ABSORPTION, UTILIZATION AND CLINICAL EFFECTIVENESS OF ALLITHIAMINES COMPARED TO

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1 J. Nutr. Sci. Vitaminol., 22 (Suppl.), 63-68, 1976 ABSORPTION, UTILIZATION AND CLINICAL EFFECTIVENESS OF ALLITHIAMINES COMPARED TO WATER-SOLUBLE THIAMINES Herman Baker and Oscar Frank Departments of Medicine and Preventive Medicine, New Jersey Medical School, East Orange, New Jersey 07018, U.S.A. Summary Oral administration of lipid soluble allithiamines [thiamine propyl disulfide (TPD) and thiamine tetrahydrofurfuryl disul fide (TTHF)] rapidly increased thiamine ac tivity in whole blood, red blood cells, cere brospinal fluid, and urine in normal and thia mine-deficient subjects. These thiamine con geners also restored red blood cell transketolase to normal in alcoholics with thiamine de ficiency. Such repletion equaled that produced by parenteral, water-soluble thiamine hydro chloride (THCI) or thiamine pyrophosphate (TPP). Oral administration of water-soluble thiamines (THCI, TPP) neither elevated thia mine activity in biological fluids nor restored transketolase activity to normal in alcoholics with thiamine deficiency presumably due to their rate-limited intestinal transport. Oral administration of TPD eliminated lateral rectos palsy in patients with Wernicke's encephalo - pathy. Orally administered allithiamine vita - mers are therefore recommended for pro phylaxis and treatment of thiamine deficits because while having essentially the same bio logical properties as parenterally administered water-soluble thiamines they have not produced any untoward effects after long-term adminis tration and are far more efficiently utilized. In man, thiamine hydrochloride (THCl) is absorbed in limited quantities by a saturable, specialized entry mechanism (1-3); absorption is thus rate-limited and consistent with the Michaelis-Menton relationship describing simple enzyme-substrate reactions (3). The kinetics of 35S-THCl entry indicates that ethanol or dietary deficiency markedly reduces intestinal absorption of THCI (4, 5). In con trast, the sparingly water-soluble, more lipid soluble allithiamines (Fig. 1), e.g., thiamine propyl disulfide (TPD) and thiamine tetra hydrofurfuryl disulfide (TTHF) are largely absorbed without severe limits (6, 7). We show here that the allithiamines given orally efficient ly correct thiamine depletion and produce circulatory levels of metabolizable thiamine comparably high to those seen with parenterally administered THCI and thiamine pyrophos phate (TPP). We also compared: a) absorp tion of THCI, TPP, TPD, and TTHF in man as Fig. 1. Structure of allithiamines and water-soluble thiamines.

2 64 H. BAKER and O. FRANK determined by the increase in circulating thia mine activity and increase in portal venous blood, b) penetration of the various thiamine congeners into red blood cells (RBC) and passage into the cerebrospinal fluid (CSF), and c) their ability to correct biochemical evidence, e.g., transketolase, of thiamine deple tion. EXPERIMENTAL Twenty-four subjects without any evidence of nutritional deficiency, 20 alcoholics without signs of liver, neurological disease, or nutri tional deficiency and 48 alcoholics with clinical evidence of hypovitaminosis with or without liver disease and neurological abnormalities were studied. All these subjects were men 30 to 45 years old. The studies included com prehensive blood and urine analyses, and red blood cell (RBC) transketolase (8). Circu latory vitamins were also measured; vitamins A, carotene, E and C chemically (9); biotin, B12, pantothenate, B6, nicotinate, riboflavin by protozoologic assay. Circulating folates were measured with Lactobacillus casei (9). Assay for the metabolic forms of thiamine in biologic fluids and growth activity of THCI, TPP, TPD, and TTHF were performed with the protozoan Ochromonas danica (9). Ten ml of blood was drawn from an anti cubital vein (after the subject had fasted over night) into tubes containing 0.2ml 25% sodium citrate before, and 1/2, 1, 2, 3, 4, 6, and 24hr after administration of 50mg of THCI, TPD, TPP, or TTHF. One ml of whole blood was saved for thiamine assay; RBC were obtained from the remainder of the sample. RBC were prepared for thiamine assay by centrifuging off the plasma from the whole blood and then washing the RBC with 0.9% NaCI (saline) 3 times. Urine was collected for 24hr before and after the test dose. The same subjects were given a different form of thiamine at weekly intervals, and the same procedure as listed above was followed each time. TTHF and TPD were obtained from Takeda Chemicals Industries, Ltd., Doshomachi 2-Chome, Higashi-ku, Osaka, Japan; TPP was obtained from Barrows Biochemical Products Corp., Inwood, New York; THCI was obtained from Abbott Laboratories, North Chicago, Illinois; we thank these firms. Blood for assay of transketolase was obtained before and 24hr after oral administration of 50mg of one or the other forms of thiamine. Combined hepatic and umbilical vein catheteri zation (10) in 4 patients with cirrhosis was used to compare the route of absorption of TPD and THCI. Clinical effectiveness of TPD and THCI were compared in 6 patients with Wernicke's encephalopathy. Two or more observers independently assessed the degree of ocular palsy and its response to the various thiamine treatments. Fig. 2. Growth of Ochromonas danica with various thiamines. RESULTS Equimolar TPP, TPD and TTHF support growth of O. danica as well as THCI dose (Fig. 2). Oral administration of 50mg of TTHF or TPD to healthy volunteers increased thiamine activity in whole blood, RBC, and CSF (Tables 1-3). Fifty mg of orally ad ministered TPP or THCI did not increase thiamine activity to the same extent; only intravenous thiamine administration of THCI and TPP increased thiamine activity to the same level as produced by the oral admin istration of TPD or TTHF (Tables 1-3). Healthy volunteers ingesting 50mg THCI

