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erties of the drug that influence absorption are solubility, distribution ratio (PC), pK, polarity, and the ability to form hydrogen bridges. Numerous in vitro methods can be used to estimate the absorption of the active ingredient. The following methods provide increasingly better approximations of in vivo conditions, but at the same time become increasingly more difficult and time-consuming to perform: |
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Static distribution ratio of the compound between water and an organic phase (octanol, cyclohexane, heptane), |
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Kinetic transport between two aqueous phases separated by a lipid model membrane, |
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Model absorption through a segment of isolated intestine in vitro, and |
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Model absorption through the oral membrane of a human subject |
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A drug product development program revolves around the recognition of the following factors: |
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1. The desired duration of activity, |
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2. The rate of release (delivery) over the desired duration of activity, and |
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3. The desired presence/absence of burst effect or immediate release of active ingredient. |
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