COMPARATIVE AUTORADIOGRAPHIC INVESTIGATIONS ON THE TISSUE DISTRIBUTION OF BENFOTIAMINE VERSUS THIAMINE IN MICE

The tissue distribution of two therapeutically applied preparations of B-vitamins were investigated in blood and selected organs (liver, bra in, muscle, kidney) of laboratory mice using autoradiographic techniqu es. Incorporation of lipid-soluble H-3-benfotiamine (CAS 22457-89-2) a nd water-soluble H-3-thiaminehydrochloride (CAS 67-03-8) (200 mu Ci, e quivalent to 105 mg vitamin/kg body weight) was monitored between 0.75 and 168 h after an oral or subcutaneous administration. The labelled tissue slices were autoradiographically analysed after a differential histochemical extraction procedure to evaluate the respective total ra dioactivity, the uptake into lipid-soluble, water-soluble and residual macromolecular compounds. Evaluation of these autoradiographic data ( given as mu mol vitamin preparation/mg tissue equivalent) proved that benfotiamine is incorporated much better than thiaminehydrochloride in dependent of the administration mode. In muscle and brain tissue a 5 t o 25 fold higher amount of tracer incorporation was registered followi ng benfotiamine as compared with the thiamine application, whereas in all other organs the difference in the label was mostly between 10 and 40%. Concerning the organ specific distribution, liver and kidney wer e the structures labelled highest by both substances and administratio n procedures. In the liver, concerning all incorporation times, a high er proportion of residual macromolecular compounds was found, whereas in the kidney the proportions of lipid-as well as of water-soluble mat erials prevailed. These data should be clinically relevant.