Bioavailability in-vivo

Technical information based on in vivo standards and specifications are generally incorporated in various official compendia. Hence, in order to record a legitimate assessment of bioavailability, in vivo test is an absolute necessity and the relative data obtained therefrom should form an integral part of the standard specifications in the offcial standard. 

To be added in cases of indications for relevance and bioavailability In vivo bioassays with relevant exposure conditions, routes and endpoints Prolonged ELS and metamorphosis In vivo bioassays with sediment extracts In vitro bioassays specific mechanisms Internal effect levels Specific chemicals (e.g. PFACs, HBCDs, PBDEs) ELS not longer than free feeding Chemicals that only are toxic in high concentration (narcotics, nanoparticles) Chemical analysis of lipophillic POPs in water... 

The successful application of food-grade biopolymers in the formulation of the next generation of smart delivery systems requires sound insight into the various intermolecular and colloidal interactions involved in the food matrix, along with some knowledge of the bioavailability in vivo. Furthermore, the impact of incorporated nutraceuticals on all the properties of a formulated functional food — appearance, physical/chemical stability, texture, mouthfeel, taste, flavour, bioavailability, and health impact — need to be simultaneously considered and addressed in order to achieve a balanced and acceptable solution for consumers. 

Sintov,A. C.,and Shapiro, L. (2004), New microemulsion vehicle facilitates percutaneous penetration in vitro and cutaneous drug bioavailability in vivo, J. Controlled Release, 95(2), 173-183. 

The main observations to be made from the tested correlations are that the observed differences in the bioavailability in vivo were also found in vitro. In addition, the various relationships were found to be suitable to discriminate between the formulations. In this case, we might be able to use them as a control for development and production, but new investigation and the test of the predictive power of the relationship must be investigated. 

Unfortunately, only relatively few of the many papers published on povidone deal with its influence on bioavailability in vivo. However, where results are available, they almost always show an improvement in bioavailability. Figs. 49 to 51 show the effect of coprecipitation with povidone on the bioavailability of different active substances administered by different routes. Fig. 49 shows, as a typical example, the oral bioavailability of a nifedipine coprecipitate in the rat, Fig. 50 shows the rectal bioavailability of a phenobarbital coprecipitate in rabbits, while Fig. 51 shows the effect of a hydrocortisone coprecipitate on the human skin after percutaneous administration. In all three cases, the same dose of the pure active substance without povidone was applied for reference. 

Table 79. Publications on the improvement in bioavailability in vivo solid solutions and dispersions in povidone through the use of ...

Wiseman, S., Mulder, T., and Rietveld, A. 2001. Tea flavonoids Bioavailability in vivo and effects on cell signaling pathways in vitro. Antiox. Redox Signal 3 1009-21. 

In vitro dissolution studies are used to assess product quality. In ideal circumstances in vitro dissolution rate should correlate with in vivo bioavailability. A dosage form with a rapid dissolution rate is likely to have a rapid rate of drug bioavailability in vivo. However, bioavailability is not only dependent on the dissolution of the drug product, but also the permeability and solubility of the drug substance. When an in vitro-in vivo correlation is available, the in vitro test can serve as an indicator of how the product will perform in vivo. 

Kalia, Y.N., Alberti, I., Naik, A., and Guy, R.H., 2001, Assessment of topical bioavailability in vivo, the importance of stratum corneum thickness. Skin Pharmacol. Appl. Skin Physiol, 14, 82-86. 

This continues to be an active research area, as evidenced by the book on infant nutrition by Chandra [15], and reviews on bioavailability in vivo and in vitro [436] and The hormonal regulation of manganese metabolism [437]. Other aspects covered include bioavailability [438], dietary interactions [439], general nutrition [440], and growth rate and metabolism [441]. 

Campisi, G. Giannola, L.I. Florena, A.M. De Caro, V. Schumacher, A. Gottsche, T Paderni, C. Wolff, A. Bioavailability in vivo of naltrexone following transbuccal administration by an electronically-controlled intraoral device A trial on pigs. J. Contr. Release 2010,145 (3), 214-220. 

The rate and extent (percentage) of absorption of a substance through the skin (bioavailability) in vivo are usually determined by measuring the total radioactivity in blood or excreta following a topical application... 

Table 135 Tlavonoid paradox between their biological activity in vitro and bioavailability in vivo.

Oral bioavailability in vivo is dependent on both permeability and first pass metabolism that may occur in the intestine and liver. The intrinsic clearance per pmol CYP is assumed to be the same in human liver microsomes (HLM) as in intestinal microsomes (Yang et al. 2004), whereas CYP3A abundance represents the total amount of enzyme, 70,000 pmol in the gut (Paine et al. 1997). The abundance of CYP3A in the gut is calculated using (32). 

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