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.^a

Uses for Thiamine

Thiamine Deficiency

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

Dietary Requirements

Adequate intake needed to prevent thiamine deficiency (beriberi).¹⁰⁹

Adequate thiamine intake can be accomplished through consumption of foodstuffs.¹⁰⁹ 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.¹⁰⁹

Recommended Dietary Allowance (RDA) in adults based on erythrocyte transketolase activity, urinary thiamine excretion, and other findings.¹⁰⁹

Requirements slightly lower in women than men based on women's size and average energy utilization.¹⁰⁹

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.¹⁰⁹

RDA for children 1–18 years of age based on data in adults.¹⁰⁹

Metabolic Disorder

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

Thiamine Dosage and Administration

Administration

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

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

Dosage

Available as thiamine hydrochloride; dosage expressed in terms of the salt.^{a b}

Pediatric Patients

Thiamine Deficiency

Oral

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

IM or IV

Critically ill children (e.g., infantile beriberi): 10–25 mg.^{a b}

Dietary and Replacement Requirements

Oral

Infants ≤6 months of age: Recommended AI is 0.2 mg (0.03 mg/kg) daily.¹⁰⁹

Infants 7–12 months of age: Recommended AI is 0.3 mg (0.03 mg/kg) daily.¹⁰⁹

Children 1–3 years of age: RDA is 0.5 mg daily.¹⁰⁹

Children 4–8 years of age: RDA is 0.6 mg daily.¹⁰⁹

Children 9–13 years of age: RDA is 0.9 mg daily.¹⁰⁹

Boys 14–18 years of age: RDA is 1.2 mg daily.¹⁰⁹

Girls 14–18 years of age: RDA is 1 mg daily.¹⁰⁹

RDAs not expected to meet the needs of those with malabsorption syndrome or undergoing hemodialysis or peritoneal dialysis.¹⁰⁹

Adults

Thiamine Deficiency

Oral

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

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.^b

IV or IM

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

IM

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

Dietary and Replacement Requirements

Oral

Men ≥19 years of age: RDA is 1.2 mg daily.¹⁰⁹

Women ≥19 years of age: RDA is 1.1 mg daily.¹⁰⁹

RDAs not expected to meet the needs of those with malabsorption syndrome or undergoing hemodialysis or peritoneal dialysis.¹⁰⁹

Prescribing Limits

Single doses >30 mg not likely to be utilized.^a

Special Populations

Pregnant Women

RDA for pregnant women is 1.4 mg daily.¹⁰⁹

Thiamine intake >1.4 mg daily needed by women who are pregnant with >1 fetus.¹⁰⁹

Requirements increased in pregnant women to cover increased energy utilization and growth in the maternal and fetal compartments.¹⁰⁹

Lactating Women

RDA for lactating women is 1.5 mg daily.¹⁰⁹

Thiamine intake >1.5 mg daily needed by women who are nursing >1 infant.¹⁰⁹

Requirements increased in lactating women to ensure adequate concentration of the vitamin in milk.¹⁰⁹

Cautions for Thiamine

Contraindications

Known sensitivity to thiamine or any ingredient in formulation.^{a b}

Warnings/Precautions

Sensitivity Reactions

Hypersensitivity Reactions

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

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.^b

General Precautions

Aluminum Content

Some thiamine hydrochloride injection preparations contain aluminum, which 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 aluminum parenterally in quantities of >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.^a Caution if parenteral preparation is used in nursing women.^b

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.^{a b}

Drug Interactions

Specific Drugs and Laboratory Tests

Thiamine Pharmacokinetics

Absorption

Bioavailability

Small doses are readily absorbed from the GI tract.^a

Completely absorbed following IM administration.^b

Food

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

Distribution

Extent

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

Elimination

Elimination Route

Excreted in urine as unchanged drug and metabolites.^a

Stability

Storage

Oral

Tablets

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

Parenteral

Injection

20–25°C.^b Protect from light.^b

Compatibility

Parenteral

Solution CompatibilityHID

Drug Compatibility

Actions

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

• Functions as a coenzyme in the metabolism of carbohydrates and branched-chain amino acids.¹⁰⁹

Advice to Patients

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

• Importance of proper dietary habits, including taking appropriate AI or RDA of thiamine.¹⁰⁹

• 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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