The present invention provides an aqueous suspension-type pharmaceutical preparation that, even when administered orally, suppresses premature dissolution and absorption, has a relatively low risk of onset of unexpected side effects caused by temporary increase in concentration in the blood, and contains (1)–(4). (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) xantham gum； (3) a dispersant； and (4) water.
