To which part of the body is a topical drug generally applied?

Topical drugs are specifically designed to be applied to the skin or mucous membranes. This method allows the medication to act directly on a localized area, providing targeted treatment for conditions affecting the skin or the surfaces within the body, such as in the mouth or nasal passages. By administering drugs this way, the systemic absorption is minimized compared to other routes, which is often beneficial in reducing side effects.

The choice of skin or mucous membranes for topical application is advantageous for treating local issues while avoiding the complexities associated with other administration routes such as injection or ingestion. For instance, medications used for skin infections, rashes, or localized inflammation often rely on this approach for effective relief.

This targeted administration strategy emphasizes why the other locations mentioned, such as muscles, bloodstream, or digestive tract, are not suitable for topical medications. Muscles involve intramuscular injections, the bloodstream pertains to intravenous administration, and the digestive tract is where oral medications operate through absorption after ingestion. Each of these methods serves different therapeutic needs and mechanisms, but they do not align with the localized application characteristic of topical drugs.