The invention provides an indazole derivative of formula (1), or a pharmaceutically acceptable salt or N-oxide thereof, wherein R1, R2, R3 and R4 are as defined herein. The indazole derivatives are capable of blockading voltage dependent sodium channels and they are useful in the treatment or prevention of normal tension glaucoma, multiple sclerosis, a motorneurone disease, stroke, spinal cord injury, Alzheimer's disease, Parkinson's disease or pain.
