Thiamine (IV/IM — Pabrinex)

VERBATIM §4.2, Adults, Wernicke-Korsakoff syndrome associated with alcohol use disorder: 'Prophylaxis in patients with high risk (e.g. hospitalised patients managed for alcohol withdrawal in presence of malnutrition): 250 mg by intramuscular or intravenous route once daily for 3 to 5 days. Treatment: 500 mg to 750 mg by intravenous route 3 times/day for at least 2 days (up to 1000 mg/dose during the first 12 hours may be used). In case of favourable response the treatment can be continued with 250 mg by intramuscular or intravenous route once daily for 5 days or until there is no further improvement. Maintenance treatment: the treatment should be continued with a suitable oral form of vitamin B1.' OTHER ADULT INDICATION IN THE SAME SECTION — BERIBERI, verbatim: 'Treatment: 10 mg – 20 mg by intramuscular injection or slow intravenous infusion (over 30 minutes) 3 times/day for up to 2 weeks. If severe life threatening form of beriberi (e.g. Shoshin beriberi): 100 mg to 300 mg/day by slow intravenous infusion. Maintenance treatment: the treatment should be continued with a suitable oral form of vitamin B1.' Note how far the beriberi figures sit below the Wernicke-Korsakoff ones — do not interchange them. GLUCOSE ORDER, §4.2 verbatim: 'Patients with marginal thiamine status to whom glucose is being administered should receive parenteral thiamine in each of the first few litres of IV fluid to avoid precipitating heart failure (see section 4.4).' §4.4 states the mechanism, verbatim: 'As thiamine plays the role of enzymatic cofactor in the normal metabolism of carbohydrates, a large intake of glucose quickly provokes a depletion of the reserves, and precipitates or aggravates Wernicke encephalopathy in patients suffering from underlying thiamine deficiency. It is consequently recommended to administer thiamine intravenously before or simultaneously with administration of glucose by bolus or by infusion.' ANAPHYLAXIS PRECAUTIONS, §4.4 verbatim: 'Anaphylactic reactions leading to shock have been reported after thiamine hydrochloride parenteral administration. This risk increases in case of repeated doses. An intradermal test dose is recommended prior to parenteral administration in patients suspected to be drug sensitive. Emergency medical equipment for treating anaphylactic shocks must be easily available.' and 'To reduce the risk of anaphylactic shock and reactions at the injection site, the intravenous injection must be administered slowly (over 30 minutes). Fast IV administration of thiamine has been associated with an immediate burning sensation in the arm after injection in the IV line, lasting seconds to minutes. This reaction can be avoided by slow administration into larger veins with higher IV fluid flow rates.' ELDERLY, §4.2 verbatim: 'There are no data available in the elderly. No dose adjustment is recommended for this population.' EXCIPIENT: 'This medicine contains less than 1 mmol sodium (23 mg) per 2 ml ampoule, that is to say essentially "sodium-free".' PRODUCT CHECK: 'Do not use this medicine if you notice visible particles in the solution, if the solution is not clear or if it contains a precipitate.' Each syringe/solution is for single individual use. US CROSS-CHECK, NOT ADOPTED: the US injection label in this bundle states 'In the treatment of Wernicke-Korsakoff syndrome, thiamine hydrochloride has been administered IV in an initial dose of 100 mg, followed by IM doses of 50 to 100 mg daily until the patient is consuming a regular, balanced diet' — an order of magnitude below the UK SPC, and not used here.

NOT WEIGHT-BASED — the SPC gives fixed milligram-per-day figures for children, not a per-kilogram dose, so dosePerKg is null and no volume calculation should be offered. The concentration recorded (125 mg/mL) is the strength named in the product title, 'Thiamine hydrochloride 125 mg/ml solution for injection'. INDICATION CAVEAT: the SPC's paediatric paragraph doses BERIBERI ONLY — it gives no paediatric regimen for Wernicke-Korsakoff syndrome, which is this page's primary use. §4.2 Paediatric population, verbatim in full: 'There is only limited experience with therapy in children and adolescents. Beriberi: Treatment: 10 mg to 25 mg/day by intramuscular injection or slow intravenous infusion for 2 weeks. IV doses of 100 mg/day or even higher may be needed in severe cases, for example 500 mg three times a day could be used (see section 5.1). Maintenance treatment: the treatment should be continued with a suitable oral form of vitamin B1.' Note that the '500 mg three times a day' phrase is offered as an example for severe cases, not as a ceiling and not as a general paediatric dose. Verify any paediatric dose against a children's formulary before use.