METHODS: After ingestion of a single dose of either 100 mg
thiamine nitrate (corresponding to 305 micromol
thiamine) or 100 mg
benfotiamine (corresponding to 214 micromol
thiamine), the blood levels of
thiamine phosphate esters were analysed by means of high-performance liquid chromatography for a 24-h period. The TDP concentration in erythrocytes was calculated using the haematocrit and TDP concentration in blood. Erythrocyte
transketolase activity and alpha-ETK were measured before and 10 h after administration. The pharmacokinetics of TDP in blood were compared with healthy subjects of other studies retrieved from database query.
RESULTS: Regarding the blood concentrations of TDP, the patients with
ESRD had a 4.3 times higher area under the concentration time curve after
benfotiamine administration than after
thiamine nitrate. After
benfotiamine administration, the peak plasma concentration of TDP exceeded that in healthy subjects by 51%. In the
ESRD patients, after 24 h, the mean TDP concentration in erythrocytes increased from 158.7+/-30.9 ng/ml initially to 325.8+/-50.9 ng/ml after administration of
benfotiamine and from 166.2+/-51.9 ng/ml to 200.5+/-50.0 ng/ml after
thiamine nitrate administration. The ratio between the maximum erythrocyte TDP concentration and basal concentration was 2.66+/-0.6 in the
benfotiamine group and 1.44+/-0.2 in the group receiving
thiamine nitrate (P < 0.001). After 24 h, it was 2.11+/-0.4 and 1.23+/-0.2, respectively. The
transketolase activity increased from 3.54+/-0.7 microkat/l initially to 3.84+/-0.6 microkat/l after
benfotiamine intake (P = 0.02) and from 3.71+/-0.8 microkat/l to 4.02+/-0.7 microkat/l after
thiamine nitrate intake (P = 0.08). Likewise, alpha-ETK decreased from initially 1.10+/-0.07 to 1.04+/-0.04 (P = 0.04) and from 1.12+/-0.05 to 1.08+/-0.06 (P = 0.09). After 24 h, the phosphorylation ratio in whole blood decreased from 12.9+/-6.9 initially to 5.6+/-3.2 after
benfotiamine administration (P = 0.02) and from 13.5+/-7.3 to 9.0+/-4.8 (P = 0.03) after administration of
thiamine nitrate. No correlation between erythrocyte TDP concentration and
transketolase activity and/or alpha-ETK was observed in
ESRD patients, either before or 10 h after administration.
CONCLUSION: