Being a super star intern for only 3 months, I've never used Fentanyl, and rarely Demerol (just had a Pancreatitis though). One of the EM attendings at Maryland told me never to use Demerol...
Since then, I asked tons of anesthesiologists and surgeons and attendings, and the only other advantages to using Vitamin D is that it does give a "supratentorial" effect, which may help the patient believe the pain medicine is working more.
I give a lot of MS though.
WHile we're on the topic, I've given a lot of placebo nicoderm patches. I tell the RN to just put some Tegaderm on it. Its worked 100%. "Thanks so much, doc, you're a live saver!" I only use it for those really annoyuing House Officer calls.
Q, DO