Sublingual

Principle

The principle behind sublingual administration is fairly simple. When a chemical comes in contact with the mucous membrane, or buccal mucosa, it diffuses into the epithelium beneath the tongue. This region contains a high density of blood vessels, and as a result, via first pass metabolism" in the liver before they are distributed to the rest of the body.

In theory, sublingual routes of administration have certain advantages over simple oral administration. This route is often faster, and entering a drug into one's body sublingually ensures that the substance will only come in contact with the enzymes in saliva prior to entry into the bloodstream. Drugs otherwise orally administered must instead survive the extremely hostile environment of the gastrointestinal tract. This may mean a much greater percentage of the original substance is degraded either by the myriad of salvinorin A, only include the sublingual route (that's not to say there aren't other administration routes, such as smoking). Because of its size and relative fragility, salvinorin A cannot pass the GI tract intact and must instead be absorbed across a mucous membrane.

Substance

Almost any form of substance is appropriate for sublingual administration, so long as in that form the substance can readily enter into solution with the saliva in the mouth. Chemicals prepared as powders, solutions, or even aerosol sprays may all make use of this method. However, a number of factors, such as pH, molecular weight, and lipid solubility (to name just a few) of a substance may determine whether the route is practical or not. Based on these properties, it is entirely possible that a drug, which will readily become a solution with saliva, simply diffuses too slowly (or not at all) in the buccal mucosa to be effective.

Psychoactives

In addition to Salvinorin A, other psychoactives may too be applied sublingually. denatonium in order to discourage abuse.

Allergens

Allergens may also be applied under the tongue, and the FDA is reviewing this method of allergen immunotherapy but it is not yet approved in the US. Roder published recent work showing sublingual immunotherapy with grass pollen is not effective in symptomatic youngsters in primary care.^[1]