Which of the following is NOT a route of administration?

The correct choice identifies a route of administration that is not conventionally recognized. The buccal route involves placing medication between the gums and the inside of the cheek for absorption through the oral mucosa. The subcutaneous route refers to the injection of medication into the layer of fat under the skin. The intradermal route involves injecting medication into the dermis, just beneath the epidermis.

While the intranasal route is indeed a recognized method for delivering medication, it allows for absorption through the nasal mucosa, which means it's valid as an administration route. In contrast, the answer indicating that the intranasal route is not a recognized administration route is incorrect, and, therefore, it highlights the importance of understanding various routes of administration in pharmacy practice.

In summary, all the routes mentioned, including intranasal, are valid; the confusion may arise from potentially interpreting 'not a route of administration' incorrectly. Recognizing each method's role is crucial for effective patient care and medication delivery.