 The experimental drug AST-120 is composed of black, odorless spherical carbon particles in 2g sachets aluminum foil pouches. The placebo consists of microcrystalline cellulose spheres, Celphere CP-305 stained to match the appearance of AST-120, in 2g sachets aluminum foil pouches. Both AST-120 and placebo are oral taken by mouth preparations. Both are tasteless. To take the product, patients will tear open the sachet, drop the contents directly on their tongue and wash it down with 8 ounces of water. 