Which of the following is NOT a method of internal drug administration?

Intraluminal administration refers to delivering drugs directly into a lumen, such as within a body cavity or organ, which is not typically classified as a method of internal drug administration in the way the other options are. Internal drug administration generally involves routes that allow medication to enter the bloodstream or affect the system internally through more common pathways such as sublingual, rectal, and intranasal methods.

Sublingual administration entails placing a drug under the tongue, where it rapidly dissolves and absorbs directly into the bloodstream through the mucosal membranes. This bypasses the digestive system, providing quick therapeutic effects.

Rectal administration involves introducing medication into the rectum, where it can also be absorbed into the bloodstream. This method is particularly useful for patients who are vomiting or unable to take oral medications.

Intranasal administration delivers drugs through the nasal passages, allowing for swift absorption into the systemic circulation through the nasal mucosa. This method can provide rapid onset of action and is often used for medications that need to act quickly.

In contrast, intraluminal methods are less common and do not fit the standard framework of internal drug administration typically used in clinical practice, making it the correct answer for this question.