3 THIAMINE SYMPOSIUM 65 Table 1. Thiamine activity (ng/ml) in whole blood after 50mg p.o. and i. v, of various vitamers.a a Means of 6-22 determinations. Table 2. Thiamine activity (ng/ml) in red blood cells after 50mg p.o. and i. v. of various vitamers.a a Means of 6-31 determinations. Table 3. Thiamine activity (ng/ml) in CSF after p. o. and i. v. administration.a Fig. 3. Thiamine activity in blood and urine after oral administration and absorption of 50mg thiamine hydrochloride or thiamine propyl disul fide in normal and thiamine-deficient subjects. œ- œ, thiamine propyl disulfide (TPD); hydrochloride (THCl). 50mg TPD in normal subjects. Urinary thiamine increased to 1.42 }0.25mg after a 50mg dose; means of 6-16 determinations. had a slight increase in circulating thiamine. Thiamine-deficient alcoholics who were ingest ing alcoholic beverages, showed little or no increase in circulating thiamine. Both normal and thiamine-deficient subjects showed sig nificant increases in circulating thiamine ac tivity after ingestion of TPD (Fig. 3); circulat ing thiamine was increased after oral TPD in the deficient alcoholics even while they were ingesting alcoholic beverages (Fig. 3). Urinary excretion of thiamine during a 24-hr period increased linearly from 1.86 }0.05mg to 7.8 }1.3mg with administration of 10 to 10 to 50mg of THCI in normal subjects. Except for diminished excretion of thiamine after THCI, in malnourished thiamine-deficient alcoholics as would be expected from the decreased absorption noted above, the same pattern as for normal subjects in thiamine excretion was seen after TPD ingestion (Fig. 3). Oral administration of 50 mg of TPD to healthy subjects produced a rise in portal venous thiamine of 4,000ng/ml within 5 min, whereas 50mg of THCI increased portal venous thiamine to only 90ng/ml within 1 hr (Fig. 4). The increase in thiamine first ap peared in portal venous blood, then in hepatic vonous blood, finally in femoral arterial blood after TPD or THCI.

4 66 H. BAKER and O. FRANK Fig. 4. Thiamine activity in hepatic and portal venous blood and femoral artery blood after 50mg of orally administered thiamine propyl disulfide (TPD) or thiamine hydrochloride (THCl). Fig. 6. Comparison of the response of clinical labo ratory abnormalities in thiamine-deficient alcoholics with Wernicke's encephalopathy after oral ad - ministration of 50mg thiamine hydrochloride (THCI) or thiamine propyl disulfide (TPD). Fig. 5. Transketolase activity in patients with thiamine depletion before and after receipt of 50mg of thiamine propyl disulfide (TPD) or thiamine hydrochloride (THCI). œ, after treatment;, before treatment. Oral administration of 50mg THCI did not restore RBC transketolase activity to normal whereas enzyme activity rose to normal within 24hr in 5 of 7 subjects with clinical evidence of thiamine depletion who received 50mg TPD (Fig. 5). CSF thiamine was 23.6 }6.4ng/ml in healthy subjects and 3.2 }1.2ng/ml in subjects with Wernicke's encephalopathy. Lateral rectos palsy disappeared within 6-8hr in each of 6 patients with Wernicke's encephalopathy after oral administration of 50mg TPD but not after oral THCI treatment (Fig. 6). Improve ment was associated with increase of CSF and whole blood thiamine to supranormal levels within 1-4hr after treatment with oral TPD. Confabulation, ataxia, and peripheral neuropa thy also disappeared in 4 patients who received only 20mg of TPD daily for 6 weeks. DISCUSSION O. danica has a sensitive and specific thia mine requirement. It was developed as a microbial reagent for thiamine in blood, serum, CSF, urine, nerve tissue, muscle, and liver tissue (9). O. danica's requirement for intact thiamine parallels that of man and vertebrates, moreover, its phagotrophy may also serve to make available bound thiamine, as presumably man's digestive system does. Because the thiamine requirement of O. danica is of the

