Pharm Help: Most Effective Route for Morphine Other Than Oral

[bewitched]

We're supposed to be using our Davis Drug Guides to answer the following:

"Research the routes for morphine. Other than the IV route, what 3 routes of morphine are more reliably absorbed than po and give a rationale for your answer based on the instructor presentation for Unit 3 and reading in your textbook."

I've come up with the answer "Other than the IV route, the 3 most-readily absorbed methods of administering morphine are rectal, intramuscular, and subcutaneous." based on the figures given in Davis for the onset/peak/duration times, but I can't find anything in my book or her lecture to justify why these three are the next most effective aside from oral. I understand that rectal route goes through the first pass effect, so it seems like that would actually not be as fast as intramuscular/subcut., because don't those go more directly into the bloodstream?

We're only in the first week of "real" pharmacology so maybe I'm missing something, I'm not sure!

[Sand_Dollar, BSN]

Our teacher told us that morphine is very effective through inhalation, but I haven't found any specific information on that.

What about intrathecally? My Mosby book says "Intrathecal: Onset rapid, duration up to 24 hr".

I just started my Pharm class too, and it seems like we are going over similar stuff.