Therapeutic or preventive agent for nausea/vomiting

A therapeutic or prophylactic agent for preventing nausea and vomiting, the agent comprising a morphinan derivative represented by general formula (I):

• or a pharmacologically acceptable acid addition salt thereof as an active ingredient,
• [where R1 represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a cycloalkylalkyl group having 4 to 7 carbon atoms, a cycloalkenylalkyl group having 5 to 7 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 13 carbon atoms, an alkenyl group having 3 to 7 carbon atoms, a furanylalkyl group (where the alkyl moiety has 1 to 5 carbon atoms), or a thiophenylalkyl group (where the alkyl moiety has 1 to 5 carbon atoms);
• R2 and R3 are mutually independent and represent a hydrogen atom, a hydroxy group, an alkoxy group having 1 to 5 carbon atoms, an alkenyloxy group having 3 to 5 carbon atoms, an aralkyloxy group having 7 to 16 carbon atoms, an arylalkenyloxy group having 7 to 16 carbon atoms, an alkanoyloxy group having 2 to 6 carbon atoms, an alkenoyloxy group having 4 to 6 carbon atoms, an arylalkanoyloxy group having 7 to 16 carbon atoms, or an alkyloxyalkoxy group having 2 to 10 carbon atoms;
• R4 and R5 together form an —O—, —S—, or —CH2— bond, or are mutually independent and R4 represents a hydrogen atom, a hydroxy group, an alkoxy group having 1 to 5 carbon atoms, or an alkanoyloxy group having 2 to 6 carbon atoms and R5 represents a hydrogen atom;
• R6 represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an arylalkyl group having 7 to 16 carbon atoms, an arylalkenyl group having 7 to 16 carbon atoms, a hydroxyalkyl group having 1 to 5 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, a COOH— group, or an alkoxycarbonyl group having 2 to 6 carbon atoms;
• and -Q- moiety represents a group as follows:
• (where these structures may have one or more substituents selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a nitro group, an alkyl group having 1 to 5 carbon atoms, a hydroxyl group, an oxo group, an alkoxy group having 1 to 5 carbon atoms, a trifluoromethyl group, a trifluoromethoxy group, a cyano group, a phenyl group, a hydroxyalkyl group having 1 to 5 carbon atoms, an isothiocyanato group, SR8, SOR8, SOOR8, (CH2)rOR8, (CH2)rCOOR8, SOONR9R10, CONR9R10, (CH2)rNR9R10, and (CH2)rN(R)COR10 (where r is an integer from 0 to 5, R8 represents an alkyl group having 1 to 5 carbon atoms, R9 and R10 are mutually independent and represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a cycloalkylalkyl group having 4 to 7 carbon atoms), and where X represents an oxygen atom, sulfinur atom, a CH═CH, or NR7 group (where R7 represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 3 to 5 carbon atoms, an arylcarbonyl group having 7 to 13 carbon atoms, an alkylsulfonyl group having 1 to 5 carbon atoms, an arylsulfonyl group having 6 to 12 carbon atoms, an aralkylsulfonyl group having 7 to 13 carbon atoms, an aralkyl group having 7 to 16 carbon atoms, an arylalkenyl group having 7 to 16 carbon atoms, an alkanoyl group having 2 to 6 carbon atoms);
• Y represents a nitrogen atom or a CH group;
• and Z represents a bridge bond having 2 to 5 carbon atoms (where one or more carbon atoms may be replaced with a nitrogen, oxygen, or sulfur atom, and an aromatic or heteroaromatic ring having 5 to 12 carbon atoms or a cycloalkyl ring having 5 to 9 carbon atoms may be fused so as to share 2 or 3 skeletal carbon atoms)].