What is the primary method of medication delivery in instillation?

Instillation primarily refers to the administration of medication in the form of drops or ointments. This method is commonly used for delivering medications directly to specific sites such as the eyes, ears, or nasal passages. In these cases, precise applications of liquid medication can target localized areas for absorption and therapeutic effects.

For instance, eye drops are instilled directly into the conjunctival sac, allowing the medication to have an immediate effect on the ocular tissues. Similarly, ear drops can treat ear infections or wax buildup effectively through this direct approach. The choice of drops or ointments allows for controlled dosing and minimizes systemic absorption, which is particularly important in sensitive regions like the eyes and ears.

Other methods of medication delivery mentioned, such as injection, pills, and inhalation, serve different purposes and variables in medication administration. Thus, they do not fall under the definition of instillation, reinforcing why drops or ointment is the correct answer.