Pyrazine derivatives as blockers of epithelial sodium channels

A compound having the formula Ia ** ** Formula or salts, solvates or hydrates of the pharmaceutically acceptable, wherein R6 is - (C0-C6) -R 6a, where the alkylene linker is optionally substituted by one or more groups selected from C1-C3 alkyl, halo and OH; R6a is selected from H, a C3-C10 carbocyclic group, NR11R12, C (O) NR13R14, C6-C10 aryl, 5- to 6-membered heterocyclyl 5 to 6 members and a group of the formula P- (CH2) mQ, wherein each of the ring systems is optionally substituted by one or more substituents selected from the List Z; P is selected from a bond, -O-, -C (O) -, -C (O) O-, -NHC (> = N) NH- and -S (O2) -, - S (O2) NRa- , -NR a C (O) -, - NRa10 C (O) O-, -NR a S (O2) - and -NR a C (O) NR B; Ra and Rb are each independently selected from H, C1-C6-carbocyclic group, C3-C10 and - (C1-C3) -carbociclico C3-C10; Q is selected from H, C1-C6 alkyl, a carbocyclic group C3-C10, aryl C6-C10, 5- to 6-membered and 5- to 6-membered, where the carbocyclic groups, C6-C10 aryl, heteroaryl 5 to 6 membered and 5- to 6-membered are each optionally substituted by one or more substituents selected from the List Z; m is 0, 1, 2 or 3; R7, R8 and R10 are each independently selected from C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, a C3-C10 carbocyclic group, - (C1-C3) - carbocyclic C3-C10 aryl, C6- C10, 5- to 6-membered, 5- to 6-membered or a group of formula (CH2) da- (CH2) bB, where the carbocyclic groups, C6-C10 aryl, 5- to 6-membered heterocyclyl and 5 to 6 members are each optionally substituted by one or more substituents selected from the List Z; and wherein alkyl and alkylene groups are optionally substituted by one or more halogen atoms, OH groups or phenyl groups; or R7 and R8 together with the nitrogen atom to which they are attached form a heterocyclic group containing nitrogen 4- to 10-membered is optionally substituted by one or more substituents selected from the List Z; or R6 and R8, together with the atoms to which they are attached form a heterocyclic group containing nitrogen 4- to 10-membered is optionally substituted by one or more substituents selected from the List Z; A is selected from a bond, -O-, -C (O) -, -C (O) NR c, -C (O) O-, -OC (O) -, -NHC (> = N) NH- , -S (O2) -, -S (O2) NR c, - NR c C (O) -, -NR c C (O) O-, -OC (O) NR c, -NRcS (O2) -, - C (O ) NRcS (O2) -, -NR c C (O) NRd-, -NRc30 -, C6-C10 alkaryl, C3-C10- -carbociclilo, -heteroaryl 5 to 6-membered, -heterocyclyl 5 to 6-membered , aryl C6-C10-O-, -O-aryl, - O-carbocyclyl and C3-C10- C3-C10 -carbociclilo-O-, wherein C6-C10 aryl groups carbocyclyl, heteroaryl 5 to 6 members and heterocyclyl of 5-to 6-membered are each optionally substituted by one or more substituents selected from the List Z; B is selected from H, C1-C6 alkyl, a carbocyclic group C3-C10, NRxRy, C (O) ORz35, aryl, 5- to 6-membered and 5- to 6-membered, where the carbocyclic groups, C6 C10, 5- to 6-membered heterocyclyl and 5- to 6-membered of each are optionally substituted by one or more substituents selected from the List Z; d is 1, 2, 3, 4, 5, 6 or 7; b is 0, 1, 2 or 3; Rc, Rd, Rx and Ry are each independently selected from H, C1-C6-carbocyclic group, C3-C10 and - (C1-C3) -carbociclico C3-C10; Rz is H or C1-C6 alkyl; R9 is H or C1-C6 alkyl; or R6 and R9, together with the carbon atoms to which they are attached, form a C3-C10 carbocyclic group or a heterocyclyl group 4- to 10-membered or 5 to 6 members, wherein each ring systems it is optionally substituted by one or more substituents selected from the List Z; R11 is selected from H, C1-C6 alkyl, a carbocyclic group and C3-C10 - (C1-C3) -carbociclico C3-C10; R12 is selected from H, C1-C6 alkyl, C3-C10 carbocyclic group, - (C1-C3) -carbociclico C3-C10, - C (O) C1-C6 alkyl, -C (O) C3-C10 carbocyclic , -C (O) (C1-C3) -carbociclico C3-C10, -C (O) (CH2) x C6-C10 aryl, - C (O) (CH2) x 5- to 6-membered -C (O) (CH2) x 5- to 6-membered, -C (O) O, C (O) O-aryl C6-C10, (CH2) x C6-C10 aryl, (CH2) x 5- to 6-membered - (CH2) x 5- to 6-membered, wherein each of the ring systems is optionally substituted by one or more substituents selected from the List Z; R13 is selected from H, C1-C6 alkyl, a carbocyclic group and C3-C10 - (C1-C3) -carbociclico C3-C10; R14 is selected from H, C1-C6 alkyl, C3-C10 carbocyclic group, - (C1-C3) -carbociclico C3-C10, - (CH2) z C6-C10 aryl, (CH2) z heteroaryl 5 to 6 members and (CH2) z 5- to 6-membered, wherein each of the ring systems is optionally substituted by one or more substituents selected from the List Z; x is 0, 1, 2 or 3; z is 0, 1, 2 or 3.