DE4110562C2 - Means to study bile acid metabolism - Google Patents

Description

The invention relates to an agent for examining the bile acid metabolism, d. H. of enterohepatic bile acid circulatory.

Certain disorders of the bile acid metabolism can be after applying duodenal probes and after taking blood Characterize determination of bile acids. An essential one The disadvantage of these methods is their invasive nature (e.g. H. Senger, R. Pludra, W. Braun: A fast thin-layer chroma topographic, quantitative determination of conjugated galls acids in duodenal juice without prior extraction, Z. med. Lab-Diagn. 25: 52-55 (1984); U. Foberg u. a .: Evaluation of an oral bile acid loading test for assessment of liver func tion in chronic hepatitis, Liver 7 (1987) 116-122). At some of these methods are also radioactive oil load (E. Stahl, B. Arnesjö: Taurocholate meta bolism in man, Scand. J. Gastroent. 7 (1972) 559-566; H. Nyhlin et al. a .: Clinical application of a selenium (⁷⁵Se) label led bile acid for the investigation of terminal ileal func tion, hepato-gastroenterol. 31 (1984) 187-191).

Various isotopically labeled agents were therefore pre-selected suggest that after oral or intravenous administration a bloodless, non-invasive examination of the bile acid should enable change. However, none of these means is suitable, quantitatively the actual proportion of the bacteria len deconjugation in the intestine or the real temporal conc course of the cycle (cycle frequency, pool size) of cholic acid conjugates non-invasively, bloodless and radioactivity-free measure up. So z. B. the proposed funds for ¹⁴C- or 13 C-glycocholate-CO₂ breath tests (E. Hess Thaysen: Diagnostic value of the ¹⁴C-cholylglycine breath test. Clin. Gastro enterol. 6 (1977) 227; N. W. Solomons et al. a .: Application of a stable isotope (13 C) -labeled glycocholate breath test to diagnosis of bacterial overgrowth and ileal dysfunction. J. Lab. Clin. Med. 90 (1977) 431-439) is unsuitable because  the isotope content measured in the breathing air by various whose further upstream endogenous processes are falsified (e.g. decreased by reutilization of the split off ¹³C / ¹⁴C-Glycins for protein synthesis and by isotope ver thinning due to CO₂ production due to other endogenous Operations as the 13 C / 11 C glycine oxidation).

The invention is intended to provide a means which the nonin vasive, bloodless and radioactivity-free examination of the Bile acid metabolism allowed without the measurement results by other endogenous ones not belonging to the object of investigation Operations are falsified.

The agent according to the invention is Na- [¹⁵N] taurocholate, i. H. which constitutes a substantial proportion of the bile acid conjugates natural taurocholate, but in which the ratio of Nitrogen isotopes in the nitrogen atom of the taurine part of the sub strong from 0.365 atomic% ¹⁵N to 99.635 atomic% ¹unN most of the ¹⁵N is changed (e.g. to 95 atomic 0% ¹⁵N to 5 atomic% ¹⁴N).

The biochemical behavior of these compounds is determined by the changed isotope ratio not affected. Medium high sensitive isotope meters, e.g. B. mass spectrometer but the orally administered [¹⁵N] taurocholate from the endogenous Distinguish taurocholate. Evidence of ¹⁵N as a measure of Bile acid transport disorders, bacterial overgrowth or other illnesses are done in a simple way Taurine [¹in-N] tau excreted naturally in the urine rin mixture.

The use of [¹⁵N] taurocholate for diagnostic purposes is carried out by oral administration from 3 to 10 Milligrams per kg body mass as an aqueous solution. Subsequently is total of 12 hours of spontaneous urine in single portions melts and both the total nitrogen and the total ¹⁵N- Enrichment of each sample (using known methods) determined. Using the well-known formulas of isotope dilution analysis and (modified) formulas of pharmacokinetics is then the  Kinetics of taurine / [¹⁵N] taurine release in the course of enterohepatic circulation calculated.

