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** Gastrointestinal Dissolution and Absorption of Drugs **

When Fick s first law is applied to a membrane, the absorption of a drug across the GI mucosal surface under sink conditions can be written as [Pg.34]

The absorption number (An) is the ratio of permeability (Peff) and the intestinal radius (P) multiplied by the residence time (t,.es), which can be interpreted as the effective absorption rate constant (t. ) times the residence time [Pg.34]

The dissolution number (Dn) is the ratio of the residence time and the dissolution time (toiss)j which comprises the equilibrium solubility (Cs), diffusivity (D), density (p), the initial particle radius (r0), and the intestinal residence time (tres) [Pg.35]

Finally, the dose number (D0) is the ratio of dose to dissolved drug [Pg.35]

** Gastrointestinal Dissolution and Absorption of Drugs **

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