There is provided an extended release pharmaceutical composition comprising from about 200mg to about 1000mg of entacapone or salts thereof, optionally with other pharmaceutically acceptable excipients. The invention also provides an extended release pharmaceutical composition comprising triple combination of from about 30mg to about 300mg of levodopa, 10mg to about 100mg of carbidopa and 200mg to about 1000mg of entacapone or salts thereof, optionally with other pharmaceutically acceptable excipients. The invention also relates to process of preparation of such compositions.