sublingual

Sublingual refers to a location under the tongue and to a route of administration that delivers substances through the mucous membrane of the floor of the mouth. The term comes from Latin sublingualis, meaning “under the tongue.” Sublingual administration is used for drugs and, less commonly, nutrients or hormones, to take advantage of the region’s rich blood supply.

In practice, a small dose is placed under the tongue and allowed to dissolve. The substance diffuses across the oral mucosa and enters the systemic circulation via the deep lingual veins, bypassing the gastrointestinal tract and hepatic first-pass metabolism. This can produce a rapid onset of action and, for certain drugs, improved bioavailability compared with swallowing.

Common formulations include sublingual tablets, films, and sprays. Medications frequently delivered this way include nitroglycerin for angina, buprenorphine for opioid dependence, and various fentanyl products for pain. Sublingual delivery is also used for some vitamins and hormones in specialized products.

Advantages of the sublingual route include rapid onset, avoidance of first-pass metabolism, convenient dosing, and discreet administration. Limitations include the need for patient cooperation, potential mucosal irritation, and limited suitability for large doses or drugs that do not readily permeate the oral mucosa. Efficacy depends on factors such as saliva flow, mucosal integrity, and the properties of the drug; improper use (chewing or swallowing before dissolution) can reduce effectiveness.