Formulation & Product Design
Designing the thing itself: dosage form or device architecture, materials, components, specifications, and the human factors that decide whether it can be used correctly by the people who will use it. Design fixes most of the risk and most of the cost before manufacturing ever begins. A material chosen for availability, or a device whose use error was never studied, becomes a control burden operations carries for the product’s whole life.
What an explainer is not
A topic explainer is SPEQ’s synthesis of what a practice involves, cited to the standards that govern it. It does not reproduce their text, and it does not determine which of them apply to your product or process.
[ POSITION IN THE FRAMEWORK ]
7 DIMENSIONS · 23 LINKSFormulation decisions are the ones the whole lifecycle inherits: excipient, container and route are chosen early, constrain every later process and stability question, and are the hardest changes to make afterwards.
06 · QUALITY MATURITY — FORMULATION & PRODUCT DESIGN, REACTIVE TO ADAPTIVE
The formulation is what worked first in the laboratory. Its choices were not recorded as choices.
A development report exists, but it records what was done rather than why each alternative was rejected.
Attributes are linked to performance, excipient and container choices are justified against what they must deliver, and stability-indicating behaviour is understood rather than observed.
Manufacturability, supply and patient use are design inputs alongside performance, so the formulation is chosen to be made and used rather than only to work.
The design space of the formulation itself is understood, so a supply disruption or a component change is a bounded assessment rather than a redevelopment.
SPEQ’s shared five-stage progression, labelled synthesis — not the FDA QMM rating scale. Where does your organization sit? Score your quality system →
07 · REGULATORY & EVIDENCE
GOVERNING STANDARDS · 5
Derived from the 5 standards SPEQ maps to this subject, across 3 regulatory bodies: ICH, ISO, IEC.
RECORDS & OBJECTIVE EVIDENCE
- Formulation development records including alternatives considered and rejected
- The link from formulation attributes to the performance they deliver
- Excipient and container selection rationale, including supply considerations
- Compatibility and stability data supporting the chosen composition
- Human-factors or administration considerations where the route requires them
COMMON INSPECTION FINDINGS
- A formulation with no recorded rationale for its principal components
- Excipient grade or supplier treated as interchangeable with no compatibility basis
- Container closure selected late, with compatibility assessed after clinical supply
- Stability behaviour observed but never explained, so a change cannot be assessed
- Administration or use requirements addressed only after the formulation was fixed
Specifications are a design output, not a QC artefact
A specification states what the product must be, and ICH Q6A frames the decision as which tests and acceptance criteria are necessary to assure quality — a judgement grounded in the development data rather than a list assembled from precedent. Specifications set by copying a similar product tend to include tests that measure nothing informative and omit the attribute that actually drives performance.
The failure this produces is specific and expensive: a specification that omits an attribute the process depends on will be met by material or product that does not work, and the supplier or the manufacturing site will be entirely correct in saying it complied. Every such gap is a design decision made by default.
Material selection is a fifteen-year commitment
Materials are chosen during development for performance and availability, and inherited by operations as a supply-chain and compliance obligation. An excipient from a single qualified source, a polymer with a narrow processing window, a component whose supplier will not accept change notification — each is a supply risk created by a technical decision taken years before anyone will feel it.
For devices there is an additional layer: material selection drives biological evaluation under ISO 10993-1, and a late material change can invalidate the biocompatibility assessment entirely. The practical control is to bring supply and regulatory judgement into material selection while alternatives are still open, rather than qualifying the chosen material afterwards.
Human factors decide whether the design survives contact with users
IEC 62366-1 applies usability engineering to medical devices, and its central claim generalises well beyond devices: use error is a design characteristic, not a user characteristic. A device that is used incorrectly by trained clinicians has a design problem, and studying that during development is far cheaper than discovering it through complaint data.
The same reasoning applies to a combination product’s administration steps and to a drug’s packaging and labelling. Where a use-related hazard is identified, the mitigation hierarchy matters: design it out first, protect against it second, and warn about it only when the first two are exhausted. A warning added to a leaflet is the weakest available control, and it is the one most often reached for.
SPEQ interpretation — design freeze is when the cost curve turns
Before design freeze, changing a material, a dimension or an interaction costs a decision. After it, the same change costs requalification, potentially a regulatory variation, and possibly a biocompatibility or stability programme. Everyone knows this and organisations still routinely defer design questions past the point where they were cheap, because the pressure at that stage is to move.
The countermeasure is to name the questions that must be answered before freeze — the ones where being wrong is expensive rather than merely inconvenient — and to treat leaving one open as a decision requiring the same authority as a change would. That converts a drift into a choice, which is usually enough to stop it.
FREQUENTLY ASKED
How should product specifications be set?
From development data, as a judgement about which tests and acceptance criteria are necessary to assure quality — the framing ICH Q6A uses. Specifications assembled by copying a similar product tend to carry tests that measure nothing useful and omit the attribute that actually drives performance, and the omission is only discovered when compliant material does not work.
Why does material selection create long-term risk?
Because it is a technical decision with supply and regulatory consequences that arrive years later: a single qualified source, a narrow processing window, a supplier who will not accept change notification. For devices it also drives biological evaluation under ISO 10993-1, so a late material change can invalidate the biocompatibility assessment.
Is use error a user problem or a design problem?
A design problem. IEC 62366-1 treats use error as a design characteristic, and a device used incorrectly by trained clinicians is telling you something about the design. Studying it during development costs a usability study; discovering it through complaint data costs a field action.
Why is a warning the weakest mitigation?
Because it relies on the user reading, remembering and acting on it under real conditions. The mitigation hierarchy is to design the hazard out first, protect against it second, and inform about it only when the first two are exhausted — and the warning is the option most often reached for precisely because it is the cheapest to add late.