Oral bioavailability objective

Interestingly, increasing solubility is a pharmacokinetic as well as a pharmaceutical objective. Indeed, and as made explicit in the Biopharmaceutics Classification Scheme (BCS) [24], solubility is one of the main factors influencing oral absorption and hence oral bioavailability. 

However, the remaining problem was the administration route of the drug. Shortly before the Second World War, Inhoffen had prepared 17a-ethynyl-oestradiol, and had noticed that this derivative is surprisingly stable in the stomach. The initial objective of Inhoffen s synthesis was actually oestradiol-17-car-boxylic acid, which ought to have been produced by ethynylation and ozonoly-sis. Fortunately, the intermediate was also checked for its oral bioavailability. In fact, the carboxylic acid was only synthesised 50 years later and proved to be completely inactive. [24]... 

The objectives of fliis chapter are to examine the utility of the Caco-2 cell monolayer as a model for studies of the oral bioavailability of dietary flavonoids in humans and to outline the information that has been obtained with this system. 

Some medicines are normally given with food to reduce gastrointestinal side-effects in certain cases coadministration with food increases bioavailability of orally administered preparations. If the labelling states that the pharmaceutical product should be taken with food then a fed study should be used to assess bioequivalence. Fed state studies are also required in bioequivalence studies of modified release formulations. In these cases the objective is to select a meal that will challenge the robustness of the new multisource formulation to prandial effects on bioavailability (see 6.2.4). The test meal selected should take account of local custom and diet and should be consumed within 20 minutes. The product should be administered according to the protocol and within 30 minutes after the meal has been eaten. 

Another type of early clinical study may be conducted with the primary objective of establishing the bioavailability of a particular dosage form, concentration, and regimen. Bioavailability can be defined as the proportion of an administered dose that reaches the systemic circulation in an unchanged form. Maximum bioavailability results after an intravenous injection of the drug. In this case, the bioavailability is by definition 100%. When administered orally, however, a drug experiences first-pass metabolism, also called first-pass loss, before it reaches the systemic circulation. 

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