This disclosure provides a technology for managing the sensation of pain in a subject in need thereof. Treatment methods according to this invention include administering to the subject a formulation that contains an effective amount of (4-[(4S,5R)-4,5-bis(4-chlorophenyl)-4,5-dihydro-2-[4-methoxy-2-(1-methylethoxy)phenyl]-1H-imidazol-1-yl]carbonyl]-2-piperazinone).