—3 years

    0.5 mg PO per day.

    Infants 7—12 months

    0.3 mg PO per day is the Adequate Intake (AI). An RDA has not been established.

    Infants 0—6 months

    0.2 mg/day PO is the Adequate Intake (AI). An RDA has not been established.

    To prevent thiamine deficiency in patients receiving total parenteral nutrition (TPN).
    Intravenous dosage
    Adults

    3 mg IV per day admixed with TPN.

    For the treatment of beriberi.
    NOTE: If beriberi occurs in a breast-fed infant, both the lactating mother and the infant should receive treatment for thiamine deficiency.
    Oral dosage (beriberi in non-critically ill patients)
    Adults

    5—30 mg PO once daily or given in 3 divided doses for 1 month.

    Infants and Children

    10—50 mg PO once daily for 2 weeks, then 5—10 mg PO once daily for 1 month.

    Intravenous or Intramuscular dosage (severe beriberi or patients with malabsorption syndromes)

    NOTE: Some clinicians prefer IV administration when beriberi is accompanied by high-output heart failure.

    Adults

    5—30 mg IV or IM once daily or in 3 divided doses initially; then convert to 5—30 mg PO once daily or in 3 divided doses once patient is taking PO. Total treatment duration is 1 month.

    Infants and Children

    10—25 mg IV or IM per day for 2 weeks, then 5—10 mg PO once daily for 1 month.

    For the treatment of Wernicke/Korsakoff syndrome.
    NOTE: Intravenous glucose loading may aggravate the symptoms of Wernicke's encephalopathy in some thiamine-deficient patients. Thiamine should be administered prior to glucose.
    Intravenous or Intramuscular dosage
    Adults

    Initially, 100 mg IV, followed by 50—100 mg IM daily until normal dietary intake is established. Clinical practice guidelines recommend 200—500 mg IV or IM three times daily for 5—7 days or until there is no further improvement in symptoms. Initiate treatment with 500 mg IV or IM three times daily in alcoholic patients. Intravenous administration is preferred.

    For the treatment of metabolic disorders including necrotizing encephalomyelopathy, maple syrup urine disease (MSUD), and lactic acidosis associated with pyruvate carboxylase deficiency.
    Oral dosage
    Adults

    10—20 mg/day PO as a single dose. Up to 4 g/day in divided doses has been used.

    MAXIMUM DOSAGE

    Upper tolerable intake levels in healthy, non-vitamin deficient individuals are not determinable due to a lack of data.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    It appears that no dosage adjustments are needed.

    Renal Impairment

    It appears that no dosage adjustments are needed.
     
    Intermittent hemodialysis
    Patients on dialysis may have increased needs for thiamine.
     
    Peritoneal dialysis
    Patients on dialysis may have increased needs for thiamine.

    ADMINISTRATION

    Oral Administration

    Thiamine, vitamin B1 may be administered without regard to meals.

    Injectable Administration

    Administer intramuscularly or intravenously. Parenteral therapy is usually reserved for patients for which oral thiamine is not feasible.
    Prior to intravenous administration, an intradermal test dose should be administered to patients in whom a sensitivity might be suspected.
    Visually inspect parenteral products for particulate matter and discoloration prior to administration whenever solution and container permit.

    Intravenous Administration

    Direct IV injection:
    No dilution is necessary.
    Inject each 100 mg thiamine, vitamin B1 via slow IV push.
     
    Continuous IV infusion:
    Dilute thiamine, vitamin B1 in a compatible infusion solution.
    Administer at a rate prescribed by the physician.

    Intramuscular Administration

    Inject thiamine, vitamin B1 deeply into a large muscle.
    Tenderness and induration may occur at the injection site. Discomfort may be reduced by applying cool compresses.

    STORAGE

    Generic:
    - Store at room temperature (between 59 to 86 degrees F)

    CONTRAINDICATIONS / PRECAUTIONS

    Encephalopathy

    Wernicke's encephalopathy may be precipitated or worsened if intravenous glucose is administered to a thiamine-deficient patient. Thiamine (vitamin B1) should be administered prior to glucose. Clinicians should note that parenteral glucose should never be administered to a comatose patient without the prior administration of thiamine.

    Pregnancy

    Thiamine is classified as FDA pregnancy risk category A. Appropriate maternal thiamine (vitamin B1) intake is encouraged during pregnancy, and no maternal or fetal complications associated with maternal dietary intake or supplementation to achieve adequate intake goals have been reported. As with other water-soluble vitamins, the pregnancy risk factor increases to FDA risk category C if the vitamin is used in dosages exceeding the Recommended Dietary Allowance (RDA) during pregnancy.

