Which of the following is NOT a common route of drug administration?

The correct answer is that intranasal is not considered a common route of drug administration compared to the other options listed. While intranasal administration does exist and is utilized for specific medications (such as certain vaccines and treatments for migraines), it is not as widely used or recognized in standard practice as the more traditional routes.

Intravenous administration involves drug delivery directly into the bloodstream, providing rapid onset of action. Subcutaneous administration allows for medication to be injected into the tissue layer between the skin and muscle, often used for vaccines and insulin. Rectal administration involves delivering medications via the rectum, which is commonly used for patients who are vomiting or unable to take medications orally.

Due to their established and frequent use in clinical practice, intravenous, subcutaneous, and rectal routes are more commonly recognized as standard routes of drug administration. Thus, intranasal, while valid, does not fit in the same category of common routes typically encountered in healthcare settings.