P-phenylenediamine derivative as potassium channel regulator and preparation method and medical application thereof

A method for treating of disorder or condition in response to abnormal ion flow in potassium channel, comprising administering a compound of formula A or a pharmaceutically acceptable salt thereof into a subject in need thereof;

• wherein:
• ring B is
• ring A is a thiophene ring;
• or
• ring B is
• ring A is a benzene ring;
• R1 is a substituent on ring A;
• R2 is a substituent on ring B;
• R3 and R4 are substituents on six-membered ring;
• R1 and R2 are each independently hydrogen, halogen, nitro, cyano, C1-6 alkyl, C1-6 alkoxy, halogenated C1-6 alkyl, halogenated C1-6 alkoxy, C3-6 cycloalkyl, C1-6 alkylamino;
• R3 and R4 are each independently C1-6 alkyl;
• Y is CH;
• Z is (CH2)n, n is 1;
• R5 is C1-6 alkyl;
• the disorder or condition is selected from the group consisting of seizure symptoms;
• inflammatory pain, and
• amyotrophic lateral sclerosis.