Principle
When a chemical comes in contact with the mucous membrane beneath the tongue, it diffuses through it. Because the connective tissue beneath the epithelium contains a profusion of capillaries, the substance then diffuses into them and enters the venous circulation. In contrast, substances absorbed in the intestines are subject to "first pass metabolism" in the liver before entering the general circulation.
Sublingual administration has certain advantages over oral administration. Being more direct, it is often faster, and it ensures that the substance will risk degradation only by salivary enzymes before entering the bloodstream, whereas orally administered drugs must survive passage through the hostile environment of the gastrointestinal tract, which risks degrading them, either by stomach acid or bile, or by the many enzymes therein, such as monoamine oxidase (MAO). Furthermore, after absorption from the gastrointestinal tract, such drugs must pass to the liver, where they may be extensively altered; this is known as the first pass effect of drug metabolism. Due to the digestive activity of the stomach and intestines and the solubility of the GI tract, the oral route is unsuitable for certain substances, such as salvinorin A .
Read more about this topic: Sublingual Administration
Famous quotes containing the word principle:
“Thou art blind to the danger of marrying a woman who feels and acts out the principle of equal rights.”
—Angelina Grimké (1805–1879)
“From the age of fifteen, dogma has been the fundamental principle of my religion: I know no other religion; I cannot enter into the idea of any other sort of religion; religion, as a mere sentiment, is to me a dream and a mockery.”
—Cardinal John Henry Newman (1801–1890)
“There is no teaching until the pupil is brought into the same state or principle in which you are; a transfusion takes place; he is you, and you are he; then is a teaching; and by no unfriendly chance or bad company can he ever lose the benefit.”
—Ralph Waldo Emerson (1803–1882)