Excipients serve a range of functional roles within a finished dosage form. Depending on the formulation, a single product may contain binders, fillers (diluents), disintegrants, lubricants, preservatives, colourants, sweeteners, or coating agents , each selected for a specific technological purpose rather than any therapeutic effect of their own.
Although excipients are defined by their inactivity at the intended dose, they are not biologically inert in an absolute sense. Route of administration, concentration, and individual patient factors (including allergies and intolerances) can all influence how a given excipient is tolerated. Lactose, certain synthetic dyes, and polyethylene glycols are among the excipients with documented tolerability considerations in specific populations.
In Australia, excipients present in therapeutic goods must be disclosed and assessed as part of the Therapeutic Goods Administration (TGA) registration or listing process under the Therapeutic Goods Act 1989 (Cth). The TGA publishes a permitted excipients framework, and sponsors are required to demonstrate that excipient levels fall within acceptable limits for the intended route of administration and patient population.
Regulatory requirements for excipient safety and quality reference internationally recognised compendia including the International Council for Harmonisation (ICH) guidelines , particularly ICH Q8 (Pharmaceutical Development) , and pharmacopoeial standards such as those of the British Pharmacopoeia (BP) and United States Pharmacopeia (USP), both of which are recognised in Australian regulatory practice.
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