Factors affecting solubility

Later, Kato and coworkers found that the injection of cord factor also decreased the activity of some other diphosphopyridine nucleotide -linked dehydrogenases in mouse liver (such as lactic and a-glycerophosphoric dehydrogenase). The decreased enzymic activity was restored by homogenizing the liver of mice (treated with cord factor) with the sucrose extract of normal mouse-liver. The metabolic lesion caused by the injection of cord factor was assumed to be a decrease of a soluble factor affecting the activity of the succinic dehydrogenase system of mouse liver. 

A further factor affecting k- is the air-sea temperature difference. When the sea is colder than the air above it, the enhanced solubility of the gas in the water (relative to the air temperature) tends to increase kj. This will occur in summer in sub-polar waters and over upwelling regions. The opposite is also found, and much of the ocean equatorward of 45"" latitude is colder than the overlying air for much of the year. However, air-sea temperature differences are generally less than 2-3 "C so that this effect results in a less than 10% modulation of k- on average. 

Click Coached Problems for a self-study module on factors affecting solubility. 

Let us assume the solubility of oxygen does not affect on C or kLa, the factor affected on the oxygen uptake rate that is 12.5/3 = 4.167, then xmm is ... 

Reacetylation of chitosan under proper conditions leads to products having the same solubility. Experiments showed that the amount of acetic anhydride was the most important factor affecting the N-acetylation degree of the chitosan. The effect of the means of adding materials and the amount of solvent on the reaction could not be ignored [70]. 

Borel, R, Factors affecting intestinal absorption of highly lipophilic food microconstituents (fat-soluble vitamins, carotenoids and phytosterols), Clin. Chem. Lab. Med., 41, 979, 2003. 

Kuhn, A. T., Lesan, W. Setchell, D. (1983). Some further factors affecting the solubility of silicate cements. Journal of Materials Science letters, 2, 191-4. 

Drugs in Class II have low aqueous solubility (but high membrane permeability), and any factor affecting dissolution rate would be expected to have an impact on the absorption of such compounds. Factors that are noted in Fig. 11, such as fluid pH, volume and viscosity, and bile secretion (especially in response to fatty foods), might be expected to play a role in dissolution rate and thereby affect absorption. Compounds that fall into this class include carbamazepine, cyclosporin, digoxin, griseofulvin, and spironolactone. Food would be expected to exert a potentially significant affect on... 

Poly (vinyl acetate/alcohol) sizes are also described as water-soluble and are widely used, either alone or in combination with most of the other types, across the whole range of fibres and blends [169,171]. However, this category covers a wide range of commercial products, differing greatly in quality and ease of removal. Indeed, some are quite difficult to remove, thus necessitating careful selection [187]. Detailed studies of factors affecting the removal of water-soluble sizes, particularly poly(vinyl alcohol) types, have been published [188-190]. 

Solubility, dissolution rate, and intestinal permeability, are the major bio-pharmaceutic factors that affect the rate and extent of absorption of an oral drug product. Particularly for water insoluble drugs that have generally high membrane permeability (BCS Class II), dissolution, and dose are the most critical factors affecting the rate and the extent of oral absorption. 

House, J. E. (2007). Principles of Chemical Kinetics, 2nd ed. Elsevier/Academic Press, San Diego, CA. Chapters 5 and 9 contain discussions of factors affecting reactions in solution and the influence of solubility parameter of the solvent on reaction rates. 

The common ion effect (Chapter 3) is a further important factor affecting solubilities. Addition of A or B to the above system (equation (5.28)) will shift the equilibrium to the left and reduce the solubility of AB. In practice, this situation would arise when an excess of a precipitating reagent has been added to an analyte solution. Such an excess leads to the possibility of complexation reactions occurring which will tend to increase the solubility of AB. For example, when aluminium or zinc is precipitated by hydroxyl ions, the following reactions with excess reagent can occur... 

At least some of the cannabinoid-induced modulation of immune cells, and effects on host resistance to infection, are mediated directly by binding of cannabinoids to CBRs, particularly CBR2. Host immunity to microbes, however, involves many cell types, both immune and non-immune, as well as soluble factors including cytokines, chemokines, neurocytokines, and hormones related to the HP axis. It is therefore likely that a variety of cellular and molecular mechanisms whereby cannabinoids, including THC, affect immune function. 

Nearly 15 years after Patched s speech, we still face the same problems that he highlighted. Medicinal chemists often synthesize a potent molecule and find later that it has poor exposure in vivo, and thus poor efficacy. Poor exposure can be caused by many different factors. Most of the factors affecting exposure are commonly known by acronym ADME - absorption, distribution, metabolism, and excretion. A fifth factor, solubility, is also very important and is commonly considered to be part of ADME. 

The unique ability of crown ethers to form stable complexes with various cations has been used to advantage in such diverse processes as isotope separations (Jepson and De Witt, 1976), the transport of ions through artificial and natural membranes (Tosteson, 1968) and the construction of ion-selective electrodes (Ryba and Petranek, 1973). On account of their lipophilic exterior, crown ether complexes are often soluble even in apolar solvents. This property has been successfully exploited in liquid-liquid and solid-liquid phase-transfer reactions. Extensive reviews deal with the synthetic aspects of the use of crown ethers as phase-transfer catalysts (Gokel and Dupont Durst, 1976 Liotta, 1978 Weber and Gokel, 1977 Starks and Liotta, 1978). Several studies have been devoted to the identification of the factors affecting the formation and stability of crown-ether complexes, and many aspects of this subject have been discussed in reviews (Christensen et al., 1971, 1974 Pedersen and Frensdorf, 1972 Izatt et al., 1973 Kappenstein, 1974). 

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