Intestinal drug absorption solubility

Fig. 7.5. The Biopharmaceutics Classification System (BCS) provides a scientific basis for predicting intestinal drug absorption and for identifying the rate-limiting step based on primary biopharmaceutical properties such as solubility and effective intestinal permeability (Pefr). BCS serves as a product control instrument. The BCS divides drugs into four different classes based on their solubility and...

Let us conclude this section by proposing that provided that the drug is sufficiently soluble in the gastrointestinal fluids, the complex process of intestinal drug absorption can often be satisfactorily described by focusing on passive transport across the cell membrane, and that the development of models that predict passive transcellular permeability is particularly important. Such models are the focus of the remaining part of this chapter. 

Mrozek et al. synthesized fourteen acyloxy derivatives of 5(S-cholic acid as novel potential transdermal penetration enhancers and intestinal drug absorption modifiers (Figure 49.6). Nontoxic bile acid/salt derivatives (as amphiphilic compounds) are used widely in drug formulations as excipients and can influence gastrointestinal solubility, absorption, and chemical/enzymatic stability of drugs. Transdermal penetration enhancers are special pharmaceutical excipients that interact with skin components to increase the penetration of drugs into blood circulation after topical application. Structure confirmation of all generated compounds was accomplished by H NMR, NMR, IR, and mass spectrometer (MS) spectroscopy. 

GI absorption of many poorly soluble drugs depends on small intestinal transit, as demonstrated for ketoprofen, nifedipine, haloperidol, miconazole, and others. Small intestinal transit rate and transit time become important factors in drug absorption, particularly when the ratio of dose to solubility is high and dissolution rate is very slow or when the drug is... 

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