nonsystemic

Non-systemic, or nonsystemic, describes substances or treatments whose effects are localized to the site of application and do not rely on distribution through the bloodstream to produce therapeutic results. In pharmacology, a non-systemic agent typically exhibits minimal systemic absorption and limited tissue distribution, in contrast to systemic therapies that reach distant sites via the circulatory system. The term is often used to distinguish local or topical therapies from drugs intended to treat conditions throughout the body.

Common examples include topical or dermatologic preparations such as creams, ointments, gels, and patches that act on the skin and, in some cases, underlying tissues, but are designed to minimize systemic exposure. Ophthalmic solutions, nasal sprays, and inhaled medications used for local effect on the eye or nasal mucosa may also be considered nonsystemic when systemic absorption is low. Local dental anesthetics and mouthwashes are other examples. Nonsystemic formulations are often preferred when the goal is to minimize systemic side effects or drug interactions, or when the disease is confined to a specific organ or tissue.

Important considerations include potential variability in absorption due to skin integrity, mucosal condition, age, or concomitant products; the possibility of local irritation or sensitization; and the fact that even nonsystemic agents can achieve systemic exposure if used at high doses or over large surface areas.

Limitations include that nonsystemic therapies may be less effective for conditions requiring systemic treatment or those involving distant organs. The term is also used in agriculture and other fields to describe substances that act locally without systemic distribution.