Structural Biochemistry/Sublingual

Sublingual medications are administered by inserting them directly under the tongue. The medications dissolve rapidly and are absorbed through the mucous membranes of the mouth, where they enter into the bloodstream. The medications are compounded in the form of small, quick-dissolving tablets, sprays, lozenges, or liquid suspensions. The most common sublingual medication is the nitroglycerin tablet, which is a form of pain reliever that is absorbed the fastest when administered sublingually to the body. The sublingual administration method is not always appropriate. Sublingual medications should not be administered if the gums or mucous membranes have open sores or areas of irritation. The patient should not eat, drink, chew, or swallow until the medication has been absorbed. Swallowing the medication must be prevented, since it will decrease the drug's effectiveness as it is digested in the digestive system. Sublingual administration method is fat acting and the body will be able to sense its effect within 5-10 minutes after administration.

Reference
http://www.enotes.com/sublingual-buccal-medication-administration-reference/sublingual-buccal-medication-administration