4-(biphen-3-yl)-1H-pyrazolo[3,4-c]pyridazine derivatives of formula (I) as GABA receptor modulators for use in the treatment of epilepsy and pain

A compound according to formula (I)

• or a pharmaceutically acceptable salt thereof, wherein
• X is selected from —S(O)2— and —C(O)—;
• R1 is selected from (C2-C4)alkyl, (C3-C5)cycloalkyl and methyl-substituted (C3-C5)cycloalkyl;
• R2 is selected from H, F, Cl, OCH3 and CN;
• R3 is selected from H, F, CHF2, OCH3 and CN;
• when X is —S(O)2— then
• R4 is selected from (C1-C4)alkyl, (C3-C5)cycloalkyl, NH2 and NH(C1-C4)alkyl, and R5 is H;
• or
• R4 and R5 together are —CH2CH2— or —N(CH3)CH2—;
• and
• when X is —C(O)— then
• R4 is selected from NH2 and NH(C1-C4)alkyl, and R5 is H;
• or
• R4 and R5 together are —N(CH3)CH2—.