麻醉品 (mázuìpǐn): narcotic; narcotic drug

麻醉品 covers narcotics in the legal/medical sense (opium, morphine etc.) and extends figuratively to anything that dulls the mind — Marx's famous "宗教是人民的麻醉品" (religion is the opiate of the masses) uses exactly this word. For surgical anesthesia, use 麻醉剂 mázuìjì.

memory

麻 (numb) + 醉 (drunk) + 品 (item / product): 'a numbing-drunk product.' The 麻 here is the same 麻 as in 麻木 (numb) and 麻烦 (trouble — from the tangled feeling of cannabis fibers).