They act as antagonists of muscarinic receptors, processes for the preparation thereof, compositions comprising them and their therapeutic use. Claim 1: A compound characterized in that it is of general formula (1) where R1 is selected from the group consisting of C1 alkyl -6, aryl, C3-8 cycloalkyl, C1-6 arylalkyl and heteroaryl, and is optionally substituted with one or more substituents selected from the group consisting of halogen atoms, OH, oxo, SH, NH2, NO2, CN, CONHR5 , CON (R5) 2, NHCOR5, COR5, CO2R5, C 1-6 alkylsulfanyl, C 1-6 alkylsulfinyl, C 1-6 alkylsulfonyl, C 1-6 alkyl, C 1-6 haloalkyl, C 1-6 alkoxy and C 1-6 haloalkoxy；R2 is H or C1-6 alkyl optionally substituted with one or more substituents selected from the group consisting of halogen atoms, OH, oxo, SH, NH2, NO2, CN, CONHR5, CON (R5) 2, NHCOR5, COR5, CO2R5, C 1-6 alkylsulfanyl, C 1-6 alkylsulfinyl, C 1-6 alkylsulfonyl, C 1-6 alkyl, C 1-6 haloalkyl, C 1-6 alkoxy and C 1-6 haloalkoxy； R3 is H or is selected from the group consisting of C1-6 alkyl, aryl, C3-8 cycloalkyl and heteroaryl, and is optionally substituted with one or more substituents selected from the group consisting of halogen atoms, OH, oxo, SH, NH2, NO2, CN, CONHR5, CON (R5) 2, CO2R5, C1-6 alkylsulfinyl, C1-6 alkylsulfonyl, C1-6 alkyl,C1-6 haloalkyl, C1-6 alkoxy and C1-6 haloalkoxy； R6 represents a group of formulas (2) to (5) where m = 1, 2 or 3； n = 1, 2 or 3； A- is a physiologically acceptable anion； R4 is a group of the formula: --- (CH2) p --- P --- (CH2) q --- W, where p is 0 or an integer between 1 and 4； q is 0 or an integer between 1 and 4； P is a heteroaryl, and is optionally substituted with one or more substituents selected from the group consisting of halogen atoms, OH, oxo, SH, NO2, CN, CON (R5) 2, NH2, NHCOR5, CO2R5, C1- alkylsulfanyl 6, C 1-6 alkylsulfinyl, C 1-6 alkylsulfonyl, C 1-6 alkyl and C 1-6 alkoxy； W is selected from the group consisting of aryl, C3-8 cycloalkyl and heteroaryl,and is optionally substituted with
