In medication administration, what does "p.o." signify?

The abbreviation "p.o." stands for "per os," which is a Latin term meaning "by mouth." This indicates that a medication is to be taken orally, which is one of the most common routes of administration for medications. When a medication is prescribed to be taken p.o., it is expected that the patient will swallow the medication, allowing it to be absorbed through the digestive system. This method is often preferred for its convenience and non-invasiveness.

The other options represent different routes of medication administration. Topical refers to applying medication directly to the skin, intravenous signifies that the medication is delivered directly into the bloodstream through a vein, and subcutaneous involves injecting medication into the layer of fat beneath the skin. Each of these routes has its own specific uses and is not synonymous with oral administration.