Naloxone is the most proximal intervention that we have to reduce premature mortality associated with unintentional opioid overdoses and it has been demonstrated to be highly efficacious, safe and cost-effective. The effectiveness of naloxone formulations may vary depending on the setting and the person responding to the overdose.Naloxone is the most proximal intervention that we have to reduce premature mortality associated with unintentional opioid overdoses. Opioid dependence causes a significant amount of disease burden globally [1], and an Australian study estimated that 86% of deaths among patients receiving opioid substitution therapy were potentially preventable [2]. It is important to contextualize the discussion of unlicensed drug formulations so that we can weigh the risks versus the benefits in response to this timely question raised by Strang and colleagues, as well as keep in mind that it is the formulation and not the drug itself that is the focus of debate.We have a health state that causes significant premature mortality globally and a reversal agent that is not only efficacious, but also has an excellent safety profile [3] and is highly cost-effective [4]. Intranasal (i.n.) naloxone is advantageous because it reduces the risk of needle-stick injuries and allows naloxone administration by emergency medical services (EMS) that are not certified for intramuscular (i.m.) or intravenous (i.v.) medication administration. While it would be ideal if regulations could be modified to allow all EMS to administer parenteral (i.m./i.v.) naloxone, this has proved to be a difficult front on which to make progress. To this point, a recent study in the United States found that only 38% of states allow basic level EMS to administer i.m. naloxone and there are no states that allow basic-level EMS to administer i.v. naloxone [5]. Another advantage of i.n. naloxone is that time to administration may be accomplished more quickly than i.v. administration among injection drug users (IDUs), whose chronic drug use can result in inaccessible, scarred veins [6]. Parenteral naloxone is believed to be superior to i.n. naloxone [7] however, there are important differences in outcomes based on whether the research was conducted in the pre-clinical or pre-hospital setting.A pre-clinical animal study found that i.n. naloxone, when maintained in the nasopharynx, was equivalent to i.v. naloxone in terms of bioavailability and duration of action [8]. A study in healthy volunteers found that i.n. naloxone had a faster onset (time to peak concentration) compared to i.m., but i.n. had poor bioavailability and a shorter duration of action [7]. This study found that i.m. naloxone had 36% bioavailability, reached peak concentration in 12 minutes and maintained measureable concentrations for nearly 4 hours; i.n. naloxone had 4% bioavailability, peak concentration within 6-9 minutes and measurable concentrations for nearly 3 hours [7]. Dowling and colleagues (2008) noted that this study was conducted with conscious healthy volunteers and...