Which of the following is a method for drug administration via the skin?

The method of drug administration via the skin is known as topical administration. This approach involves applying medication directly to the surface of the skin where it can be absorbed into the underlying tissues. Topical medications are commonly used for localized treatment, such as in the case of creams, ointments, gels, and patches, which allow for effective delivery of drugs while minimizing systemic absorption and side effects.

In contrast, the other methods listed serve different routes of administration. Otic refers to medication administered in the ear, inhalation involves delivering medication directly to the lungs via breathing, and rectal refers to medication administered through the rectum. Each of these routes has specific indications and mechanisms that do not involve direct application to the skin. Therefore, the essence of the question focuses on topical administration as the method specifically designed for drug delivery through the skin.