Kinetics of thiamin and thiamin phosphate esters in human blood, plasma and urine after 50 mg intravenously or orally

Abstract

The concentrations of thiamin and thiamin monophosphate and diphosphate in plasma and whole blood samples were assessed in six healthy subjects for 12 h and in urine for 24 h following an IV and PO bolus dose of 50 mg thiamin HCl. Unphosphorylated thiamin increased rapidly in plasma after IV administration and then decreased to its initial value within 12 h in all but one subject; the half-life was 96 min. Thiamin mono and -diphosphate increased moderately (56%), and decreased slowly; the half-life of diphosphate was 664 min. Within 24 h, 53% of the administered dose was recovered in the urine, indicating a restricted distribution. After oral administration, the peak thiamin concentration in plasma was reached after 53 min and the concentration then had increased to 179% of its initial value. The elimination half-life was 154 min, and only 2.5% of the given dose was recovered in the urine. The relative bioavailability of thiamin was 5.3%. A moderate amount of the administered thiamin was stored in blood. Other body tissues must play an important part, therefore, in the distribution of thiamin.

Benfotiamine, thiamine monophosphate chloride and thiamine pyrophosphate chloride, as sources of vitamin B1 added for nutritional purposes to food supplements - Scientific Opinion of the Panel on Food Additives and Nutrient Sources added to Food (ANS)

“…Data on the urinary excretion of thiamine after oral administration of a 50 mg bolus dose of thiamine hydrochloride indicate that the relative bioavailability is 5.3% (Tallaksen et al, 1993;Friedemann et al, 1948). A similarly low bioavailability is indicated by a comparison of the plasma thiamine concentration-time curves after oral and intravenous administration of doses of 50 -200 mg thiamine (Weber and Kewitz, 1985).…”

Re: Wernicke’s Encephalopathy After Laparoscopic Roux-en-Y Gastric Bypass: A Misdiagnosed Complication

“…In fact, biologic half-life time of oral administered thiamine is 154 min, whereas after i.v. administration, this is 96 min [5]. The time required to exhaust the total thiamine metabolic pool is approximately 20 days.…”

Thyrotoxicosis-associated Wernicke’s Encephalopathy

“…2 The half-life of thiamine after intravenous administration is 96 minutes, whereas the elimination halflife after oral administration is 154 minutes. 3 This short halflife explains the need of administering thiamine 3-4 times per day for patients with WE and those at risk of developing it.…”