Batch-Specific Potency — Lot-Level Assay Driving GMP Batching

This topic is part of the SG Systems Global regulatory & operations glossary.

Updated November 2025 • Potency Basis, Potency Adjustment Factor, LOD Adjustment, Batch Weighing • Assay, API, GMP, Batching

Batch-specific potency is the measured strength of an active ingredient or concentrated intermediate assigned to a particular lot, usually expressed as % assay on a defined potency basis (as-is, dry or anhydrous). Instead of assuming every lot is 100 % potent, regulated manufacturers attach a numeric potency value to each lot and use that value to calculate how much material to charge into a batch. In practice, batch-specific potency is the bridge between laboratory results and the setpoints used by batch weighing, dosing and filling systems.

“Batch-specific potency is what turns an assay on paper into a weight on the scale. Without it, ‘100 mg’ on the label is just an assumption.”

1) What Is Batch-Specific Potency?

Batch-specific potency is a lot attribute. For each lot of API, premix or other potency-critical component, the laboratory determines an assay (for example, 97.8 % on an anhydrous basis) and assigns that value to the lot. That potency then becomes the reference used whenever the material is charged into a manufacturing batch. In practical terms, the system stores at least:

• the numeric potency value (e.g. 97.8 %);
• the associated potency basis (as-is, dry, anhydrous);
• the analytical method and result identifier (often via an analytical lot link); and
• the effective date, approval status and reviewer signature.

When the batch is created, the formulation knows how much active is required. Batch-specific potency answers the question: “How much of this particular lot do we need to weigh to deliver that active?” In regulated manufacturing, this is expected for APIs, high-potency intermediates and, increasingly, for vitamins, enzymes and other functional ingredients in food, cosmetics and supplements.

2) Relationship to Potency Basis and Assay

Potency cannot be interpreted correctly without understanding the basis on which it is reported. A lot might be 97.8 % potent on anhydrous basis, 95.2 % on dry basis and 92.5 % as-is, depending on moisture and volatile content. The potency basis tells the system which number to use in the batch calculation. Batch-specific potency ties the numeric assay and the basis together so the manufacturing system does not “guess” which figure is correct.

In a well-designed system, the test results from HPLC or other analytical methods are captured in a LIMS and then transferred into the MES or ERP as batch-specific potency. The same basis is used consistently in the potency / assay adjustment logic, in the mass balance and in potency-normalised yields, avoiding interpretation errors during investigation or audit.

3) From Batch-Specific Potency to Potency Adjustment Factor

Once a lot has an assigned potency, the system converts that value into a potency adjustment factor. This is usually a dimensionless number derived from the ratio of target potency to actual potency. For simple cases, the factor might be defined as:

• Factor = 100 / Batch-Specific Potency (%) — for actives where the recipe is written assuming 100 % potency; or
• Factor = Declared Potency / Batch-Specific Potency — where the label claim is not 100 % of the chemical entity.

The factor is then applied to the theoretical quantity calculated in the recipe formulation. The result is an adjusted gross weight that should be charged to the batch. By keeping batch-specific potency and the adjustment factor visible, organizations can show exactly how the calculation was derived and which lot-level data influenced the decision.

4) Interaction with LOD, Moisture and Percent Solids

In many materials, the potency value is not just a single assay number. Moisture or volatiles measured through loss-on-drying (LOD) adjustment, and solids content captured as % solids basis, change how much “real” active is in the lot. Batch-specific potency may therefore be calculated as a composite, for example:

• chemical assay (% of active),
• minus moisture content (% water or volatiles),
• scaled to an anhydrous or solids basis.

For solutions and suspensions, the concentration-adjusted charge builds on batch-specific potency by considering both the concentration of the solution and any solvent content correction. The underlying principle is the same: all tests that affect effective strength must be reflected in the lot-level potency value used by the batch calculation engine.

5) How Batch-Specific Potency Drives Batch Weighing

In a potency-aware batch weighing process, the operator never manually calculates the impact of potency on the target. Instead:

• the batch step identifies the ingredient and calls the formulation setpoint (e.g. 10 kg of API at 100 %);
• the system retrieves the selected lot and its batch-specific potency value;
• the potency adjustment factor is calculated in real time; and
• the target weight presented on the scale is automatically adjusted.

Where gravimetric weighing is integrated directly with MES, the potency-adjusted target is hard-gated: the batch step cannot be completed unless the measured weight falls within the defined tolerances. This creates a clear data-integrity trail showing that the potency-corrected charge was verified and that reweigh, top-up or investigation rules were followed when the tolerance was exceeded.

