Indole derivatives as 5-HT receptor antagonist

A compound of formula (I) or a salt thereof:

• wherein:
• P1 is phenyl;
• P2 is pyridyl;
• A is a bond, or a group OCH2, or O;
• R1 and R2 groups are each independently hydrogen, C1-6 alkyl optionally substituted by NR12R13, C2-6alkenyl, C2-6alkynyl, C1-6alkylthio, cyano, nitro, halogen, CF3, C2F5, NR12R13, CONR12R13, NR12COR13, S(O)pNR12R13, CHO, OCF3, SCF3, COR14, CH2OR14, CO2R14 or OR14 where p is 1 or 2 and R12, R13 and R14 are independently hydrogen, C1-6alkyl, phenyl, napthyl, or phenylC1-6alkyl;
• n and m are independently 0, 1 or 2;
• R3 is hydrogen or C1-6alkyl;
• R4 is a group of formula (iii):
• in which:
• R6 and R7 are independently hydrogen, C1-6 alkyl optionally substituted by one or more fluorine atoms, C2-6alkenyl, C3-6cycloalkyl, C3-6cycloalkyl, C1-6alkoxy, C2-6alkynyl, C3-6cycloalkyloxy, C3-6cycloalkyl-C1-6alkyl, C1-6alkylthio, C3-6cycloalkylthio, C3-6cycloalkyl-C1-6alkylthio, C1-6alkoxy, hydroxy, halogen, nitro, OCF3, SCF3, SO2CF3, SO2F, formyl, C2-6alkanoyl, cyano, phenyl, NR12R13, CONR12R13 or CO2R14 where R12, R13 and R14 are as defined for R1.