Pyridine derivatives

A method of treatment of a subject in need of an anti-ulcer agent or an anti-secretory agent, which comprises administering an effective amount of a compound selected from those having the general formula I ##STR13## and their pharmaceutically acceptable salts, wherein R.sub.1 is selected from hydrogen and lower alkyl;

• R.sub.2 is selected from (a) 2-aminophenyl;
• (b) 2-aminophenyl substituted at one to three other carbon atoms of the phenyl group by a substituent independently selected from "the class" consisting of halogen, trifluoromethyl, nitro, cyano, and groups having the formulae --O--Z--OR.sub.3, --SO--R.sub.3, --SO.sub.2 --R.sub.3, --O--Z--R.sub.3, --CO--R.sub.4, --CR.sub.5 .dbd.NR.sub.6, --NR.sub.7 --Z--R.sub.3 and --Z--R.sub.8 (where Z is --CO-- or --SO.sub.2 --;
• R.sub.3 is lower alkyl;
• R.sub.4 is selected from lower alkyl and aryl;
• R.sub.5 is selected from hydrogen, lower alkyl and aryl;
• R.sub.6 is selected from hydroxy and lower alkoxy;
• R.sub.7 is selected from hydrogen and --Z--R.sub.3 where Z and R.sub.3 are as defined above;
• and R.sub.8 is the same as R.sub.6 as defined above or --NR.sub.9 R.sub.10 where R.sub.9 and R.sub.10 are independently selected from hydrogen and lower alkyl;
• (c) phenyl substituted by one to three substituents independently selected from "the class" defined above subject to the proviso that one such substituent is present at a position selected from the 3- and 4-positions of the phenyl group;
• and (d) 2-[[(1-oxido-4-pyridinyl)carbonyl]amino]phenyl substituted at the phenyl group by one to two substituents independently selected from "the class" defined above subject to the proviso that one such substituent is at the 4-position of the phenyl group;
• and n is selected from 1 and 0 subject to the proviso that where n is 0 then R.sub.2 is selected from meanings (a) and (b).