How does insuffalating medicine work?

January 25, 2007 1:59 AM

How does the medicine actually get into the blood stream through the nose and sinus lining and are some medicines less effective when insuffalated?
posted by isopropyl to health & fitness (4 comments total)

Until Mr Wilder comes along later, (he did a study on pain relief post-op delivered this way) I will just say this area is incredibly rich in blood vessels and nerves, so once the medicine has traversed the very thin mucosal lining, it's bang into the bloodstream.
Short of IV access it's one of the most direct ways of administering some drugs. BUT they have to be designed for this mechanism of delivery, and generally the problem is not the delivery mechanism but patient compliance. Many people simply do not like snorting drugs this way and in some cases report stinging or other problems.
Long term there may be problems with the sense of smell, which is actully very important in taste.
As to how, their molecules are simply small enough to traverse the mucosa.
I can't right now think of any medicine that that works better given nasally, but I'll wait for himself to get home and report back.
posted by Wilder at 2:44 AM on January 25, 2007

sorry, just to clarify, by "some people" I was referring to people using drugs in a therapeutic sense as opposed to recreational use.
posted by Wilder at 2:46 AM on January 25, 2007

This is actually a hot topic in a number of areas of medicine. Intranasal drug delivery works much the same way as ingesting a drug orally in that the nasal mucosa (and oral mucosa as well) has a large number of blood vessels with just a thin, moist membrane separating them from the outside world. Water-soluble drugs in particular can pass through the mucosa and be quickly taken up by the underlying capillary blood vessels. For drugs that are not water soluble or are very large molecules such as insulin the process is less efficient, but can still be accomplished by tweaking the pH, the delivery solution, or other factors. There are some big advantages to intranasal delivery. First of all, it is fast. In anesthesia we sometimes use it for preoperative sedation with midazolam or nausea control with ondansetron in part because the drugs act quickly when given this way. Another big advantage is that drugs that break down in the GI tract (such as the aforementioned insulin) can be given this way. Yet another advantage is that many drugs that are absorbed in the GI tract are partially metabolized by the liver before reaching the rest of the body (first pass metabolism). This effect does not occur with intranasal medications. In effect, many medicines work faster and better when given intranasally.

So why not give everything via the nose? First of all, it can be uncomfortable. Anything that differs significantly in pH or osmolarity from the normal conditions in the nose will sting. Also, the speed of onset is often less important than the duration of action for drugs that you want to last a while, like antibiotics or antihypertensive medicines. Finally, there are some drugs that have active metabolites (generally formed in the liver) that are responsible for all or part of the drug's effect. These drugs will obviously have less of an effect than if they were given orally.

This is a big topic that I have simplified a great deal to fit into even this long post. A more detailed overview of the topic can be found in this review in the Journal of Emergency Nursing from April, 2004.
posted by TedW at 6:14 AM on January 25, 2007

There is now nasal spray insulin for diabetics, and also sumatriptan for migraine sufferers. Drugs taken this way need to be small lipid-soluble molecules. As thousands of cocaine abusers have found, snorting powder (as opposed to an aqueous solution of the drug) also works. The obvious problem is getting the dose right. A related body cavity which also can absorb drugs directly into the bloodstream while avoiding liver metabolism is the mouth - hence sumatriptan wafers, prochlorperazine and buprenorphine sublingual tablets, and fentanyl lozenges. Undoubtedly we will see more drugs manufactured for these administration routes in the future.
KR (Mr. wilder)
posted by kairab at 11:06 AM on January 25, 2007