5 THIAMINE SYMPOSIUM 67 mammalian type it provides information on the availability of metabolically active thiamine. Our results (Fig. 2) show that THCI, TPP, TPD and TTHF all had full thiamine activity for O. danica-a sign that they should satisfy the thiamine requirement of man. As with all metabolically active compounds, activity de pends on delivery to the target systems. TTHF and TPD would appear to be excellent thiamines for oral use on the principle that absorption of a drug after oral administration is inferable from plasma concentration (11); both compounds sharply elevate circulating thiamine. Peak thiamine activity is reached in 1 to 3 hr; the circulating concentration is almost identical after oral administration as after parenteral administration of THCI or TPP (Tables 1-3). In contrast to TPP and THCI, our observations indicate that oral absorption of TPD and TTHF is rapid. The allithiamines are absorbed without limit (12), whereas THCI is absorbed by a quickly evident rate-limited process (1, 13). This may explain the heightened circulating levels permitted by TTHF and TPD. The allithiamines presuma bly owe their good absorption and rapid trans ference to the tissue to their fat-solubility and ease of transport across the intestinal wall (12). They are absorbed well through the portal system (Fig. 4) as are water-soluble vitamins. TPP, like THCI, is not absorbed through the gut as well as TPD or TTHF (Tables 1-3) indicating that the intestinal cell is not highly permeable to this phosphorylated thiamine. Only a limited amount of THCI or TPP can therefore be absorbed from a single oral dose and limits the therapeutic usefullness of orally administered THCI and TPP; this is not so with the fat-soluble allithiamines (Tables 1-3). Clinical and laboratory signs of thiamine deficiency often appear in alcoholics despite intake of the established daily minimal re quirement for thiamine (14). This could result from poor absorption of the THCI usually employed in food and multivitamin supple ments. Ethanol (EtOH) or malnutrition may markedly reduce intestinal absorption of THCI. Our studies here indicate that TPD absorption is not impaired in alcoholics nor its absorption inhibited as with THCI (Fig. 3). Although repeated oral doses of THCI may eventually correct thiamine depletion, it should not be relied upon for severely deficient patients. This was demonstrated in patients with Wernicke's encephalopathy (10): oral THCI did not signifi cantly increase whole blood, RBC, CSF thia mine, and red cell transketolase during a 48-hr period but equimolar quantities of oral TPD rapidly corrected the clinical and laboratory signs of thiamine deficiency (Figs. 5 and 6). No toxic effects accompanied 3 to 6 months of continually large oral TPD doses. As shown here, both TPD and TTHF given orally increase whole blood, RBC, and CSF thiamine activity in the same manner as parenteral THCI and TPP (Tables 1-3), and should therefore have the same pharmacological and therapeutic properties as parenteral THCI. The safety and high oral effectiveness of the fat-soluble thia mines (12) (Tables 1-3) should make them preferable to the water-soluble forms for treating thiamine deficits associated with malnutrition, liver disease, and beriberi as well as for use in fortification of flour and in multivitamin preparations. REFERENCES 1) Morrison, A. B, and Campbell, J. A., J. Nutr., 72, 435 (1960). 2) Levy, G. and Hewitt, R. R., Am. J. Clin. Nutr., 24, 401 (1971). 3) Thomson, A. D. and Leevy, C. M., Clin. Sci., 43, 153 (1972). 4) Thomson, A. D., Baker, H., and Leevy, C. M., J. Lab. Clin.Med., 76, 34 (1970). 5) Tomasulo, P. A., Kater, R. M. H., and Iber, F. L., Am. J. Clin. Nutr., 21, 1341 (1968). 6) Fujiwara, M., in N. Shimazono and E. Katsura (Editors), Review of Japanese Literature on Beriberi and Thiamine, Igaku Shoin, Ltd., Tokyo, p. 179 (1965). 7) Baker, H., Thomson, A. D., Frank, O., and Leevy, C. M., Am. J. Clin. Nutr., 27, 676 (1974). 8) Schouten, H., van Eps Statius, L. W., and Boudier Struyker, A. M., Clin. Chim. Acta, 10, 474 (1964). 9) Baker, H. and Frank, O., in Clinical Vitaminology

6 68 H. BAKER and O. FRANK Methods and Interpretation, Wiley Interscience, New York (1968). 10) Thomson, A. D., Baker, H., and Leevy, C. M., J. Lab. Clin. Med., 76, 537 (1968). 11) Brodie, B. B., in Ciba Foundation Symposium, Little, Brown and Co., Boston, Mass., p. 188 (1967). 12) Fujiwara, M., in N. Shimazono and E. Katsura (Editors), Review of Japanese Literature on Beriberi and Thiamine, Igaku Shoin, Ltd., Tokyo, p. 187 (1965). 13) Rindi, G. and Ventura, U., Physiol. Rev., 52, 821 (1972). 14) Leevy, C. M., Thomson, A. D., and Baker, H., Am. J. Clin. Nutr., 23, 493 (1970).