NARCAN® Nasal Spray efficacy for emergency treatment of opioid overdose

Questions

What is the difference in efficacy between NARCAN® Nasal Spray and naloxone administered by intramuscular injection?
What are the considerations regarding ease of use of NARCAN® Nasal Spray?
What is the possible impact of nasal passage blockage on efficacy of NARCAN® Nasal Spray?
What is the role of fentanyl in chest wall rigidity?

Citation

Rapid Response Service. NARCAN® Nasal Spray. Toronto, ON: Ontario HIV Treatment Network; May, 2018.