THIAMINE HYDROCHLORIDE (VITAMIN B₁)
(thye'a-min)
Betalins, Bewon, Biamine
Classifications: vitamin b
Pregnancy Category: A

Availability

50 mg, 100 mg, 250 mg tablets; 20 mg enteric-coated tablet; 100 mg/mL injection

Actions

Water-soluble B₁ vitamin and member of B-complex group used for thiamine replacement therapy.

Therapeutic Effects

Functions as an essential coenzyme in carbohydrate metabolism. Also has role in conversion of tryptophan to nicotinamide. Effectiveness is evidenced by improvement of clinical manifestations of thiamine deficiency: Anorexia, gastric distress, depression, irritability, insomnia, palpitations, tachycardia, loss of memory, paresthesias, muscle weakness and pain, elevated blood pyruvic acid level (diagnostic test for thiamine deficiency), and elevated lactic acid level.

Uses

Treatment and prophylaxis of beriberi, to correct anorexia due to thiamine deficiency states, and in treatment of neuritis associated with pregnancy, pellagra, and alcoholism, including Wernicke-Korsakoff syndrome. Therapy generally includes other members of vitamin B complex, since thiamine deficiency rarely occurs alone. Severe deficiency is characterized by ophthalmoplegia, polyneuropathy, muscle wasting ("dry" beriberi), edema, serous effusions, and CHF ("wet" beriberi).

Contraindications

None

Route & Dosage

Thiamine Deficiency
Adult: IV/IM 50–100 mg t.i.d.
Child: IV/IM 10–25 mg t.i.d.

Beriberi
Adult: IV/IM 10–500 mg t.i.d. for 2 wk or until on normal diet
Child: IV/IM 10–50 mg t.i.d. until on normal diet

Dietary Supplement
Adult: PO 15–30 mg/d
Child: PO 10–50 mg/d

Administration

Oral

Do not crush or chew enteric-coated tablets. These must be swallowed whole.

Intramuscular

Give deep IM into a large muscle; may be painful. Rotate sites and apply cold compresses to area if necessary for relief of discomfort.

Intravenous

Note: Intradermal test dose is recommended prior to administration in suspected thiamine sensitivity. Deaths have occurred following IV use.

PREPARE: Direct: Give undiluted. IV Infusion: Diluted in 1000 mL of most IV solutions.

ADMINISTER: Direct: Give at a rate of 100 mg over 5 min. IV Infusion: Give at the ordered rate.

INCOMPATIBILITIES Solution/additive: Amobarbital, diazepam, erythromycin, furosemide, phenobarbital.

Preserve in tight, light-resistant, nonmetallic containers. Thiamine is unstable in alkaline solutions (e.g., solutions of acetates, barbiturates, bicarbonates, carbonates, citrates) and neutral solutions.

Adverse Effects (1%)

Body as a Whole: Feeling of warmth, weakness, sweating, restlessness, tightness of throat, angioneurotic edema, anaphylaxis. Respiratory: Cyanosis, pulmonary edema. CV: Cardiovascular collapse, slight fall in BP following rapid IV administration. GI: GI hemorrhage, nausea. Skin: Urticaria, pruritus.

Interactions

Drug: No clinically significant interactions established.

Pharmacokinetics

Absorption: Limited absorption from GI tract. Distribution: Widely distributed, including into breast milk. Elimination: Excreted in urine.

Nursing Implications

Assessment & Drug Effects

Record patient's dietary history carefully as an essential part of vitamin replacement therapy. Collaborate with physician, dietitian, patient, and responsible family member in developing a diet teaching plan that can be sustained by patient.
Note: Body requirement of thiamine is directly proportional to carbohydrate intake and metabolic rate; requirement increases when diet consists predominantly of carbohydrates. Total absence of dietary thiamine produce deficiency state in about 3 wk.

Patient & Family Education

Food–drug relationships: Learn about rich dietary sources of thiamine (e.g., yeast, pork, beef, liver, wheat and other whole grains, nutrient-added breakfast cereals, fresh vegetables, especially peas and dried beans).

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug