The present invention provides an aqueous suspension-type pharmaceutical preparation that does not cause premature dissolution or absorption even when administered orally, exhibits gastric solubility corresponding to the drug characteristics, is capable of suppressing particle growth and particle aggregation, contains (1)–(4), and has a pH of 2.5–5.5. (1) A (3aR, 4S, 7R, 7aS)–2–{(1R, 2R)–2–[4–(1, 2–benzisothiazole–3–yl) piperazine–1–ylmethyl] cyclohexylmethyl} hexahydro–4, 7 – methano–2H–isoindole–1,3–dione, a pharmaceutically acceptable acid addition salt thereof, or a mixture of these； (2) at least one type of chloride selected from an inorganic chloride or a C4–12 quaternary ammonium chloride； (3) a dispersant； and (4) water.
