Here's an excerpt from pub med:
"Intramuscular injection is the method of installing medications into the depth of the bulk of specifically selected muscles. The basis of this process is that the bulky muscles have good vascularity, and therefore the injected drug quickly reaches the systemic circulation and thereafter into the specific region of action, bypassing the first-pass metabolism."
https://pubmed.ncbi.nlm.nih.gov/32310581/
and here's a nursing link about the three types of injections:
https://www.diplomatpharmacy.com/empower/library/injectable-medications
If you don't believe any of that, I have a puzzle for you:
Smokers need nicotine. Nicotine goes to the brain. Nicotine patches have been used to help with quitting by delivering nicotine by a patch stuck on your skin.
So, if non-venous injections don't get into your circulation, how does nicotine get from the patch to your brain?
“So, if non-venous injections don’t get into your circulation, how does nicotine get from the patch to your brain?”
It crawls across your skin like millions of microscopic sugar ants. 🤷♂️