The present invention relates to a formulation for implantation having a novel constitution, which accomplishes controlled releases of active ingredients. The formulation comprises one of combinations (a), (b) and (c), as well as a carrier comprising a hydrophobic polymer, wherein the particle combination is dispersed into the carrier: (a) particles comprising an active ingredient, particles comprising a carbonate, and particles comprising a substance which is reacted with the carbonate in an aqueous solution to generate carbon dioxide (substance such as an acid); (b) particles comprising an active ingredient and a carbonate, and particles comprising a substance such as an acid; and (c) particles comprising a carbonate, and particles comprising an active ingredient and a substance such as an acid.