Bioavailability testing

The Bioavailability Monograph for Erythromycin27 provides data for comparison of several manufacturers tablets of erythromycin. The criteria for bioavailability tests are discussed. 

Due to a combination of poor membrane permeability and metabolism at the site of absorption, rectal bioavailability of peptide and proteins is low. As in other mucosal bioavailability testing, insulin is the most studied polypeptide with respect to rectal absorption. 

This type of sampling protocol permits the quantification of mixing under a variety of different conditions. As we have mentioned, because core sampling provides large quantities of bed material in a reproducible manner, one can assay some of the samples and retain others for later analysis—e.g., to perform dissolution or bioavailability tests or for archival purposes. 

Dietary iron level does not seem to affect the efficiency with which dietary iron is converted into hemoglobin when ferrous sulfate (Table 1) or when ferric orthophosphate (Table 2) is the primary source of dietary iron. This is also true for white bread (Table 2) however, the source of the iron in the enriched flour used in the bread is unknown. That the efficiency of converting food iron into hemoglobin is not affected by dietary iron concentration is important to bioavailability testing because it is often difficult to formulate diets with precise amounts of iron, especially when foods are the sources of iron. 

Chemical Added to Food Level Added Food Iron Source Effect of Added Chemical on Iron Bioavailability Test Type (species) Reference ... 

Veng PP. Novel Approach to Bioavailability Testing Statistical Method for Comparing Drug Input Calculated by a Least-square Deconvolution Technique. J Pharm Sci 1980a 69 318-324. 

Wang, Y.P., Gan, Y., Zhang, X., 2011. Novel gastroretentive sustained-release tablet of tacrolimus based on self-microemulsifying mixture in vitro evaluation and in vivo bioavailability test. Acta Pharmacol. Sin. 32 (10), 1294—1302. 

There are a variety of field and laboratory analytical methods for soil lead measurement, depending on the type of analysis and its purposes in a given evaluation. Bulk soil lead measurement refers to measurement of the total lead content of the soil sample. Chemical speciation and micromineralogical studies in the context of human lead exposure variability refer to amounts of specific chemical forms of lead and their geochemical states. These studies are sometimes done in tandem with relative bioavailability testings, i.e., amounts of lead being absorbed under in vivo or in vitro simulation of in vivo conditions (Casteel et al., 2006) with respect to Pb source attribution. Stable isotopic analysis studies deal with the quantitative stratification of lead s stable isotopic composition into the four main stable isotopes lead-204, lead-206, lead-207, and lead-208 (Gulson et al., 1995, 1997). 

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