Which of the following is NOT an enteral route of administration?

The intravenous route of administration is categorized as a parenteral route, which means it bypasses the gastrointestinal tract entirely. In contrast, enteral routes involve the use of the digestive system for drug absorption. The oral and rectal routes are both enteral because they rely on the gastrointestinal tract for the absorption of medications, whether through the mouth or rectally. Sublingual administration also utilizes the gastrointestinal system, as it involves placing medication under the tongue, allowing for absorption through the oral mucosa. In this context, the intravenous route stands out as the method that does not engage the digestive system, confirming its classification as NOT an enteral route.