6) Corrected Active Content and Mass Balance

Because batch-specific potency provides the percentage of active in the lot, it is straightforward to calculate the corrected active content contributed by each addition. For every charge event, the system can store both:

• gross weight of material added; and
• equivalent weight of active based on batch-specific potency.

This dual view supports more accurate mass balance calculations, yield analysis and investigation of OOS results. It also prevents confusion when the same batch size is manufactured with lots of different potency: the amount of powder may change from batch to batch, but the active content can still be reconciled across the process and into the finished units on a consistent basis.

7) Potency-Normalised Yield and Active-Equivalent Consumption

When batch-specific potency is implemented consistently for key ingredients, it becomes possible to move away from purely gross-weight metrics. Potency-normalised yield expresses yield in terms of active content delivered versus active content expected, rather than simply comparing kilogrammes of powder. Similarly, active-equivalent consumption measures material usage in units of active substance when posting to ERP or costing models.

These views can substantially improve understanding of process performance. For example, a campaign that appears to have poor yield on a gross-weight basis may be perfectly acceptable once potency differences between lots are accounted for. Conversely, excessive losses of active content may be hidden behind apparently normal weights if potency is not taken into account. Batch-specific potency is the key enabler for these more sophisticated, and more truthful, metrics.

8) Test-Driven Setpoint Adjustment and Dynamic Recipe Scaling

In some processes, potency is only one of several tests that influence how a batch should be run. Solids, pH, titer or viscosity may require the formulation to be adjusted in a controlled way. Batch-specific potency feeds into broader test-driven setpoint adjustment, where a change in assay or solids content triggers an automatically calculated update to setpoints.

Where the batch purposefully allows for changing batch size or fill volume, the same data can support dynamic recipe scaling. Instead of discarding material that is significantly off target or forcing operators to improvise, the system can—under controlled rules—adjust the number of units, the batch size or the amount of compensating ingredients, while maintaining the intended dose per unit and staying within validated boundaries. Batch-specific potency is one of the core variables that makes this kind of controlled flexibility possible.

9) In-Process Assay Gates and Release Decisions

Batch-specific potency is often first assigned on release of the incoming lot. However, some operations rely on potency determined at an in-process stage—for example, titer in a bioreactor or assay of a concentrated intermediate before dilution. In these situations, the batch step is held behind an in-process assay gate: the process cannot proceed until the test result is in the system, approved and linked to the relevant lot or intermediate.

This creates a strong data-integrity story for regulators. The batch record shows that the potency result was available, reviewed and locked before any potency-dependent calculations were executed. Where hold / release status is used, the release of the in-process material can be tied to verification that the assay result meets specification and that the potency value feeding the downstream weighing or filling logic is correct and complete.

10) Stability-Driven Overage and Specification Windows

In some products, an intentional overage is added to compensate for expected potency loss over shelf life. Stability-driven overage is distinct from batch-specific potency: one reflects the behaviour of the material over time, the other reflects the measured strength of the lot at the time of use. Nevertheless, the two interact closely.

If the product is designed with a 3 % overage and a lot arrives at 99 % potency, the batch-specific potency and the overage policy together determine how much material should be charged. The system must also observe OOS limits and any labelled upper strength limits for the finished product. For this reason, many organizations define both a specification window for batch-specific potency and rules for how stability-driven overage is applied or reduced when potency is unusually high.

11) Data Integrity, Traceability and Analytical Lot Links

From a data-integrity perspective, batch-specific potency is only credible if its origin can be traced back to a specific test, analyst and instrument run. This is where the concept of an analytical lot link becomes important. The link ties the lot’s potency value in MES or ERP to the exact assay result in LIMS or the laboratory test record. Any correction to the result is versioned and re-authorised, and a controlled interface ensures that potency cannot be changed informally at the point of use.

Combined with audit trails and ALCOA+ principles, this structure allows regulators to follow the potency value from sample collection through analysis, result entry, review, approval, system transfer and final use in the batch. The same value that appears in the weighing setpoint can be traced back to its laboratory origin without gaps or unverified transcription steps.

