<Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (July 2008) (Learn how and when to remove this template message) </Td> </Tr> <P> Sublingual (abbreviated SL), from the Latin for "under the tongue", refers to the pharmacological route of administration by which substances diffuse into the blood through tissues under the tongue . Many drugs are designed for sublingual administration, including cardiovascular drugs, steroids, barbiturates, benzodiazepines, opioid analgesics, enzymes and, increasingly, vitamins and minerals . </P> <P> When a chemical comes in contact with the mucous membrane beneath the tongue, it is absorbed . 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 . </P> <P> 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, by either stomach acid or bile, or by enzymes 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, the oral route is unsuitable for certain substances, such as salvinorin A . </P>

What makes it possible for some medications to be absorbed under the tongue
find me the text answering this question