Which administration method involves placing a drug under the tongue, ensuring rapid absorption and preventing metabolism by the liver?

The sublingual administration method involves placing a drug under the tongue, which allows for rapid absorption into the bloodstream. This route bypasses the gastrointestinal tract and, importantly, avoids first-pass metabolism in the liver. When a drug is taken orally, it must be processed through the digestive system and the liver before entering systemic circulation, which can reduce its effectiveness due to metabolic breakdown. In contrast, administering a drug sublingually allows it to dissolve and be absorbed directly into the blood vessels located in the oral mucosa. This results in quicker onset of action and often higher bioavailability compared to other routes. Thus, sublingual administration is particularly beneficial for medications requiring rapid effects, such as nitroglycerin for angina.