Compound of formula wherein R 1 denotes -R 3, -CH 2 -R 3 or -(C=O)-R 3; R 2 denotes Ar 2, Hetar 2 or C 3-7 -cycloalkyl; R 3 denotes Ar 3, Hetar 3 or C 3-7 -cycloalkyl; Ar 2 and Ar 3 denote independently from each other a mono- or bicyclic aromatic hydrocarbon system having 6 to 10 carbon atoms which system is unsubstituted or substituted with one or more identical or different substituents selected from the group consisting of C 1-6 -alkyl, C 1-6 -alkoxy, C 3-7 -cycloalkyl, -NH 2, N-(C 1-6 -alkyl)amino, N,N-(di-C 1-6 -alkyl)amino, halogen, -O-C 1-3 -alkylene-O-; Hetar 2 denotes an aromatic mono- or bicyclic, 4, 5, 6, 7, 8, 9 or 10 membered heterocycle having 1, 2 or 3 N and/or O and/or S atoms, which heterocycle is unsubstituted or substituted with one or more identical or different substituents selected from the group consisting of C 1-6 -alkyl, C 3-7 -cycloalkyl, (C 1-6 -alkyl)m-aryl wherein m is 0 or 1 and aryl is a mono- or bicyclic aromatic hydrocarbon system having 6 to 10 carbon atoms which aromatic hydrocarbon system is unsubstituted or substituted with one or more identical or different substituents selected from the group consisting of C 1-6 -alkyl, C 1-6 -alkoxy, C 3-7 -cycloalkyl, -NH 2, N-(C 1-6 -alkyl)amino, N,N-(di-C 1-6 -alkyl)amino, halogen; Hetar 3 denotes an aromatic mono- or bicyclic, 4, 5, 6, 7, 8, 9 or 10 membered heterocycle having 1, 2 or 3 N and/or O and/or S atoms, which system is unsubstituted or substituted with one or more identical or different substituents selected from the group consisting of C 1-6 -alkyl, C 3-7 -cycloalkyl, (C 1-6 -alkyl) n -aryl wherein n is 0 or 1 and aryl is a mono- or bicyclic aromatic hydrocarbon system having 6 to 10 carbon atoms which aromatic hydrocarbon system is unsubstituted or substituted with one or more identical or different substituents selected from the group consisting of C 1-6 -alkyl, C 1-6 -alkoxy, C 3-7 -cycloalkyl, -NH 2, N-(C 1-6 -alkyl)amino, N,N-(di-C 1-6 -alkyl)amino, halogen; or solvates, tautomers or stereoisomers thereof as well as the physiologically acceptable salts of each of the foregoing, including mixtures thereof in all ratios; with the proviso that the following compound of formula is excluded: a) 7-benzyl-8-(4-methoxyphenyl)-5,6,7,8-tetrahydro-tetrazolo[1,5-a]pyrazine. R 1 denotes -R 3, -CH 2 -R 3 or -(C=O)-R 3; R 2 denotes Ar 2, Hetar 2 or C 3-7 -cycloalkyl; R 3 denotes Ar 3, Hetar 3 or C 3-7 -cycloalkyl; Ar 2 and Ar 3 denote independently from each other a mono- or bicyclic aromatic hydrocarbon system having 6 to 10 carbon atoms which system is unsubstituted or substituted with one or more identical or different substituents selected from the group consisting of C 1-6 -alkyl, C 1-6 -alkoxy, C 3-7 -cycloalkyl, -NH 2, N-(C 1-6 -alkyl)amino, N,N-(di-C 1-6 -alkyl)amino, halogen, -O-C 1-3 -alkylene-O-; Hetar 2 denotes an aromatic mono- or bicyclic, 4, 5, 6, 7, 8, 9 or 10 membered heterocycle having 1, 2 or 3 N and/or O and/or S atoms, which heterocycle is unsubstituted or substituted with one or more identical or different substituents selected from the group consisting of C 1-6 -alkyl, C 3-7 -cycloalkyl, (C 1-6 -alkyl)m-aryl wherein m is 0 or 1 and aryl is a mono- or bicyclic aromatic hydrocarbon system having 6 to 10 carbon atoms which aromatic hydrocarbon system is unsubstituted or substituted with one or more identical or different substituents selected from the group consisting of C 1-6 -alkyl, C 1-6 -alkoxy, C 3-7 -cycloalkyl, -NH 2, N-(C 1-6 -alkyl)amino, N,N-(di-C 1-6 -alkyl)amino, halogen; Hetar 3 denotes an aromatic mono- or bicyclic, 4, 5, 6, 7, 8, 9 or 10 membered heterocycle having 1, 2 or 3 N and/or O and/or S atoms, which system is unsubstituted or substituted with one or more identical or different substituents selected from the group consisting of C 1-6 -alkyl, C 3-7 -cycloalkyl, (C 1-6 -alkyl) n -aryl wherein n is 0 or 1 and aryl is a mono- or bicyclic aromatic hydrocarbon system having 6 to 10 carbon atoms which aromatic hydrocarbon system is unsubstituted or substituted with one or more identical or different substituents selected from the group consisting of C 1-6 -alkyl, C 1-6 -alkoxy, C 3-7 -cycloalkyl, -NH 2, N-(C 1-6 -alkyl)amino, N,N-(di-C 1-6 -alkyl)amino, halogen; a) 7-benzyl-8-(4-methoxyphenyl)-5,6,7,8-tetrahydro-tetrazolo[1,5-a]pyrazine.