Piperidine derivatives which are compounds of formula (I) ##STR1## wherein Ar.sub.1 and Ar.sub.2 independently represent a phenyl group optionally substituted by a halogen atom, a thienyl group or a pyridinyl group, A represents an alkylene group of 2 to 6 carbon atoms, X represents a CO group or a bond, R.sub.1 represents a hydrogen atom or an alkyl group of 1 to 4 carbon atoms, either R.sub.2 represents a hydrogen atom and R.sub.3 represents a hydrogen atom or a hydroxy group, or R.sub.2 and R.sub.3 together represent a bond, and R.sub.4 represents a hydrogen or halogen atom, or pharmaceutically acceptable acid addition salts thereof are useful as antiallergics and antipruritics.
吡啶衍生物是
化学式(I)的化合物
其中Ar.sub.1和Ar.sub.2分别表示苯基,可以选择地被卤素原子,
噻吩基或
吡啶基取代,A表示2至6个碳原子的烷基,X表示CO基团或键,R.sub.1表示氢原子或1至4个碳原子的烷基,R.sub.2表示氢原子和R.sub.3表示氢原子或羟基,或R.sub.2和R.sub.3一起表示键,R.sub.4表示氢原子或卤素原子,或其药学上可接受的酸加成盐可用作抗过敏和止痒药。