Improvised nasal naloxone devices (INND) commonly used by first responders and the general public deliver significantly less naloxone than regulator-approved devices, according to a study from the National Institute on Drug Abuse (NIDA).

“We definitely know that between the two nasal delivery systems, the improvised device is not as efficient at delivering naloxone to the bloodstream compared to the FDA-approved nasal Narcan spray,” Dr. Philip A. Krieter from NIDA, in Bethesda, Maryland, told Reuters Health by email.

“Using the improvised device twice, two minutes apart, does not come close to reaching the naloxone blood level that is seen after one spray of nasal Narcan. It is important to note that the improvised device is not approved by the FDA,” he said.

The improvised device, consisting of a prefilled naloxone syringe attached to a mucosal atomization device, has been used since 1994 by patients and first responders. In recent years, the U.S. Food and Drug Administration (FDA) has approved Narcan devices for nasal administration of naloxone as well as an autoinjector for intramuscular injection of naloxone, all of which can be used by nonmedical personnel for administering naloxone.

Dr. Krieter’s team compared the pharmacokinetics of the FDA-approved devices and the INND in their study of 30 healthy volunteers of both sexes, 27 of which completed the study.

The peak plasma concentration (Cmax) was highest after intranasal administration of 4 mg of naloxone using the 4-mg FDA-approved Narcan spray device, similar when 2 mg of naloxone were administered using the autoinjector or the 2-mg FDA-approved Narcan spray device, and lowest when 2 and 4 mg were given by one or two intranasal doses using the INND.

The median time to reach Cmax (Tmax) was 20 minutes for all of the intranasal doses and slightly longer after the intramuscular dose, the researchers report in The Journal of Clinical Pharmacology, online March 12.

The total absorption (area under the concentration-time curve [AUC]) was approximately the same when 2 mg of naloxone were given by the autoinjector and 4 mg of naloxone were administered by the 4-mg Narcan spray device, while AUC values were lowest after 2 or 4 mg of naloxone were delivered by the INND.

The relative bioavailability of the intranasal naloxone compared with the intramuscular device was 54 to 62 percent for the Narcan spray devices versus only 19 to 23 percent using the INND.

Exposure during the critical first five, 10, and 20 minutes was approximately two- to three-fold higher using either Narcan spray device or the autoinjector compared with exposure following use of the INND.