Internal EO use and First Pass

A question about internal use was asked. It provides for an excellent review of the subject. The question was about another big company now selling their oils in capsules for ingestion use. My answer to that was to study about the First Pass or First Liver By Pass concept. So to make it easier I went to a simple place and did a simple cut and paste. This is why in pretty much most of the places that teach about the responsible use of essential oils don’t suggest the wide spread use of EO’s. Yes, they can be used internally. But really it is best to use them only when the internal route is indicated for because of some specific medical type condition. The 2nd. to the last paragraph lists better alternative uses. Yes, this whole thing applies to essential oils, the very same as it does to drugs. If we were smart, we would do like these places do, we would do the same thing because it sells a boat load of oils. You will note that it says.. well just read it yourself. Keep in mind that the essential oils act and react in the body system much like drugs do. So much so that the same information, such as this, applies completely.
So here is the cut and paste:

The first pass effect (also known as first-pass metabolism or presystemic metabolism) is a phenomenon of drug metabolism whereby the concentration of a drug is greatly reduced before it reaches the systemic circulation.It is the fraction of drug lost during the process of absorption which is generally related to the liver and gut wall. Notable drugs that experience a significant first-pass effect are imipramine, morphine, propranolol, buprenorphine, diazepam, midazolam, pethidine, cimetidine, lidocaine, and nitroglycerin.

After a drug is swallowed, it is absorbed by the digestive system and enters the hepatic portal system. It is carried through the portal vein into the liver before it reaches the rest of the body. The liver metabolizes many drugs, sometimes to such an extent that only a small amount of active drug emerges from the liver to the rest of the circulatory system. This first pass through the liver thus greatly reduces the bioavailability of the drug.

The four primary systems that affect the first pass effect of a drug are the enzymes of the gastrointestinal lumen, gut wall enzymes, bacterial enzymes, and hepatic enzymes.

In drug design, drug candidates may have good druglikeness but fail on first-pass metabolism because it is biochemically selective.

Alternative routes of administration like suppository, intravenous, intramuscular, inhalational aerosol, transdermal and sublingual avoid the first-pass effect because they allow drugs to be absorbed directly into the systemic circulation.

Drugs with high first pass effect have a considerably higher oral dose than sublingual or parenteral dose. There is marked individual variation in the oral dose due to differences in the extent of first pass metabolism. Oral bioavailability is apparently increased in patients with severe liver diseases like Cirrhosis. It is also increased if another drug competing with it in first pass metabolism is given concurrently. Eg. propranolol and chlorpromazine.

Sourced from Wikipedia.