thiamine (vitamin b1)

REMS

Treatment of thiamine deficiency (beriberi).
Prevention of Wernicke encephalopathy.
Dietary supplement in patients with GI disease, alcoholism, or cirrhosis.

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Known alcohol intolerance or bisulfite hypersensitivity (elixir only).

Use Cautiously in:

Wernicke encephalopathy (condition may be worsened unless thiamine is administered before glucose).

Adv. Reactions/Side Effects ⬆ ⬇

Adverse reactions and side effects are extremely rare and are usually associated with IV administration or extremely large doses.

CV: hypotension, VASCULAR COLLAPSE

Derm: cyanosis, pruritus, sweating, tingling, urticaria, warmth

EENT: tightness of the throat

GI: nausea

Neuro: restlessness, weakness

Resp: pulmonary edema, respiratory distress

Misc: ANGIOEDEMA

Interactions ⬆ ⬇

Drug-drug:

None reported.

Availability ⬆ ⬇

(Generic available)

Tablets: 50 mg^OTC; 100 mg^OTC; 250 mg^OTC
Oral solution: 25 mg/mL^OTC
Solution for injection: 100 mg/mL

Route/Dosage ⬆ ⬇

Thiamine Deficiency (Beriberi)

PO (Adults ): 5–10 mg 3 times daily.
PO (Children ): 10–50 mg/day in divided doses.
IM IV (Adults ): 5–100 mg 3 times daily.
IM IV (Children ): 10–25 mg/day.

Dietary Supplement

PO (Adults ): 1–1.6 mg/day.
PO (Children 4–10 yr): 0.9–1 mg/day.
PO (Children birth–3 yr): 0.3–0.7 mg/day.

Action ⬆ ⬇

Required for carbohydrate metabolism.

Therapeutic effects:

Replacement in deficiency states.

Classifications ⬆ ⬇

Therapeutic Classification: vitamins

Pharmacologic Classification: water soluble vitamins

Pharmacokinetics ⬆ ⬇

Absorption: Well absorbed from the GI tract by an active process. Excessive amounts are not absorbed completely. Also well absorbed from IM sites.

Distribution: Widely distributed to tissues.

Metabolism/Excretion: Metabolized by the liver. Excess amounts are excreted unchanged by the kidneys.

Half-Life: Unknown.

Time/Action Profile ⬆ ⬇

( time for symptoms of deficiency: edema and HF: to resolve‡)

ROUTE		ONSET		PEAK		DURATION
PO, IM, IV		hr		days		days–wk

‡Confusion and psychosis take longer to respond.

Patient/Family Teaching ⬆ ⬇

Explain purpose and side effects of medication. Advise patient to read Patient Information before starting therapy.
Encourage patient to comply with dietary recommendations. Explain that the best source of vitamins is a well-balanced diet.
Teach that foods high in thiamine include cereals (whole grain and enriched), meats (especially pork), and fresh vegetables.
Caution patient not to exceed RDA for thiamine. Large doses may cause side effects.
Advise patient to notify health care provider of all Rx or OTC medications, vitamins, or herbal products being taken and to consult health care provider before taking other medications.
Rep: Thiamine requirements are ↑ during pregnancy, especially in women with prolonged nausea and vomiting. Advise women of reproductive potential to notify health care provider if pregnancy is planned or suspected or if breastfeeding. RDA for thiamine during lactation is 1.4 mg.

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Indications ⬇