From the FDA Drug Label
DESCRIPTION Thiamine Hydrochloride Injection, USP is a sterile solution of thiamine hydrochloride in Water for Injection for intramuscular (IM) or slow intravenous (IV) administration. The FDA drug label does not answer the question.
From the Research
Thiamine should be administered intramuscularly at a dose of at least 100 mg daily for patients with suspected or confirmed thiamine deficiency, with higher doses of 500 mg three times daily for 2-3 days recommended for acute Wernicke's encephalopathy. The injection should be given deep into a large muscle, typically the gluteal muscle or vastus lateralis in the thigh, using a 21-23 gauge needle. Prior to administration, inspect the solution for particulate matter or discoloration.
Key Considerations
- For acute Wernicke's encephalopathy, higher doses are recommended, followed by 250 mg daily until symptoms improve 1.
- Common side effects include pain at the injection site, warmth, or mild burning sensations.
- Rare but serious allergic reactions can occur, so patients should be monitored for 30 minutes after the first dose 2.
- Thiamine administration is particularly important before giving glucose to malnourished patients or those with alcohol use disorder, as glucose can precipitate or worsen Wernicke's encephalopathy by depleting already low thiamine stores.
Administration Guidelines
- The intramuscular route is preferred in the outpatient setting, whereas the intravenous route is suggested for inpatients 3.
- Patients at high risk of Wernicke's encephalopathy should immediately receive an intravenous or intramuscular dose of thiamine; patients with suspected Wernicke's encephalopathy should preferably receive an intravenous dose 2.
- Reports of anaphylactic reaction to parenteral administration of thiamine are rare and are not a reason to refrain from parenteral treatment 2.
Special Considerations
- Some studies suggest that higher thiamine doses (over 500 mg/day) for a longer period (at least three months) than usually recommended should be tried in cases of undertreated Wernicke-Korsakoff syndrome 4.
- The vitamin is essential for carbohydrate metabolism and neurological function, with deficiency leading to conditions like beriberi and Wernicke-Korsakoff syndrome.