Bile acids, solubility

Hofmann AF and Mysels 1. Bile-Acid Solubility and Precipitation In Vitro and In Vivo—the Role of Conjugation, Ph, and Ca2+ Ions. J Lipid Res 1992 33 617-626. 

Gallstones. Bile acids keep cholesterol soluble in gallbladder bile. Therefore, they are used for the dissolution of cholesterol gallstones. Initial treatment... 

Bile acid sequestrants may interfere with die digestion of fats and prevent die absorption of die fat-soluble vitamins (vitamins A, D, E, and K) and folic acid. When die bile acid sequestrants are used for long-term therapy, vitamins A and D may be given in a water-soluble form or administered parenterally. If bleedingtendencies occur as die result of vitamin K deficiency, parenteral vitamin K is administered for immediate treatment, and oral vitamin K is given for prevention of a deficiency in the futum... 

NORMAND F L, ORY R L, MOD R R (1987) Binding of bile acids and trace minerals by soluble hemicelluloses of rice The ability of rice fiber components to bind bile acids may play a role in lowering serum cholesterol. Food Technology, 41(2) 86-90. 

Lipids have been dehned on the basis of their stmctnre and solnbility. Lipids are natnrally occnrring componnds consisting of fatty acids and their derivatives, bile acids, pigments, vitamins, and steroids, as well as terpenoids, which are usually soluble in organic solvents such as benzene, chloroform, ether, and alcohol, etc., with variable solubility depending on the stmctnre of the lipid compound. 

Solubility and dissolution are processes that take place in the gastric and the luminal fluids, not on the surface of epithelial cells. Measurement of solubility ideally needs to take place at pH 1.7 (stomach) and pH 5-8 (small intestinal tract). Ideally, the screen media should resemble intestinal fluids and contain bile acid-lecithin mixed micelles. Fast and reliable techniques for assessing solubility in... 

Bile acids secreted into the small intestine facilitate absorption of fat-soluble vitamins and cholesterol. The majority of bile acids are reabsorbed from the intes-... 

Fig. 21.7. Solubility of a very poorly soluble drug, candersartan cilexitil, at different concentrations of bile acid/lecithin (2.5 1).

Reduced absorption due to complex formation or other interactions between drugs and intestinal components leading to poor absorption has been described in a few cases. One example is the precipitation of cationic drugs as very poorly-soluble salts with bile acids, which has been reported for several compounds [62], Another well-known example is the complex formation between tetracycline together with calcium due to chelation after administration of the drug together... 

Increased intake of soluble fiber in the form of oat bran, pectins, certain gums, and psyllium products can result in useful adjunctive reductions in total and LDL cholesterol (5% to 20%), but these dietary alterations or supplements should not be substituted for more active forms of treatment. They have little or no effect on HDL-C or triglyceride concentrations. These products may also be useful in managing constipation associated with the bile acid resins (BARs). 

The aggregation behavior of C21-DA salt in dilute electrolyte medium appears to resemble that of certain polyhydroxy bile salts (25,16). That C21-DA, with a structure quite different from bile acids, should possess solution properties similar to, e.g., cholic acid is not entirely surprising in light of recent conductivity and surface tension measurements on purified (i.e., essentially monocarboxylate free) disodium salt aqueous solutions, and of film balance studies on acidic substrates (IX) The data in Figure 3 suggest that C21-DA salt micelles Incorporate detergents - up to an approximate weight fraction of 0.5 -much like cholate Incorporates lecithin or soluble... 

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