When an oral product, usually a tablet or capsule, is taken, it instantly goes into the stomach (gastric compartment). The gastric environment can be described as an acidic (mostly HCl-based) aqueous solution (pH 1 to 3) with a churning (moving and mixing) process. Assuming a disintegrating type product, the product will disintegrate into solid particles/aggregates. Once in this disintegrated form, the drug will behave exactly like granules in a dilute acidic solution with mild stirring in a beaker or flask. In the case of non-disintegrating type tablets, the drug will be released or leaked-out from the unit into the acidic solution.
If the drug is soluble, it will move into the intestine as a solution, otherwise as a slurry or suspension. The important thing to note here is that the drug will move into the intestinal component with some delay. Here the acid solution or suspension will be mixed with a strong buffer turning the acidic liquid to basic, more accurately less acidic in the pH range of 5 to 7. Considering the variability in contents and the rates of the entrance of the two solutions i.e. slurry from the stomach and the buffer from the pancreas, it is almost impossible to determine or establish the pH of the soup accurately. However, it is a well-established fact that pH in this area of intestine ranges between 5 and 7. Therefore, for all practical and standardization purposes, one can use pH of 6, an average of 5 and 7.