Development of an abdominal magnetic resonance (MR) contrast agent formulation with Oral Magnetic Particles (OMP,...

A formulation for fast dispersible granules with the magnetic resonance (MR) contrast agent, Oral Magnetic Particles (OMP), was developed. The formulation contained viscosity-increasing agents (xanthan gum and a mixture of microcrystalline cellulose and sodium carboxymethylcellulose). The granules were dispersed easily in water when stirred by hand and became a viscous OMP suspension with apparent homogeneity, but does not form granule aggregates (lump), within 10 min. The dispersibiility was greatly affected by the binder type and addition of disintegrant. Hydroxypropylcellulose and low-substituted hydroxypropylcellulose were preferable. The preparation method to incorporate OMP into the granules also greatly influenced the dispersibility of the granules. A fluidized bed granulation of the base granules containing additives and subsequent coating of OMP onto the granules was eventually utilized. The formulation was able to control the viscosity of the suspension by regulating the content of viscosity-increasing agent while maintaining dispersibility. The developed formulation gave a good MR contrast image in rats and no magnetic susceptibility artifact was observed.