abstract |
The present invention provides compounds of formula (II):n and their pharmaceutically acceptable salts which are useful as histamine H 1 -antagonists. In formula (II) R 1 is C 1-4 alkyl, and R 2 is C 3-4 alkoxy, halogen. oramino: R 3 is a C 1-3 alkylene group: and R 4 is a 3-pyridyi. N-oxo-3-pyridyl, 6-methyl-3-pyridyl, N-oxo-6-methyl-3-pyridyl or 6-hydroxymethyl-3-pyridyl group. |