A drugA name for a wide variety of chemical substances capable of altering the function of your mind and body in significant ways. These can include over the counter prescriptions, alcohol, and controlled substances. Most drugs are either physically and/or psychologically habit-forming. useful for blocking the effects of opioids. It is therefore utilized to prevent decreased breathing in an overdose situation. Also, when used in conjunction with dangerous opioids, it can limit the risk of dangerous misuse.