Compounds of formula (I) have muscarinic M3 receptor modulating activity; Formula (I) wherein A is an oxygen atom or group —N(R12)—; (i) R1 is C1-C6-alkyl or a hydrogen atom; and R2 is a hydrogen atom or a group —R5, —Z—Y—R5—Z—NR9R10; —Z—CO—NR9R10; —Z—NR9—CO—R5; or —Z—CO2H; and R3 is a lone pair, or C1-C6-alkyl in which case the nitrogen atom to which it is attached is a quaternary nitrogen and carries a positive charge; or (ii) R1 and R3 together with the nitrogen to which they are attached form a heterocycloalkyl ring, and R2 is a hydrogen atom; or a group —R5, —Z—Y—R5, —Z—NR9R10, —Z—CO—NR9R10, —Z—NR9—CO—R5, or —Z—CO2H, in which cases the nitrogen atom to which it is attached is a quaternary nitrogen and carries a positive charge; or (iii) R1 and R2 together with the nitrogen to which they are attached form a heterocycloalkyl ring, said ring being substituted by a group —Y—R5, —Z—Y—R5, —Z—NR9R10; —Z—CO—NR9R10; —Z—NR9—CO—R5; or —Z—CO2H and R3 is a lone pair, or C1-C6-alkyl in which case the nitrogen atom to which it is attached is a quaternary nitrogen and carries a positive charge; R4 is a group of formula (a), (b), (c) or (d); is an C1-C6-alkyl, aryl, aryl-fused-cycloalkyl, aryl-fused-heterocycloalkyl, heteroaryl, aryl(C1-C8-alkyl)-, heteroaryl(C1-C8-alkyl)-, cycloalkyl or heterocycloalkyl group, and the remaining variables are as defined in the specification.