[Comparative dissolution test of modified release pharmaceutical products for potassium replacement].

Introduction: Oral potassium replacement is still inevitable. To reduce the irritation of the gastric and intestinal mucosa, pellet and matrix based formulations ensuring extended release of potassium chloride are used. The dissolution tests may help to understand the in vivo steps of the release of potassium chloride and the absorption of potassium.

Aim: Using dissolution tests extended to 12 hours the authors evaluated potassium chloride release characteristics of pellet and matrix tablet based formulations used for potassium replacement.

Method: The tests were performed in line with the CPMP/EWP/QWP/1401/98 guideline at nine time points (0, 1, 2, 3, 4, 5, 7, 9 and 12 hours) in three dissolution media (0.1 M hydrochloric acid, pH 1.2; acetate buffer, pH 4.5; phosphate buffer, pH 6.8).

Results: Similar results were found in all three dissolution media.

Conclusions: It is conceivable, that the release of potassium chloride begins already in the stomach (pH = 1.2) and at an average speed of gastrointestinal transit - in about 6-7 hours - 80% of the potassium chloride content of both formulations is dissolved by the time of the entrance to the large bowel. It seems likely, that in vivo in the proximal section of the gastrointestinal tract more potassium chloride is dissolved out of the matrix based formulation, than from the pellet based one. Both formulations meet the clinical requirements of the effective potassium chloride release.