Absorption influential factors

Many physiological aspects affect drug absorption from the rectum (Table 7.1). Influential factors include the pH of the rectal contents, state of the mucus layer, volume and viscosity of rectal fluid, luminal pressure from the rectal wall on the dosage form, enzymatic and microbacterial degradation by rectal epithelium, presence of stools, and venous drainage differences within the rectosigmoid regions. 

TABLE 7.1 Influential Factors on Rectal Drug Absorption from Suppository ... 

In this chapter, medicinal aspects of vanadium compounds acting on the cellular/molecular level (Section 5.1) and the interaction of vanadium with proteins (including, to some extent, interferences with protein substrates and DNA Section 5.2) will be covered. Since beneficial and adverse effects can go hand and hand, or are dose dependent and/or controlled by a multitude of influential factors, this coverage also considers aspects directed towards absorption, distribution and the toxic implications of vanadium, some of which have already been addressed briefly in the Introduction. A comprehensive treatise on nutritional, environmental and toxicological aspects is beyond the scope of this book. The interested reader is referred to review articles in books and journals mentioned and recommended in the section Further Reading at the end of Chapter 1. 

Starting from the 1960s, many scholars made indoor and field test and research on the law of transport of solute and radioactive elements in single fracture systems (Moreno, 1982 Novakowski, 1994 Hadamman, 1991) and there have been large number of numerical simulation research results (Noorishad and Mehran, 1982 Christopher, 1995) considering influential factors such as diffusion of solute from fracture to matrix, the absorption action of fracture surface, variation of water flow speed and dispersivity and radioactivity decaying. However, all simulations hitherto made assume that tracer transports in... 

The small intestine is the most important organ for drug absorption in the gastrointestinal tract. The surface area of the intestine is approximately 200 m (Caspary, 1992) because of the presence of well-developed vilh. Collapsibility, drug solubility, and membrane permeability are the most influential factors in determining Fa- Solubility in aqueous solution is a critical factor in optimizing Fa (Ku, 2008). 

The intestinal wall is optimized to absorb fluids and nutrients while keeping away different xenobiotics. Which factors, from a theoretical point of view, are the most influential in intestinal absorption ... 

The acidic properties and, therefore, the acid-catalysis of metal salts sometimes vary in a complex manner, depending on several factors. The absorptivity and homogeneity, as well as the reduction and hydrolysis of polyanions, are particularly influential. When the salts are water-soluble (group A), the catalytic activity for bulk-... 

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