Application of a biomagnetic measurement system (BMS) to the evaluation ofgastrointestinal transit of intestinal pressure-controlled colon delivery capsules (PCDCs) in human subjects

Purpose. For determination of the transit rime through various parts of the gastrointestinal (GT) tract, we developed a method that provides the locat ion of disintegration and drug release. This method involves GI magnetomark ergraphy (GIMG) using a 129-channel Shimadzu vector biomagnetic measurement system (BMS). Methods. To magnetically label the pressure-controlled colon delivery capsu le (PCDC) containing 75.0 +/- 0.5 mg of caffeine as a tracer drug, small ca psule caps containing 90 mg of ferric oxide powdered magnetite (Fe2O3) were attached to PCDCs. After orally administration to fasted human volunteers, saliva samples were collected hourly and salivary caffeine concentration w as measured. At the same time, locations of the magnetic PCDC were detected by EMS just after the PCDCs were magnetized with the coils of a magnetic r esonance imaging (MRT) system. The magnetic field distributions were analyz ed and the estimated positions were shown on the MRI picture of the same su bject's abdominal structure. Results;. We magnetized PCDC with permanent magnets or an electromagnet bef ore ingestion and the estimated locations of PCDC in the GI tract exhibited high estimation error. In order to increase the precision of estimated loc alization of PCDCs, PCDCs were magnetized within the coils of the MRI. As a result these PCDCs had strong magnetic dipoles that were parallel to the s ensor unit of EMS in every measurement, and therefore the spatial resolutio n of the PCDC's two-dimensional positions in the organs of the GI tract was within a range of several Conclusions. GIMG is a powerful tool for the study of colon delivery effici encies of PCDCs. The main advantage of GIMG is the capability to obtain eve n more detailed knowledge of the behavior and fate of solid pharmaceutical formulations during GI passage.