Naloxone hydrochloride dihydrate. Molecular model of the drug naloxone hydrochloride dihydrate (C19.H21.N.O4?H.Cl?2H2.O). This is one of the two components of the drug sold under the brand name Suboxone (the other being buprenorphine hydrochloride). It is a medication used to block the effects of opioids, especially in overdose. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), nitrogen (blue), oxygen (red) and chlorine (green).