Excipient

An excipient is defined as any substance, other than the active pharmaceutical ingredient (API), that is intentionally included in a drug delivery system to facilitate manufacturing, protect the API, or enhance product performance (NIH) [2, 4]. These substances serve diverse functional roles, including acting as binders, disintegrants, lubricants, and preservatives, which are essential for creating stable and effective dosage forms such as tablets or injections (Wikipedia) [6]. While historically classified as pharmacologically inert, modern research has demonstrated that many excipients possess bioactivity and can influence a drug's pharmacokinetics by modulating transporters or metabolic enzymes (PMC) [10]. Excipients are critical for improving the solubility and bioavailability of poorly water-soluble drugs and can be engineered for targeted or controlled drug release (ScienceDirect) [1, 5]. Despite their biological influence on drug absorption and safety, they are not considered therapeutic targets in the context of drug discovery; rather, they are strategic components of the pharmaceutical formulation intended to optimize the delivery of the primary therapeutic agent (Colorcon) [11]. Biopharmaceutical analysts must consider excipient selection carefully, as interactions between these 'inactive' ingredients and the biological milieu can impact the overall clinical efficacy and safety profile of a medication (MDPI) [7, 8].

Other names

Inactive ingredientPharmaceutical aidAdditiveVehicleCarrier

Not applicable; excipients are auxiliary substances in drug formulations and do not serve as therapeutic targets for other drugs.