Identification
The CAS number of naloxone is 465-65-6; the anhydrous hydrochloride salt has CAS 357-08-4 and the hydrochloride salt with 2 molecules of water, hydrochloride dihydrate, has CAS 51481-60-8

Routes of administration
Intravenous
In hospital settings, naloxone is commonly injected intravenously, with an onset of 1–2 minutes and a duration of up to 45 minutes. While the onset is achieved fastest through IV than through other routes of administration, it may be difficult to obtain venous access in patients who use IV drugs chronically. This may be an issue under emergency conditions. Intramuscular or subcutaneous
Naloxone can also be administered via intramuscular or subcutaneous injection. The onset of naloxone provided through this route is 2 to 5 minutes with a duration of around 30-120min. Naloxone administered intramuscularly are provided through pre-filled syringes, vials, and auto-injector. Evzio is the only auto-injector on the market and can be used both intramuscularly and subcutaneously. It is pocket-sized and can be used in non-medical settings such as in the home. It is designed for use by laypersons, including family members and caregivers of opioid users at-risk for an opioid emergency, such as an overdose. According to the FDAs National Drug Code Directory, a generic version of the auto-injector began to be marketed at the end of 2019. Intranasal
Administration of naloxone intranasally is recommended for people who are unconscious or unresponsive.
This approach to dealing with substance use disorder is to treat it as a medical problem and focusing efforts on reducing the harm produced directly (e.g., overdose) and indirectly (exposure to infectious disease). Clonidine overdose
Naloxone can also be used as an antidote in overdose of clonidine, a medication that lowers blood pressure. Clonidine overdoses are of special relevance for children, in whom even small doses can cause significant harm. However, there is controversy regarding naloxones efficacy in treating the symptoms of clonidine overdose, namely slow heart rate, low blood pressure, and confusion/somnolence. Case reports that used doses of 0.1 mg/kg (maximum of 2 mg/dose) repeated every 1–2 minutes (10 mg total dose) have shown inconsistent benefit. As the doses used throughout the literature vary, it is difficult to form a conclusion regarding the benefit of naloxone in this setting. The mechanism for naloxones proposed benefit in clonidine overdose is unclear, but it has been suggested that endogenous opioid receptors mediate the sympathetic nervous system in the brain and elsewhere in the body. Some poison control centers recommend naloxone in the setting of clonidine overdose, including intravenous bolus doses of up to 10 mg naloxone. Preventing recreational opioid use
Naloxone is poorly absorbed when taken by mouth, so it is commonly combined with a number of oral opioid preparations, including buprenorphine and pentazocine, so that when taken by mouth, only the opioid has an effect. However, if the opioid and naloxone combination is injected, the naloxone blocks the effect of the opioid.