Pharmacology. Thiamine (vitamin B1) is a water-soluble vitamin that acts as an essential cofactor for various pathways of carbohydrate metabolism. Thiamine also acts as a cofactor in the metabolism of glyoxylic acid (produced in ethylene glycol intoxication). Thiamine deficiency may result in beriberi and Wernicke-Korsakoff syndrome. Thiamine is absorbed rapidly after oral, intramuscular, or intravenous administration. However, parenteral administration is recommended for initial management of thiamine deficiency syndromes.
Empiric therapy to prevent and treat Wernicke-Korsakoff syndrome in alcoholic or malnourished patients. This includes any patient presenting with an altered mental status of unknown etiology. Thiamine should be given concurrently with glucose in such cases.
Adjunctive treatment in patients poisoned with ethylene glycol to possibly enhance the detoxification of glyoxylic acid.
Contraindications. Use caution in patients with known sensitivity to thiamine or preservatives.
Anaphylactoid reactions, vasodilation, hypotension, weakness, and angioedema after rapid intravenous injection. These may be attributable to the vehicle or contaminants of thiamine preparations in the past; rare reaction with new preparations.
Acute pulmonary edema in patients with beriberi owing to a sudden increase in vascular resistance.
Use in pregnancy. FDA Category A for doses up to the recommended daily allowance (RDA) and Category C for pharmacologic doses (See Introduction in Section III).
Drug or laboratory interactions. Theoretically, thiamine may enhance the effect of neuromuscular blockers, although the clinical significance is unclear.
Dosage and method of administration. Parenteral, 100 mg (children: 50 mg) slowly IV (over 5 minutes) or IM; may repeat every 8 hours at doses of 5–100 mg. For Wernicke encephalopathy, follow with daily parenteral doses of 50–100 mg until the patient is taking a regular diet. Doses as high as 1 g over the first 12 hours have been given to patients with acute Wernicke-Korsakoff syndrome.
Parenteral. Thiamine hydrochloride (various), 100 mg/mL, in 1- and 2-mL Tubex and multiple-dose vials (vials may contain benzyl alcohol).
Suggested minimum stocking levels to treat a 100-kg adult for the first 8 hours and 24 hours: thiamine hydrochloride, first 8 hours: 600 mg or three multiple-dose vials (100 mg/mL, 2 mL each); first 24 hours: 1000 mg or five multiple-dose vials (100 mg/mL, 2 mL each).