thiamine (Rx, OTC)

Frequency Not Defined

Warmth

Anaphylaxis

Cyanosis

Diaphoresis

Restlessness

Angioneurotic edema

Pruritus

Urticaria

Pulmonary edema

Weakness

Tightness of the throat

Nausea

Contraindications

Hypersensitivity

Cautions

In pregnancy (doses >RDA)

Acute thiamine deficiency reported with dextrose administration; use caution when thiamine status uncertain

Hypersensitivity reactions reported following repeated parenteral doses

Parenteral products may contain aluminum; use caution in patients with impaired renal function

Evaluate for additional vitamin deficiencies if patient diagnosed with thiamin deficiency; single vitamin deficiencies are rare

Pregnancy Category: A (injectable); C (if >RDA)

Lactation: Safe

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

Sources: brewer's yeast, pork, ham, liver, whole grains, peas, beans, milk

Function: cofactor in glucose metabolism

Deficiency: (common in alcoholics, Asians, dialysis patients, those on high carbohydrate diet) Beriberi; causes nerve damage, dementia, heart failure; sometimes irreversible

Reduced/Destroyed by

Heat-labile thiaminases contained in milled rice, raw shellfish & freshwater fishes

Heat-stable anti-thiamine factor in coffee/tea

Sulfite-containing foods

Alcohol

High temp

Toxicity Symptoms

Toxicity: rare; intake of >400 mg/d; lethargy, balance problems, intestinal problems

Mechanism of Action

Forms thiamine pyrophosphate by combining with adenosine triphosphate; essential coenzyme in carbohydrate metabolism

Pharmacokinetics

Distribution: Distributes mainly to heart, brain, kidney, and liver

Excretion: Urine

Absorption: Adequate (PO); rapid and complete (IM)

When oral administration is not feasible

When malabsorption is suspected

In patients with Wernicke's encephalopathy or high-output heart failure secondary to beriberi

IV administration preferred for high-output heart failure

Compatible with most common diluents (dextrose solutions; LR, Ringer's; dextrose-saline solutions; dextrose/LR; NS; ½NS; fat emulsion 10%; Na-lactate 1M/6