We carry a Naloxone kit with us whenever we're out and about in the city, because you just never know when it'll be needed. The kits are free here, available at any pharmacy. This video is a good guide for suspected Opiod overdose, including how to administer the 2 different types of Naloxone.
vimeo.com
SAVE ME Steps: How to Respond to an Opioid Poisoning
The video provide an overview of how to recognize and respond to an opioid poisoning (overdose) using the SAVE ME Steps using either Intramuscular (injectable) or Intranasal (nasal) naloxone.