Naloxone is available in 3 formulations: intramuscular and intravenous injection, intranasal (off-label), and as an autoinjector (Evzio, Kaléo, Inc.). Dr. Fudin gave a comprehensive discussion of the pros and cons of each available route of administration. 

Intranasal formulation

Although not yet approved by the US Food and Drug Administration (FDA), intranasal naloxone offers the advantages of being inexpensive and easily accessible, without risk for needle-stick exposure.

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“Intranasal naloxone is used ubiquitously. It is far less expensive compared with the FDA-approved auto-injector formulation,” Dr. Fudin explained.

In a 2009 study by Kerr et al in Addiction, intranasal naloxone was as effective as the intramuscular formulation in reversing heroin overdose within 10 minutes of administration (72.3% vs 77.5%).4 Despite this positive finding, more comprehensive and rigorous studies are needed regarding naloxone absorption with this route of administration.

“Although there are exciting reports of opiate overdose reversals, we do not know how many failures there were when considering attempts at reversal. It is less likely that this route will achieve comparable maximum blood concentrations within the same timeframe compared with any intramuscular formulation,” Dr. Fudin said. “It therefore may not readily and quickly reverse the more fat-soluble drugs such as fentanyl compared with its effect on heroin. In a situation where time is critical, this concerns me.”

As many substance abusers snort one or more drugs, the vasculature in their nasal mucosa could be compromised, and they may have a higher likelihood of a deviated septum, which could also affect intranasal absorption, he pointed out.

Another disadvantage of the intranasal formulation is that it may not be as easy as other options for caregivers and families because it requires users to manually assemble a syringe, plunger, and atomizer and inject half of the formulation in each nostril. Because these component pieces are not sold together as a kit, assembly requires more work on the part of the pharmacist.

This article originally appeared on MPR