Which of the following is NOT a route of medication administration?

Inhalation is indeed a recognized route of medication administration, but it is typically categorized as "inhalation" or "pulmonary" rather than "ingestion by inhalation." Inhalation refers to the process of taking substances directly into the respiratory system, usually through the mouth or nose, where the medication can then act on the lungs or is absorbed into the bloodstream.

Ingestion, on the other hand, refers to the intake of substances through the digestive system, usually through the mouth and swallowed to be processed in the stomach and intestines. Therefore, the phrase "ingestion by inhalation" is contradictory, as it combines two distinct routes that should not be conflated. While medications can be administered through various routes, this phrasing creates confusion, making it clear that this is not an accepted method of medication administration.

The other routes listed—intravenous, rectal, and subcutaneous—are all valid and well-established methods for delivering medications in clinical practice.