This invention concerns a compound of formula a N-oxide, a pharmaceutically acceptable addition salt, a quaternary amine and a stereochemically isomeric form thereof, wherein ring A represents phenyl, pyridyl, pyrimidinyl, pyridazinyl or pyrazinyl; R1 represents hydrogen; aryl; formyl; C1-6alkylcarbonyl; C1-6alkyl; C1-6alkyloxycarbonyl; C1-6alkyl substituted with formyl, C1-6alkylcarbonyl, C1-6alkyloxycarbonyl or C1-6alkylcarbonyloxy; X represents a direct bond; —(CH2)n3— or —(CH2)n4—X1a—X1b—; R2 represents an optionally substituted cyclic system; provided that N,3-diphenyl-3H-1,2,3-triazolo[4,5-d]pyrimidin-5-amine is not included; their use, pharmaceutical compositions comprising them and processes for their preparation.