THIAMINE HYDROCHLORIDE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for THIAMINE HYDROCHLORIDE (THIAMINE HYDROCHLORIDE).
Thiamine hydrochloride is a water-soluble vitamin that acts as a cofactor for several enzymes involved in carbohydrate metabolism, including transketolase, pyruvate dehydrogenase, and α-ketoglutarate dehydrogenase. It is essential for the decarboxylation of α-keto acids and pentose phosphate pathway activity.
| Metabolism | Thiamine is converted to its active form, thiamine pyrophosphate (TPP), via phosphorylation by thiamine pyrophosphokinase, primarily in the liver. It is not extensively metabolized by cytochrome P450 enzymes. Excretion is renal, with minor biliary elimination. |
| Excretion | Renal: 40-50% as unchanged drug; metabolites: thiamine pyrophosphate, thiamine monophosphate. Fecal: minimal (<5%). |
| Half-life | Terminal half-life: 9-18 days for whole body stores; plasma half-life: 1.5-2 hours for free thiamine. |
| Protein binding | ~10% bound to albumin and other plasma proteins. |
| Volume of Distribution | Vd: 0.2-0.4 L/kg (total body water); reflects distribution to all tissues, especially skeletal muscle and heart. |
| Bioavailability | Oral: 3.7-5.3% (saturable transport); IM: near 100%. |
| Onset of Action | IV: minutes; IM: 30-60 minutes; Oral: several hours to days for repletion. |
| Duration of Action | Duration depends on tissue stores; single dose effects last days to weeks for deficiency correction. |
50-100 mg intravenously or intramuscularly once daily for deficiency; 100 mg intravenously for Wernicke encephalopathy (with 50-100 mg maintenance).
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment; for severe impairment (GFR < 30 mL/min), use with caution and monitor for accumulation. |
| Liver impairment | No dose adjustment required for any Child-Pugh class; caution in severe hepatic impairment due to potential for lactic acidosis. |
| Pediatric use | Infants: 10-25 mg intramuscularly or intravenously once daily; Children 1-18 years: 10-50 mg intramuscularly or intravenously once daily. For Wernicke encephalopathy: 5 mg/kg intravenously over 30 minutes (max 100 mg) once daily. |
| Geriatric use | No specific dose adjustment required; use standard adult dosing, but monitor for renal function as elderly may have reduced clearance. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for THIAMINE HYDROCHLORIDE (THIAMINE HYDROCHLORIDE).
| Breastfeeding | Thiamine is excreted into breast milk. The milk-to-plasma ratio is approximately 0.6. Thiamine is a normal component of breast milk and is necessary for infant health. Supplementation of thiamine during lactation is safe and may be required if maternal intake is inadequate. The American Academy of Pediatrics considers thiamine compatible with breastfeeding. |
| Teratogenic Risk | Thiamine hydrochloride is considered safe during pregnancy. No teratogenic effects have been reported in human studies. Thiamine is essential for fetal development, particularly neural tube formation. There is no evidence of increased risk of congenital anomalies at recommended doses. |
■ FDA Black Box Warning
No FDA boxed warnings.
| Common Effects | Injection site reactions pain swelling redness Allergic reaction Skin irritation Cough Decreased blood pressure |
| Serious Effects |
["Hypersensitivity to thiamine or any component of the formulation"]
| Precautions | ["Rare hypersensitivity reactions (e.g., anaphylaxis, angioedema) with parenteral administration","May interfere with some laboratory tests (e.g., urine catecholamines, serum uric acid)","Use with caution in patients with low serum folate or vitamin B12 levels due to potential masking of megaloblastic anemia","Parenteral administration should be used only if oral therapy is not feasible; observe for injection site reactions"] |
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| Fetal Monitoring | No specific maternal-fetal monitoring is required for thiamine administration at recommended doses. In cases of high-dose therapy or parenteral administration, monitor for adverse effects such as allergic reactions or anaphylaxis. Assess maternal thiamine status in at-risk populations (e.g., hyperemesis gravidarum, malnutrition). |
| Fertility Effects | Thiamine is not known to adversely affect fertility. Adequate thiamine status is necessary for normal reproductive function and fetal development. Thiamine deficiency may impair fertility, but supplementation is not associated with negative reproductive outcomes. |