2 chf 2 u2014 ch 2 ch 2 cf 3 u2014 ch 2 cf 2 cf 3 and the like preferred lower alkyl substituted by halogen groups are groups having 1 4 carbon atoms the term u201c lower alkoxy u201d denotes a lower alkyl group as defined above which is attached via an oxygen atom for example methoxy ethoxy propoxy isopropoxy n butoxy i butoxy 2 butoxy t butoxy and the like preferred alkoxy groups are groups with 1 4 carbon atoms the term u201c lower alkoxy substituted by halogen u201d denotes a lower alkoxy group as defined above wherein at least one hydrogen atom is replaced by halogen preferred lower alkoxy substituted by halogen groups are groups having 1 4 carbon atoms the term u201c aryl u201d denotes an aromatic mono or bicyclic carbon ring system for example phenyl or naphthyl preferably phenyl the term u201c heteroaryl u201d denotes a five or six membered aromatic ring system containing one or two heteroatoms selected from o s and n for example isoxazolyl oxazolyl imidazolyl pyridinyl and the like preferably isoxazolyl u201c pharmaceutically acceptable u201d such as pharmaceutically acceptable carrier excipient etc means pharmacologically acceptable and substantially non toxic to the subject to which the particular compound is administered the term u201c pharmaceutically acceptable acid addition salts u201d embraces salts with inorganic.