One thing to remember about Narcan is that it can wear off faster than a long-acting or extended-release narcotic, and the abuser will renarcotize and go back into respiratory failure again. For one example, an extended release morphine, or even just a big dose of IV morphine can do that.
Repeated doses may become necessary more often than not from street to ER I would imagine.
They taught us that Narcan will last somewhere around 30 min., then the victim will go back under the influence of the drugs.
