Which route of administration requires the drug to be absorbed into the bloodstream from the gastrointestinal tract?

The oral route of administration is characterized by the drug being taken through the mouth and subsequently absorbed into the bloodstream from the gastrointestinal tract. This pathway involves several steps: after ingestion, the drug travels down the esophagus, enters the stomach, and then moves into the small intestine, where absorption primarily occurs.

Once in the small intestine, the drug can dissolve and then permeate the intestinal wall, entering the bloodstream. This method of administration is one of the most common due to its convenience, cost-effectiveness, and the ability to administer medications without the need for sterile techniques.

In contrast, intravenous administration delivers the drug directly into the bloodstream, bypassing the gastrointestinal system entirely. Inhalation introduces substances directly to the lungs, where they are absorbed through the alveoli into the blood. The topical route involves direct application to a localized area of the skin, with absorption limited to that site and typically not involving widespread distribution through the bloodstream.