THIAMINE HCL

VITAMIN B 1 Chemistry - A water-soluble B-complex vitamin, thiamine HCl occurs as bitter-tasting, white, smallhygroscopic crystals, or crystalline powder that has a characteristic yeast-like odor. Thiamine HClis freely soluble in water and slightly soluble in alcohol and has pKas of 4.8 & 9.0. Thecommercially available injection has a pH of 2.5-4.5. Thiamine HCl may also be known as
Aneurine HCl, Thiamin HCl, Thiamine Chloride, Thiaminium Chloride Hydrochloride, or Vitamin
B1.

Storage, Stability, Compatibility

Thiamine HCl for injection should be protected from light andstored at temperatures less than 40°C and preferably between 15-30°C; avoid freezing.
Thiamine HCl is unstable in alkaline or neutral solutions or with oxidizing or reducing agents. It ismost stable at a pH of 2.
Thiamine HCl is reportedly compatible with all commonly used intravenous replacement fluids.
Compatibility is dependent upon factors such as pH, concentration, temperature and diluents used.
It is suggested to consult specialized references for more specific information (e.g., Handbook on
Injectable Drugs by Trissel; see bibliography).

Pharmacology - THIAMINE HCL

Thiamine combines with adenosine triphosphate (ATP) to form a compound(thiamine diphosphate/thiamine pyrophosphate) that is employed for carbohydrate metabolism, butdoes not effect blood glucose concentrations.
Absence of thiamine results in decreased transketolase activity in red blood cells and increasedpyruvic acid blood concentrations. Without thiamine triphosphate, pyruvic acid is not converted intoacetyl-CoA, diminished NADH results with anaerobic glycolysis producing lactic acid. Lactic acidproduction is further increased secondary to pyruvic acid conversion. Lactic acidosis may occur.

Uses, Indications

Thiamine is indicated in the treatment or prevention of thiamine deficiencystates. Symptoms of thiamine deficiency may be manifested as gastrointestinal (anorexia, salivation), neuromuscular/CNS signs (ataxia, seizures, loss of reflexes), or cardiac effects (brady- ortachyarrhythmias). Deficiency states may be secondary to either a lack of thiamine in the diet or thepresence of thiamine destroying compounds in the diet (e.g., bracken fern, raw fish, amprolium, thiaminase-producing bacteria in ruminants).
Thiamine has also been used in the adjunctive treatment of lead poisoning and ethylene glycoltoxicity (to facilitate the conversion of glyoxylate to nontoxic metabolites).

Pharmacokinetics - THIAMINE HCL

Thiamine is absorbed from the GI tract and is metabolized by the liver.
Elimination is renal, the majority being metabolites.

Contraindications, Precautions, Reproductive Safety

Thiamine injection is contraindicated inanimals hypersensitive to it or any component of it.

Adverse Effects, Warnings

Hypersensitivity reactions have occurred after injecting this agent.
Some tenderness or muscle soreness may result after IM injection.

Overdosage, Acute Toxicity

Very large doses of thiamine in laboratory animals have been associated with neuromuscular or ganglionic blockade, but the clinical significance is unknown.
Hypotension and respiratory depression may also occur with massive doses. A lethal dose of 350mg/kg has been reported. Generally, no treatment should be required with most overdoses.

Drug Interactions

Thiamine may enhance the activity of neuromuscular blocking agents;clinical significance is unknown.
Drug/Laboratory Interactions - Thiamine may cause false-positive serum uric acid results whenusing the phosphotungstate method of determination or urobilinogen urine spot tests using
Ehrlich's reagent. The Schack and Wexler method of determining theophylline concentrationsmay be interfered with by large doses of thiamine.