Digestion drug absorption factors

After the tablet disintegrates in the stomach the drug molecules are dispersed in gastric juice with or without partially digested food, and normally only a small proportion will penetrate the gastric mucosa and enter the blood circulation - partly because the stomach presents only a small surface area for absorption. Drugs are absorbed across mucosal surfaces but there are factors which determine how much is absorbed and at what rate in any particular site. The first set of factors is to do with the dmg molecule itself. 

Since the vast majority of drugs are administered by mouth, it is important to consider factors that affect absorption of drugs from the gastrointestinal tract. See Figure 2.3 for a diagram of the digestive system. 

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