Drugs are small molecules that often occur in either a neutral or a charged form, depending on pH. For example, aspirin can be either neutral or lose a proton to be negatively charged. When aspirin is charged, it does not diffuse well into the body. pH varies in the gastrointestinal track. Since the stomach has a low pH (pH=3), it has a larger concentration of neutral aspirin (10-3 M), while the small intestine (pH=6) has a smaller neutral aspirin concentration (10-6 M). For the following, assume that the neutrally charged aspirin molecule has a diffusion coefficient through the cell of 1 x 10-6 cm2/s. C) We’d like to figure out where in the body aspirin is absorbed as determined by its diffusion rate. If the small intestine has a surface area 50 times that of the stomach, what is the ratio of the diffusion rates in the stomach compared to the small intestine? D) In which part of the GI tract is most of the aspirin absorbed?
Drugs are small molecules that often occur in either a neutral or a charged form, depending on pH. For example, aspirin can be either neutral or lose a proton to be negatively charged. When aspirin is charged, it does not diffuse well into the body. pH varies in the gastrointestinal track. Since the stomach has a low pH (pH=3), it has a larger concentration of neutral aspirin (10-3 M), while the small intestine (pH=6) has a smaller neutral aspirin concentration (10-6 M). For the following, assume that the neutrally charged aspirin molecule has a diffusion coefficient through the cell of 1 x 10-6 cm2/s.
C) We’d like to figure out where in the body aspirin is absorbed as determined by its diffusion
rate. If the small intestine has a surface area 50 times that of the stomach, what is the ratio
of the diffusion rates in the stomach compared to the small intestine?
D) In which part of the GI tract is most of the aspirin absorbed?
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