Piperidine derivatives

A pharmaceutical composition comprising a therapeutically effective amount of a compound of formula I

• wherein
• R1 is hydrogen, lower alkyl, CD3,—(CH2)n—CHO, —(CH2)n—O-lower alkyl, —(CH2)n—OH, —(CH2)n-cycloalkyl or heterocycloalkyl;
• R2 is hydrogen, halogen, hydroxy, lower alkyl, di-lower alkyl, —OCH2—O-lower alkyl, or lower alkoxy;
• or the piperidin ring together with R2 forms 4-aza-spiro[2.5]oct-6-yl;
• Ar is phenyl substituted by one or two CF3 groups and optionally substituted by one or two substituents selected from halogen, lower alkyl, lower alkyl substituted by halogen, lower alkoxy halogen, cycloalkyl, lower alkoxy, S-lower alkyl, heteroaryl, heterocycloalkyl, and phenyl optionally substituted by R′, to give no more than three substituents total on Ar;
• R′ is lower alkyl, lower alkoxy, lower alkoxy substituted by halogen, or heteroaryl;
• R is phenyl optionally substituted by one or two R′;
• and
• n is 0, 1 2 or 3;
• or a pharmaceutically acceptable acid addition salt, racemic mixture, enantiomer, or optical isomer thereof and a pharmaceutically acceptable carrier.