    Breast-feeding

    According to the manufacturer, caution should be exercised when thiamine is administered during breast-feeding. However, while thiamine is excreted in human milk, appropriate maternal intake of thiamine (vitamin B1) is important during lactation, and no maternal or fetal complications have been identified with maternal supplementation to achieve adequate intake goals during breast-feeding. Seizures have occurred in nursing infants of mothers with thiamine deficiency, although causality has not been established. Supplementation with thiamine is recommended in lactating women whose diets do not provide adequate amounts of thiamine. The American Academy of Pediatrics classifies thiamine as compatible with breast-feeding. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, healthcare providers are encouraged to report the adverse effect to the FDA.

    ADVERSE REACTIONS

    Severe

    angioedema / Rapid / Incidence not known
    anaphylactoid reactions / Rapid / Incidence not known
    pulmonary edema / Early / Incidence not known
    GI bleeding / Delayed / Incidence not known
    cyanosis / Early / Incidence not known

    Mild

    pruritus / Rapid / 1.0-1.0
    restlessness / Early / Incidence not known
    diaphoresis / Early / Incidence not known
    sneezing / Early / Incidence not known
    urticaria / Rapid / Incidence not known
    nausea / Early / Incidence not known
    weakness / Early / Incidence not known
    injection site reaction / Rapid / Incidence not known

    DRUG INTERACTIONS

    There are no drug interactions associated with Thiamine, Vitamin B1 products.

    PREGNANCY AND LACTATION

    Pregnancy

    Thiamine is classified as FDA pregnancy risk category A. Appropriate maternal thiamine (vitamin B1) intake is encouraged during pregnancy, and no maternal or fetal complications associated with maternal dietary intake or supplementation to achieve adequate intake goals have been reported. As with other water-soluble vitamins, the pregnancy risk factor increases to FDA risk category C if the vitamin is used in dosages exceeding the Recommended Dietary Allowance (RDA) during pregnancy.

    According to the manufacturer, caution should be exercised when thiamine is administered during breast-feeding. However, while thiamine is excreted in human milk, appropriate maternal intake of thiamine (vitamin B1) is important during lactation, and no maternal or fetal complications have been identified with maternal supplementation to achieve adequate intake goals during breast-feeding. Seizures have occurred in nursing infants of mothers with thiamine deficiency, although causality has not been established. Supplementation with thiamine is recommended in lactating women whose diets do not provide adequate amounts of thiamine. The American Academy of Pediatrics classifies thiamine as compatible with breast-feeding. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, healthcare providers are encouraged to report the adverse effect to the FDA.

    MECHANISM OF ACTION

    Mechanism of Action: Thiamine combines with adenosine triphosphate (ATP) in the liver, kidneys, and leukocytes to produce thiamine diphosphate. Thiamine diphosphate acts as a coenzyme in carbohydrate metabolism, in transketolation reactions, and in the utilization of hexose in the hexose-monophosphate shunt. Without adequate thiamine, pyruvic acid does not undergo conversion to acetyl-CoA and cannot enter the Krebs cycle. Pyruvic acid accumulates in the blood and is subsequently converted to lactic acid, with the potential development of lactic acidosis. Diminished production of NADH in the Krebs cycle also results in lactic acid production through facilitation of anaerobic glycolysis.Thiamine deficiency appears as a nonspecific syndrome: headache, nausea, malaise, myalgias. Severe thiamine deficiency causes beriberi. Beriberi can affect the cardiovascular system (wet beriberi) and the nervous system (dry beriberi and the Wernicke-Korsakoff syndrome). Cardiovascular manifestations include peripheral vasodilation, biventricular failure, and edema. Neurologic symptoms include neuropathy, ataxia, retrograde amnesia, impaired ability to learn, and confabulation. Once Korsakoff's syndrome appears, thiamine supplementation is successful in only half of the patients.

    PHARMACOKINETICS

    Thiamine is administered orally and by intramuscular or intravenous injection.  Thiamine is widely distributed. Body storage of thiamine is limited to about 30 mg. Thiamine is distributed into breast milk at a rate of about 100—200 mcg daily from normal dietary intake. There is little excretion of thiamine or its metabolites at physiologic doses. Following large doses, saturation occurs, with subsequent renal excretion as pyrimidine.

    Oral Route

    Small oral doses are readily absorbed from the GI tract, but absorption of large doses is limited. Administration with food reduces the rate of absorption.

    Intramuscular Route

    Following IM administration of thiamine, vitamin B1, absorption is rapid and complete.