12) Typical Use Cases by Industry

While batch-specific potency is most associated with pharmaceutical APIs, it is increasingly common across regulated and quasi-regulated sectors:

• Pharmaceuticals and biologics: APIs, intermediates, concentrates, enzyme systems, biological titers and neutralising agents.
• Dietary supplements and nutrition: vitamins, minerals, botanicals, probiotics and functional ingredients where label claims must be met throughout shelf life.
• Food and beverage: fortification premixes, enzymes and additives controlling critical quality attributes.
• Cosmetics and personal care: actives subject to concentration limits, efficacy claims or safety margins.
• Chemicals and speciality materials: catalysts, initiators and performance-driving components where activity is concentration-dependent.

In each case, the fundamental pattern is the same: tests determine how strong the lot really is, batch-specific potency records that fact, and execution systems use it to make sure the right amount of active enters the process.

13) Common Pitfalls and Failure Modes

Organizations that partially implement potency logic can run into avoidable problems. Typical issues include:

• Inconsistent basis: using as-is potency in some calculations and dry-basis potency in others, leading to unexplained variability.
• Manual overrides: operators manually editing targets to “match the CoA,” bypassing the controlled calculation derived from batch-specific potency.
• Unlinked data: potency stored in ERP, assay held in LIMS, batch executed in MES, but no robust analytical lot link to tie them together.
• Ignoring intermediates: applying batch-specific potency only at the raw-material stage, not to concentrates or solutions created during processing.
• Missing yield impact: continuing to judge yields on gross weight while potency varies significantly from lot to lot.

Addressing these issues usually involves strengthening master data, enforcing calculation rules in the execution layer and tightening interfaces between laboratory, MES and ERP systems so that potency is treated as a controlled attribute throughout the lifecycle of each lot and batch.

14) Integration with Master Data and Recipes

Batch-specific potency does not exist in isolation. It is referenced by master recipes, formulas and bills of materials (BOM). Recipes should explicitly state whether quantities are expressed on a potency-normalised basis and how potency is expected to be handled (for example, “all API charges are potency-adjusted to 100 % on anhydrous basis”). Recipe versioning ensures that any changes in potency policy, test method or calculation approach are properly controlled.

In more advanced setups, potency information is also used when planning lots and scheduling batches. For example, the planner may prefer to group batches that use lots of similar potency to reduce variability in process behaviour, or to prioritise lots that are trending downward in stability-study results. In all these cases, batch-specific potency is the master-data attribute that makes potency visible to planning, not just to operations.

15) Why Regulators Care About Batch-Specific Potency

Regulators expect finished products to meet their label claim and specification throughout shelf life. Where raw-material potency varies, it is not enough to show that an average charge was applied; manufacturers must demonstrate that dose decisions were made using current, verified data and that calculations were performed correctly. Batch-specific potency is the mechanism that connects those expectations to the day-to-day reality of batching and weighing.

A robust implementation allows an inspector to follow the story: from CoA or in-house test, to potency and basis, to potency adjustment factor, to batch targets and actuals, and finally to finished-product assay and stability studies. When that story is coherent, traceable and supported by audit trails, it becomes much easier to defend the control strategy and to show that potency variability was anticipated, quantified and controlled rather than ignored.

FAQ

Q1. How is batch-specific potency different from a standard assay result?
An assay result is a laboratory measurement for a sample. Batch-specific potency is that result converted into a controlled lot attribute, with defined basis and approvals, that is used by batching and weighing systems.

Q2. Do all materials need batch-specific potency?
No. It is typically reserved for APIs, intermediates, premixes and other ingredients where potency materially affects dose or label claim. Low-risk excipients may not require potency management.

Q3. Can batch-specific potency be changed after a lot is released?
It can be corrected, but changes should follow formal change control, with clear linkage to revised laboratory results and impact assessment for any batches already manufactured.

Q4. How does batch-specific potency relate to stability-driven overage?
Batch-specific potency reflects measured strength at the time of use. Stability-driven overage reflects expected change over time. Both factors influence how much active is charged but arise from different parts of the control strategy.

Q5. What is a practical first step to implement batch-specific potency?
Start by defining which materials require potency control, standardise the potency basis for each, and integrate assay results from LIMS into the lot master data so weighing setpoints can be calculated automatically instead of manually.

Related Reading
• Potency & Batching: Potency / Assay Adjustment | Potency Basis | Potency Adjustment Factor
• Test-Driven Batching: LOD Adjustment | % Solids Basis | Concentration-Adjusted Charge | Test-Driven Setpoint Adjustment
• Yield, Mass Balance & Records: Mass Balance | Potency-Normalised Yield | Active-Equivalent Consumption | Electronic Batch Record (eBMR)