Well, I guess it depends on where you are. At the service I'm working at PRN, giving ANY medication is a huge pain in the balls. Any Med, not just narcs. Even zofran.
If you open a message bag for anything, you break the numbered seal which then requires a full replacement bag at the ED.
SO... Before you can swap your med bag, you have to fully complete a PCR, print a copy, drive to the local base hospital, which is usually NOT where you've brought the patient, go to the pharmacy, (or find the night nursing supervisor if it's after hours) sign in your old drug bag, fill out a narc/med use form, waste any leftovers in front of the pharm (or RN if the pharmacy is closed), tape your now empty vial or carpo to the PCR and seal that in the OLD bag, get a new bag, break the pharmacy seal, count the contents, re-seal with a new numbered seal, sign a med bag form and then you're able to go run another call.
Biggest pain ever.
When I asked why we don't refill our bag from the Pyxis, they looked at me like I had two heads. "What? Give a paramedic access to the Pyxis? Never!!!"
Have I given fewer meds than I have in the past? Yep. You betcha.