Gastrointestinal degradation

Improvement in aqueous solubility, stability, permeability and bioavailability of ingredients protection against oxidation and gastrointestinal degradation (Bhardwaj et al, 2005 Chen et al, 2006a Semo et al, 2007 McClements et al, 2008, 2009 Augustin and Hemar, 2009) provision of sustained release lymphatic absorption of filled nanoparticles via gut-associated lymphoid tissue that avoids first-pass metabolism in liver (Delie, 1998 Hussain et al, 2001 Ratnam et al, 2006)... 

GBL was found to hydrolyse rapidly in plasma, with a half-life of approximately 1 minute. In spite of this rapid biotransformation, oral activity of GBL was almost identical to that achieved after intravenous administration of GHB. Apparently, GBL is not subjected to any of the processes which decrease peak plasma concentrations, viz gastrointestinal degradation, capacity-limited transport and first-pass metabolism. The use of lactone analogs as a general approach to improve the bioavailability and/or rate of absorption of other hydroxy-acids, e.g. prostaglandins, has, however, not been tested. 

The transdermal route of agent administration could be advantageous in the delivery of many therapeutic proteins, because proteins are susceptible to gastrointestinal degradation and exhibit poor gastrointestinal uptake, and transdermal devices are more acceptable to patients than injections. 

Polymeric microparticles have been studied and developed for several years. Their contribution in the pharmacy field is of utmost importance in order to improve the efficiency of oral delivery of drugs. As drug carriers, polymer-based microparticles may avoid the early degradation of active molecules in undesirable sites of the gastrointestinal tract, mask unpleasant taste of drugs, reduce doses and side effects and improve bioavailability. Also, they allow the production of site-specific drug targeting, which consists of a suitable approach for the delivery of active molecules into desired tissues or cells in order to increase their efficiency. 

Figure 34-8. Formation of uric acid from purine nucleosides byway of the purine bases hypoxanthine, xanthine, and guanine. Purine deoxyribonucleosides are degraded by the same catabolic pathwayand enzymes,all of which existin the mucosa of the mammalian gastrointestinal tract.

Gout is caused by an abnormality in uric acid metabolism. Uric acid is a waste product of the breakdown of purines contained in the DNA of degraded body cells and dietary protein. Uric acid is water soluble and excreted primarily by the kidneys, although some is broken down by colonic bacteria and excreted via the gastrointestinal tract. 

The more rapidly the drug is absorbed, the less chance there is of drug degradation or interactions with other materials present in the gastrointestinal tract. 

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