Abstract: The present invention provides a salt of demethyl tramadol, i.e., a compound represented by formula (I) or a solvate thereof, a pharmaceutical composition comprising the compound represented by formula (I) or the solvate thereof, and a use of the compound represented by formula (I) or the solvate thereof or the pharmaceutical composition in the treatment of moderate to severe pain. The compound or pharmaceutical composition of the present invention can stably release a drug having analgesic activity in a body for a long period of time, can be conveniently used by doctors and patients while exerting pharmacological effects, and has good medication compliance.

Abstract: Provided in the present invention are a 3-hydroxyl-5-pregnane-20-one derivative as shown in formula I or a pharmaceutically acceptable salt thereof, and a pharmaceutical composition comprising the derivative or the pharmaceutically acceptable salt thereof. The derivative or the pharmaceutically acceptable salt thereof or the pharmaceutical composition comprising the above-mentioned derivative or salt of the present invention can be used to prepare a drug for treating a disease caused by abnormalities in the central nervous system.