Hi all.
I'm interested in a possibly trivial question.
What is the real significance of pH 4.5 and 6.8 dissolution media when analyzing solid dosage forms when we have immediate release in pH 1.2 media? After all, once the active substance enters the stomach, it completely dissolves in gastric juice. Having passed into solution, all the properties of crystals such as polymorphic form, particle size, etc., affecting the dissolution rate, are already, as it were, reset to zero? Why should we compare tablets in environments with pH 4.5 and 6.8? After all, a tablet or capsule cannot bypass the acidic environment of the stomach, where it is supposed to dissolve?
Although an immediate released tablet is designed to dissolve in gastric juice where pH is highly acidic but this pH can be altered due to prescence of food, nature of food and different patho-physiological conditions loke dyspepsia, ulcer etc. Before food arrives, the stomach normally has a pH between 5.0 and 6.0. In young and healthy adults it takes about 45 minutes before enough acid is generated to drop the pH to 3.0.
Therefor study is done at pH 4. and significance of study t pH 6.8 is to study behavior of tablet in duodenum.
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