5-substituted-4-phenyl-5H-imidazo[4,5-c]pyridine derivatives

A compound of the formula ##STR11## or a pharmaceutically acceptable acid addition salt thereof, wherein R.sub.1 and R.sub.2 are each independently selected from the group consisting of hydro, straight or branched chain alkyl having 1 to 6 carbon atoms or cycloalkyl having 3 to 8 carbon atoms;

• R.sub.3 is a group substituted at one or more of the 2, 3, 5 or 6 positions of the phenyl ring said group being independently selected from hydrido, alkyl having 1 to 6 carbon atoms, halogen, alkoxy having 1 to 6 carbon atoms and thioalkyl wherein the alkyl has 1 to 6 carbon atoms;
• and
• R.sub.4 is a group substituted at one or more of the 2, 3, 4, 5 or 6 positions of the phenyl ring, said group being independently selected from hydrido, alkyl having 1 to 6 carbon atoms, thioalkyl wherein the alkyl has 1 to 6 carbon atoms, alkoxy having 1 to 6 carbon atoms and fluoro.