Solventless-mixing tablet coating technique using a V-shaped blender; investigation using methyl methacrylate and...

Our aim was to investigate the feasibility of a tablet coating mixing technique using a V-shaped blender to produce coated tablets by mixing only tablets and polymer powder. Tablet coating was achieved as follows. First, polymethacrylate latex was freeze-dried to prepare a coating powder. Second, tablets and polymer powder were mixed using the blender, yielding coated tablets. Two types of coating powder, composed of colloidal or non-colloidal particles of the same polymer, were prepared and used in the mixing treatment. Colloidal powder was rapidly pulverized due to impact by falling tablets in the blender and adhered to tablet surface. The powder on tablets was easily consolidated due to compression by tumbling tablets, yielding a polymer layer that can suppress drug release after curing. In contrast, non-colloidal powder was insufficiently pulverized and densified, and its deposition did not occur. Therefore, tablets are mechanically coated using a V-shaped blender by using colloidal polymer powder with high grindability and compactability. The impact rose by increasing rotation speed of the blender and promoted deposition of the polymer. Appropriate collision impacts of tablet-tablet and tablet-wall are required for successful tablet coating, although too intense impacts lead to tablet breakage and removal of the membrane.