A small trial tested how fast Narcan nasal spray reverses breathing depression caused by opioids. The study included 12 people who had never used opioids and 18 people who used opioids daily. All participants received continuous infusions of fentanyl or sufentanil to depress breathing, then were given 4 mg of intranasal naloxone (Narcan).
Narcan restored normal breathing within 2 to 4 minutes in all participants. However, for some, the reversal of elevated carbon dioxide levels took 11 to 17 minutes. During exposure to sufentanil, a high-affinity opioid, recovery was incomplete in some cases: 8 opioid-naive individuals and 10 daily users showed recovery, but others did not.
Seven of the 18 daily opioid users experienced withdrawal symptoms and only participated once. The study used continuous opioid infusions, which do not mimic real-world overdose scenarios where opioids are taken in a single dose.
These findings suggest Narcan works quickly but may not fully reverse breathing depression, especially with potent opioids like sufentanil. More research is needed to understand how naloxone performs in real-world overdose situations.
