Thiamine

# Thiamine ## Overview - **Classification**: Water-soluble vitamin (Vitamin B1) - **Mechanism**: Essential coenzyme for carbohydrate metabolism, vital for neural function and energy production. ## Primary Indications 1. **Thiamine Deficiency (Beriberi)**: Treatment and prevention of thiamine deficiency states. 2. **Wernicke-Korsakoff Syndrome**: Treatment of acute Wernicke's encephalopathy and prevention of Korsakoff psychosis, especially in chronic alcoholics. 3. **Metabolic Disorders**: Management of certain inherited metabolic disorders that are thiamine-responsive. ## Adult Dosing ### Standard Dosing **Acute Wernicke's Encephalopathy / Severe Deficiency** - **Dose**: **100-500 mg** - **Frequency**: **TID-QID** (3-4 times daily) - **Route**: **IV** (preferred) or IM - **Duration**: Until clinical improvement, then switch to oral. - **Special Consideration**: Administer **before** glucose infusion. **Mild/Moderate Thiamine Deficiency / Prophylaxis** - **Dose**: **5-30 mg** - **Frequency**: **Daily** - **Route**: **PO** **Alcohol Withdrawal (Prophylaxis)** - **Dose**: **100 mg** - **Frequency**: **Daily** - **Route**: **PO**, **IM**, or **IV** ### Dose Adjustments - **Renal Impairment**: No specific dose adjustments required. Thiamine is water-soluble. - **Hepatic Impairment**: No specific dose adjustments required. - **Elderly Patients**: No specific dose adjustments, but monitor for increased risk of deficiency. ## Pediatric Dosing ### Neonates (0-28 days) - **Indication**: Severe thiamine deficiency, suspected metabolic disorders. - **Dose**: **10-25 mg** - **Frequency**: **IV/IM once daily** - **Maximum**: **25 mg/day** (for deficiency, higher for metabolic conditions) - **Special Notes**: Consider specific metabolic specialist guidance for higher doses. ### Infants (1-12 months) - **Indication**: Severe thiamine deficiency (e.g., infantile beriberi). - **Dose**: **10-25 mg** - **Frequency**: **IV/IM once daily** - **Maximum**: **50 mg/day** ### Children (1-12 years) - **Indication**: Acute Wernicke-like encephalopathy, severe deficiency. - **Dose**: **100 mg** - **Frequency**: **IV/IM once daily** - **Maximum**: **100 mg/day** (acute settings, for several days) ### Adolescents (13-18 years) - **Indication**: Acute Wernicke's, severe deficiency. - **Dose**: **100-500 mg** - **Frequency**: **IV/IM once daily** or **TID** for acute states. - **Maximum**: **500 mg/day** (acute settings, approach adult dosing). - **Special Notes**: Transition to oral therapy once clinically stable. ## Safety Information ### Contraindications - **Absolute**: Known hypersensitivity to thiamine or any components. ### Common Adverse Effects - **Common (1-10%)**: Injection site pain (IM), mild gastrointestinal upset (oral). - **Serious but Rare**: Anaphylaxis, angioedema, pruritus, sweating, nausea. (Mostly associated with IV, especially rapid administration). ### Key Drug Interactions - **Loop Diuretics (e.g., Furosemide)**: May increase urinary thiamine excretion, potentially exacerbating deficiency. Monitor patients on long-term diuretics. - **IV Glucose Infusion**: Administer thiamine **before** glucose in deficient patients. Glucose metabolism consumes thiamine, potentially worsening neurological symptoms. ## Monitoring & Follow-up - **Before Treatment**: Assess for clinical signs of deficiency (e.g., ataxia, nystagmus, confusion). - **During Treatment**: Monitor for resolution of neurological symptoms and improved mental status. - **Clinical Signs**: Improvement in gait, eye movements, cognitive function, and reduced nausea/vomiting. ## Clinical Pearls - 💡 **Always administer Thiamine BEFORE glucose** in patients with suspected deficiency (e.g., alcoholics) to prevent precipitating or worsening Wernicke's encephalopathy. - 💡 IV administration is preferred for acute severe deficiency due to potentially impaired oral absorption in these patients. - 💡 Oral thiamine is typically sufficient for maintenance or mild deficiency once acute symptoms resolve. - 💡 Large oral doses of thiamine may cause the urine to appear yellow, which is a harmless effect. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.