Drug class: Vitamin B Complex
VA class: VT105
Chemical name: thiazolium,3- [(4-amino-2-methyl-5-pyrimidinyl)methyl]-5-(2-hydroxyethyl)-4-methyl-chloride, monochloride
CAS number: 67-03-8

Introduction

Water-soluble, B complex vitamin.

Uses for Thiamine

Thiamine Deficiency

Treatment of thiamine deficiency syndromes (e.g., beriberi, Wernicke’s encephalopathy syndrome).

Dietary Requirements

Adequate intake needed to prevent thiamine deficiency (beriberi).

Adequate thiamine intake can be accomplished through consumption of foodstuffs. Enriched, fortified, or whole grain products; bread and bread products; mixed foods with grain as a main ingredient; and ready-to-eat cereals are the major contributors of thiamine in the diet of US adults and children.

Recommended Dietary Allowance (RDA) in adults based on erythrocyte transketolase activity, urinary thiamine excretion, and other findings.

Requirements slightly lower in women than men based on women's size and average energy utilization.

Adequate intake (AI) established for infants ≤6 months of age based on observed mean thiamine 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.

Metabolic Disorder

Has been used in thiamine-responsive maple syrup urine disease^{† [off-label]} and subacute necrotizing encephalomyelopathy^{† [off-label]} (Leigh's disease).

Thiamine Dosage and Administration

Administration

Usually administered orally. May be administered by IV or IM injection when indicated or when oral administration is not feasible.

For solution and drug compatibility information, see Compatibility under Stability.

Dosage

Available as thiamine hydrochloride; dosage expressed in terms of the salt.

Pediatric Patients

Thiamine Deficiency

Oral

Noncritically ill children: 10–50 mg daily, given in divided doses.

IM or IV

Critically ill children (e.g., infantile beriberi): 10–25 mg.

Dietary and Replacement Requirements

Oral

Infants ≤6 months of age: Recommended AI is 0.2 mg (0.03 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 0.9 mg daily.

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

Girls 14–18 years of age: RDA is 1 mg daily.

RDAs not expected to meet the needs of those with malabsorption syndrome or undergoing hemodialysis or peritoneal dialysis.

Adults

Thiamine Deficiency

Oral

Noncritically ill adults: 5–30 mg daily, as a single dose or 3 divided doses, for 1 month.

IV followed by IM

Wernicke's syndrome: Initially 100 mg IV, followed by 50–100 mg IM daily until patient can consume a balanced diet.

IV or IM

Critically ill thiamine-deficient adult or patient with malabsorption syndrome: 5–100 mg 3 times daily.

IM

Beriberi: 10–20 mg 3 times daily for up to 2 weeks.

Dietary and Replacement Requirements

Oral

Men ≥19 years of age: RDA is 1.2 mg daily.

Women ≥19 years of age: RDA is 1.1 mg daily.

RDAs not expected to meet the needs of those with malabsorption syndrome or undergoing hemodialysis or peritoneal dialysis.

Prescribing Limits

Single doses >30 mg not likely to be utilized.

Special Populations

Pregnant Women

RDA for pregnant women is 1.4 mg daily.

Thiamine intake >1.4 mg daily needed by women who are pregnant with >1 fetus.

Requirements increased in pregnant women to cover increased energy utilization and growth in the maternal and fetal compartments.

Lactating Women

RDA for lactating women is 1.5 mg daily.

Thiamine intake >1.5 mg daily needed by women who are nursing >1 infant.

Requirements increased in lactating women to ensure adequate concentration of the vitamin in milk.

Cautions for Thiamine

Contraindications

Known sensitivity to thiamine or any ingredient in formulation.

Warnings/Precautions

Sensitivity Reactions

Hypersensitivity Reactions

Possible severe hypersensitivity reactions/anaphylaxis, especially following repeated parenteral administration.

Skin Test

Administer an intradermal test dose prior to parenteral administration of therapeutic doses of thiamine in patients who may be sensitive to the drug.

General Precautions

Aluminum Content

Some thiamine hydrochloride injection preparations contain aluminum, which 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 aluminum parenterally in quantities of >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.

Common Adverse Effects

Relatively nontoxic; feelings of warmth, pruritus, urticaria, weakness, sweating, nausea, restlessness, angioedema, tightness in the throat, cyanosis, pulmonary edema, GI bleeding reported with parenteral administration.

Drug Interactions

Specific Drugs and Laboratory Tests

Thiamine Pharmacokinetics

Absorption

Bioavailability

Small doses are readily absorbed from the GI tract.

Completely absorbed following IM administration.

Food

Rate, but not extent, of GI absorption is decreased when administered with meals.

Distribution

Extent

Distributed into all tissues; highest concentrations in liver, brain, kidney, and heart.

Elimination

Elimination Route

Excreted in urine as unchanged drug and metabolites.

Stability

Storage

Oral

Tablets

Tight, light-resistant container at <40°C; preferably between 15–30°C.

Parenteral

Injection

20–25°C. Protect from light.

Compatibility

Parenteral

Solution CompatibilityHID

Drug Compatibility

Actions

• An exogenous source of thiamine is required for carbohydrate metabolism.

• Functions as a coenzyme in the metabolism of carbohydrates and branched-chain amino acids.

Advice to Patients

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

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

• 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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