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Flashcards in Pharmaceutics 4 Deck (5)
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Weak acids are likely to be ________ in the stomach allowing them to be absorbed across lipophillic gastric mucosa

Note: in order for the unionised drug to partition into lipophillc environment, it must have a coefficient partition that favours this partitioning


Are weak bases ionised or unionised in the stomach?
How does this affect their absorption?

Ionised, making them less likely to be absorbed across lipophillic gastric mucosa
(More likely to be absorbed further down the GI tract where the pH is higher)


What three features make the small intestine particularly good for absorption? What do these added features mean in terms of absorption?

Large surface area
Long residence time
Excellent blood flow
This means that even ionised drugs can be partially absorbed in the small intestines


What is ion-pairing and how does it affect absorption?

Ionised drugs may combine with an oppositely charged ion in the small intestine, overall making the ion pair a neutral species that can permeate the gastric mucosa


What kind of molecules may be absorbed via active transport that others would not have been?

Ionised, or highly hydrophillic drug molecules
Some drug molecules resemble vital compounds and so may be actively absorbed