The present invention relates to piperidine derivatives of formula (I) ##STR1## wherein R.sup.1 is a C.sub.1-4 alkoxy group; R.sup.2 is ##STR2## R.sup.3 is a hydrogen or halogen atom; R.sup.4 and R.sup.5 may each independently represent a hydrogen or halogen atom, or a C.sub.1-4 alkyl, C.sub.1-4 alkoxy or trifluoromethyl group; R.sup.6 is a hydrogen atom, a C.sub.1-4 alkyl, (CH.sub.2).sub.m cyclopropyl, --S(O).sub.n C.sub.1-4 alkyl, phenyl, NR.sup.7 R.sub.8, CH.sub.2 C(O)CF.sub.3 or trifluoromethyl group; R.sup.7 and R.sup.8 may each independently represent a hydrogen atom, or a C.sub.1-4 alkyl or acyl group; x represents zero or 1; n represents zero, 1 or 2; m represents zero or 1; and pharmaceutically acceptable salts and solvates thereof; to processes for their preparation; and their use in the treatment of conditions mediated by tachykinins.