THIAMINE HYDROCHLORIDE (VITAMIN B1)

THIAMINE HYDROCHLORIDE (VITAMIN B1)
(thye'a-min)
Classifications: vitamin b1;
Therapeutic: vitamin b1 replacement therapy

Pregnancy Category: A, C if dose is above RDA

Availability

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

Action

Water-soluble B1 vitamin and member of B-complex group used for thiamine replacement therapy. Functions as an essential coenzyme in carbohydrate metabolism and has a role in conversion of tryptophan to nicotinamide.

Therapeutic Effect

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

Pregnancy (category C if dose is above RDA).

Cautious Use

Pregnancy (category A).

Route & Dosage

Thiamine Deficiency
Adult: IV/IM 50–100 mg t.i.d., then 5–10 mg PO for 1 mo
Child: IV/IM 10–25 mg t.i.d. then, 5–10 mg PO for 1 mo

Alcohol Withdrawal
Adult: IV/IM 100 mg/d until PO 50–100 mg/d as tolerated

Wernicke's Encephalopathy
Adult: IV/IM 100 mg/d then 50–100 mg/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, 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 from GI tract. Distribution: Widely distributed, including into breast milk. Elimination: 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

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