Estimation of the gastric residence time of magnetic dosage forms using the Heidelberg capsule

A new method for determining the gastrointestinal transit of magnetic dosage forms under the influence of an extracorporal magnet has been developed. A magnetic model dosage form was constructed consisting of small magnets attached to a pH-telemetering capsule (Heidelberg capsule). The transmission of the pH measurements was not affected by the magnetic field. The force of attraction of the magnetic model dosage form by the external magnet was characterised. In an in vivo study in five subjects the transmitted pH values showed indirectly that the gastric residence time of the magnetic model dosage form was prolonged significantly in the presence of an extracorporal magnet (t-Test, paired data, p < 0.05).