NonSelective

Nonselective is an adjective used in science to describe a substance, process, or action that does not distinguish between targets, substrates, or conditions. In practice, nonselective effects touch multiple systems or components rather than isolating a single outcome. The term is often used descriptively; it does not by itself imply superiority or inferiority, but it carries practical implications for efficacy and safety.

In pharmacology and medicine, nonselective drugs or interventions interact with several receptors, enzymes, or pathways. Examples include propranolol, which blocks multiple beta-adrenergic receptors, or atropine, a nonselective muscarinic antagonist. Nonselectivity can broaden therapeutic effects, but it also increases the risk of adverse effects due to off-target interactions. In some contexts, nonselective approaches are desirable when multiple pathways contribute to a disease, while in others, high selectivity is preferred to minimize toxicity.

In chemistry and biochemistry, nonselective reagents or catalysts react with several functional groups or substrates, or lack preference for a single metal ion, leading to mixtures of products. Nonselectivity can be useful in exploratory synthesis or in environmental cleanup, but it reduces yield control and complicates purification.

In research and drug development, selectivity is often quantified by a selectivity index or by comparing activity across targets. A high degree of selectivity is typically sought to reduce side effects, whereas nonselective agents may require monitoring and dose adjustments. The term is context dependent and is used more as a descriptor than a formal category.