People with undisturbed enterohepatic bile acid circuit Runs pass through the urine almost within 5 hours no ¹⁵N above the natural frequency. In the event of pathological growth of bacteria in the small intestine is the result increased enzymatic cleavage of the [¹⁵N] taurocholate be Already after 3 hours there is an increase in ¹⁵N accumulation in the urine measured. A corresponding differentiation is also in the Case of bowel disease with a decreased resorp tion of the bile acids. Diminished tauro cholate absorption means increased enzymatic cleavage and thus increased [¹⁵N] urine taurine excretion.

The Na- [¹⁵N] taurocholate is prepared by Um Sodium bromethanesulfonate with [¹⁵N] ammonia (the can be obtained from commercially available [¹⁵N] ammonium sulfate can):

[Br-CH₂-CH₂-SO₃ ^- ] Na⁺ + ¹⁵NH₄OH → ¹⁵NH₂-CH₂-CH₂-SO₃H.

The resulting [¹⁵N] taurine is present with cholic acid a specific catalyst (EEDQ: ethyl-2-ethoxy-1,2- dihydroquinoline carboxylate) brought to reaction. With more repeated recrystallization from a mixture of 1 part water and 5 parts of alcohol form Na [¹⁵N] taurocholate (MW 538.6) in the purity necessary for pharmaceutical purposes. The ¹⁵N enrichment is at least 90 atomic% ¹⁵N.

The advantage of the invention is that it is well tolerated Indicated, non-toxic, radioactivity-free agent after oral application, the bile acid cycle as an endogenous natural substance, others on the other hand in the excretion products (urine, faeces) clear, simple and fast as a highly specific brand cation substance can be recognized. So this is it Particularly good for the special diagnosis of disorders of the Suitable for bile acid metabolism in early childhood  net, d. i.e. in toddlers, newborns and premature babies.

In immature premature babies, the exact characterization is a disturbed enterohepatic circulation of the bile acids especially important because this dietary disorder provo can be decorated ("protein-induced cholestasis"). As soon as the Deficiency is defined, the diet can be adjusted accordingly be fit.

In addition, further information on the biliary secretion performance or the cycle frequency of the taurocholate ge be obtained if, in addition to the urine samples, duode Nalsaft and venous blood taken at certain intervals and is analyzed (e.g. by chromatographic separation the ¹⁵N-bile acid conjugate and the ¹⁵N-conjugation partner).

The invention is intended to be explained in more detail on the basis of exemplary embodiments are explained.

• 1. An aqueous solution of sodium [¹⁵N] taurocholate is an adult patient suspected of having disorders of the Bile acid metabolism as a test drink (5 mg / kg body mass) administered. After a 12-hour fasting peel period (overnight) the patient receives a so-called Lundh meal (milk, raw egg and sunflower oil) for Stimulation of the gallbladder contraction. The spontaneous urine the patient becomes complete and over a further 12 hours collected in portions and on the respective nitrogen and ¹⁵N content examined. The kinetics of the ¹⁵N excretion The calculation that is calculated from this is a measure of one normal or increased bacterial cleavage of the bile acid conjugates in the intestine or for the absorption of the conjugates.
• 2. An aqueous solution of 8 mg sodium [¹⁵N] taurocholate is given orally to a 2 kg newborn. Of the Spontaneous urine is collected in portions over 12 hours and on its respective nitrogen and ¹⁵N content below is looking for. The kinetics of the ¹⁵N- calculated from the individual data Elimination is a measure of prenatal (at Un  examination on the 1st or 2nd day of life) or postnatal (in the case of repeat examinations on the 10th day of life) Develop dysfunction of the bile acid metabolism. That means is also good for repeat and follow-up exams suitable.

Claims (2)

1. Means for studying the bile acid metabolism, characterized in that it consists of sodium taurocholate, in which the ratio of the nitrogen isotopes in the nitrogen atom of taurine in part of the substance is changed from 0.365 atomic% ¹⁵N to 99.635 atomic% ¹ verändertN in favor of ¹⁵N. 2. Composition according to claim 1, characterized in that it is a ratio nis ¹⁵N to ¹⁴N of at least 90 atomic% ¹⁵N to 10 atomic% Has ¹⁴N.