When you sniff drugs, how do they enter the bloodstream, exactly? Is it via the lungs, the mucosa of the sinuses, a combination…? Can any drug enter the bloodstream via inhalation, or only certain types? And if it is via the mucosa, rather than the lungs, can the drug be absorbed through the anus or vagina? (I assume the mouth is different, the saliva and all.) I’ve heard of people taking wine enemas to get high, which suggests that the mucosa is the key.
It absorbs through the mucosa into the bloodstream. And yes, you can absorb drugs through the vagina or anus, or even the mouth; there are “sublingual” forms of some vitamins that you put under your tongue and which enter the bloodstream from there.
I believe it goes directly to the bloodstream from the vessels in your nose. And yes, the anus can be used to absorb certain drugs as well (as it is possible- though highly inadvisable- to give yourself an alcohol enema and more rapidly start feeling the effects of the drugs in your system. Anything taken orally, meant to be absorbed by the gut, usually has to go through the stomach and undergo digestion, as well as absorption through the gut and then enters the bloodstream.
By bypassing your stomach, you can absorb certain drugs quicker- hence sub-lingual medications (so for the mouth, the quicker route is certain drugs which are pressed under the tongue), anal suppositories, and inhalant, all which can rapidly have access to your bloodstream w/o having to undergo digestion or absorption via your intestines.
Also, yes the makeup of the substance determines how easily it is absorbed and by what route, for example, highly lipophillic or nonpolar molecules and substances are more easily able to pass through phospholipid bilayers than polar ones can- thusly they’re more easily able to be absorbed simply by touch or absorption without requiring as much breakdown of products.
This is why some pesticides can cause organophosphate toxicity without entering a cut or wound, but simply by spraying it onto your skin itself. The substance is easily able to pass through the skin itself and enter the tissue layers and begin working causing spastic paralysis and such.
So yes, it depends on the route, and it depends on the method of absorption, and also the makeup of the substance to help determine its bioavailability.
Some portion of snorted drugs avoid bothering with the bloodstream, and go right to the cribriform plate, where the olfactory nerve has its receptors. This gives the drug direct access to the brain itself, without all that tedious mucking about trying to get through the blood/brain barrier.
Which is why snorting certain drugs is such a powerful rush, and so highly addictive.