PSYC 455 Lecture Notes - Lecture 3: Aniline, Acid Dissociation Constant, Aspirin
17 Feb 2018
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Aspirin (weak acid) with a pka of 3. 5: 61% is absorbed in the stomach and 35% is absorbed in the intestines: Since our weak acid is going toward an acidic environment (i. e. the stomach), it becomes less ionized (i. e. Since our weak acid is going toward an acidic environment (i. e. the stomach), it becomes less ionized (i. e. more fat-soluble) and so it is mostly absorbed in that environment (the stomach). Aniline (weak base) with a pka of 4. 6: Becomes water-soluble when it moves to a more acidic environment (e. g. , the stomach absorbs very little aniline; 6%). Mostly absorbed in the intestine (50%) because it becomes fat- soluble when it moves toward an basic environment (recall, intestine has a ph of 5-6): Aniline is therefore very fat-soluble once it gets to the blood stream and so disperses well. Very fat-soluble so absorbed everywhere: distribution, transmembrane processes (i. e. how drugs cross the cellular membrane/phospholipid bilayer) include, passive diffusion:
