This invention relates to novel triaryl derivatives, formula (I), a stereoisomer thereof or a mixture of its stereoisomers, or a pharmaceutically acceptable salt thereof, wherein all of X, Y and Z represent CH; or one or two of X, Y and Z represent N; and the others of X, Y and Z represent CH; and R1, R2, R3, R4 and R5. independently of each other, represent hydrogen, halo, tri-fluoromethyl, trifluoromethoxy, cyano, hydroxyl, alkoxy, alkyl, amino or sulfamoyl; or R1 and R2, together with the phenyl ring to which they are attached form an indolyl ring or a benzo-dioxolyl ring; and R3, R4 and R5 are as defined above; and R6 represents amino or nitro, which are found to be modulators of the nicotinic acetylcholine receptors. Due to their pharmacological profile the compounds of the invention may be useful for the treatment of diseases or disorders as diverse as those related to the cholinergic system of the central nervous system (CNS), the peripheral nervous system (PNS), diseases or disorders related to smooth muscle contraction, endocrine diseases or disorders, diseases or disorders related to neuro-degeneration, diseases or disorders related to inflammation, pain, and withdrawal symptoms caused by the termination of abuse of chemical substances.