Solid pharmaceutical composition

A solid oral preparation comprising (a) a first part comprising a compound, which is (5-methyl-2-oxo-1,3-dioxol-4-yl)methyl 2-ethoxy-1-{[2′-(5-oxo-4,5-dihydro-1,2,4-oxadiazol-3-yl)biphenyl-4-yl]methyl}-1H-benzimidazole-7-carboxylate potassium salt, and a solid pH control agent which is a combination of fumaric acid and a sodium ion donor, wherein the pH control agent provides a pH of 2 to 5 when dissolved or suspended in water at a concentration of 1% w/v at 25° C., the pH control agent is contained in a proportion of 0.1-5 wt % of the preparation, and (b) a second part comprising amlodipine besylate, wherein the first part and the second part are individually granulated, and wherein the solid oral preparation is a multi-layer tablet having (i) a first layer comprised of the first part, and (ii) a second layer comprised of the second part.