why the nose such a fast route into the bloodstream?

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I always thought that the nose was designed not only to smell but to filter out dust and toxins from the air entering our respiratory system. If this is the case then why do drugs put up the nose get absorbed into the blood so fast? Shouldn’t the nose have more defences against foreign toxins from entering the blood?

In: Biology

Drugs that are insufflated (snorted into the nose) come to rest in the mucus membranes of the sinuses, they don’t make it all the way down to the lungs. The sinuses have lots of little blood vessels near the surface, so drugs can be absorbed into the bloodstream a little quicker.

I think it’s a side effect of how mucus membranes are designed for secretion. Like your nose runs when you are sick because your body is trying to expel the pathogens packaged into mucus. So all the blood vessels are there to deliver waste and pathogens to be secreted but the side effect is that it’s also absorptive.