Adults

For severe deficiency, 100 mg IM daily for several days, then switch to oral supplementation. For Wernicke-Korsakoff syndrome, 100-200 mg IM/IV three times daily until symptoms improve.

Elderly

No specific dosage adjustment for elderly patients, but consider age-related physiological changes and potential renal impairment.

Renal_impairment

No specific dosage adjustment is generally required, but close monitoring is advised in severe renal impairment.

Onset

Within minutes to hours for symptomatic relief depending on the severity of deficiency and route of administration (faster with IV).

Excretion

Excreted primarily via the kidneys as metabolites or unchanged thiamine, especially after high doses.

Half life

Biphasic elimination with an initial half-life of 0.35 hours and a terminal half-life of 9-18 days.

Absorption

Rapidly absorbed after intramuscular (IM) injection. Plasma protein binding is minimal. Transport across the intestinal wall is dose-dependent.

Metabolism

Primarily metabolized in the liver to various inactive metabolites.

Fluorouracil

May inhibit the phosphorylation of thiamine to its active form, potentially exacerbating thiamine deficiency.

IV solutions containing sulfites

Sulfites can degrade thiamine, reducing its effectiveness. Avoid co-administration or monitor carefully.