Beyond-Use Time

This glossary term is part of the SG Systems Global regulatory & operations guide library.

Updated January 2026 • 21 CFR Part 212 PET drug cGMP, EOS-to-use window governance, decay timing, dose release controls, transport constraints, chain-of-custody, labeling, exceptions, audit-ready records • Primarily PET & radiopharmaceutical operations (cyclotron sites, radiochemistry labs, nuclear pharmacies, hospital PET production)

Beyond-Use Time (often abbreviated as BUT) is the hard stop that defines when a radiopharmaceutical dose or lot is no longer permitted to be used, administered, or released for patient care. In PET drug operations governed by 21 CFR Part 212, BUT is not “a nice label detail.” It is a control boundary that protects identity, strength, quality, and purity in the face of short half-life products, rapid release decisions, and real-world transport and workflow delays.

The business value is blunt: BUT discipline prevents wasted runs, prevents unsafe or ineffective administration windows, and reduces the number of “heroic saves” that create errors. The compliance value is equally blunt: if you can’t prove how you calculated the use window, how it was applied at the point of action, and how overrides were prevented, you don’t have time control—you have hope.

Tell it like it is: the BUT failure pattern is predictable. Teams treat BUT like an informational timestamp, then operational reality takes over. A dose is prepared early “to help dispatch,” a courier is delayed, a unit sits in a fridge, and a tech tries to use it anyway because the patient is ready. If your system allows that sequence without an enforced stop, it will eventually happen. A controlled BUT program ties the time window to the specific item (dose/lot), anchors the reference time (often End-of-Synthesis Time or calibration time), records the basis for decay math, and blocks release, picking, and administration beyond the permitted window.

“Beyond-use time isn’t a label. It’s an operational gate that decides whether a dose can legally and safely move forward.”

1) What beyond-use time is (and what it is not)

Beyond-use time is a controlled eligibility boundary. It answers a single operational question with zero ambiguity: can this dose still be used? If “yes,” the dose can proceed through permitted actions (release, picking, handoff, administration). If “no,” it must be blocked, quarantined for disposition, and handled under controlled rules.

It is not a “best by” suggestion. It is not an optional label field. And it is not a decision left to whoever is under the most schedule pressure. In PET operations, time is a quality constraint. The only safe stance is to treat BUT as a gate that the system enforces, not a timestamp that people interpret.

2) Why BUT exists in PET operations

Radiopharmaceuticals are time-dependent by nature. Activity decays continuously, and practical usability depends on your process, your validated controls, and your clinical delivery model. BUT exists because the combination of:

• rapid decay (activity drops quickly),
• fast release cycles (decisions happen under time pressure),
• transport reality (couriers, traffic, loading docks, handoffs),
• patient scheduling (appointments shift, scanners run late),
• control expectations (prove you didn’t “make it work” beyond your defined window)

creates a predictable risk: if you don’t enforce time, people will bend time. BUT is how you prevent bending. When enforced properly, it protects patients, protects the facility, and protects the credibility of your record set.

3) BUT vs expiry time vs shelf life (stop mixing the words)

These terms get mixed constantly, and that confusion creates compliance drift. Use them with discipline:

• Shelf life / expiry dating typically refers to stability over a defined period under defined storage conditions.
• Expiry time is often used for a specific timestamp after which the item is no longer acceptable.
• Beyond-use time is the operational boundary tied to the unit-of-use and the workflow reality of short-lived products.

Tell it like it is: in PET operations, the label “expiry” can be interpreted as purely chemical stability, while BUT is the actionable safety boundary that drives workflow gating. If your teams use the words interchangeably, your program will become inconsistent. Pick the term that matches your operating model and enforce it the same way everywhere.

4) Reference time anchors: EOS, calibration time, and event timing

Every BUT rule must declare its anchor. Without an anchor, you don’t have time control—you have disagreements. Common anchors include:

• End-of-synthesis time (EOS): a manufacturing anchor that ties to the production record.
• Calibration time: a dose-centric anchor used in patient delivery and activity statements.
• Container close time: used when the unit-of-use is defined at closure.
• Release time: used in some operating models, but risky unless defined tightly.

In many PET workflows, EOS is the cleanest anchor because it is a single, auditable event tied to the manufacturing record. Calibration time is often essential for dose labels. The key is not which anchor you choose, but that you choose one, document it, and use it consistently across labeling, release logic, and handoffs.

5) Decay and activity basis: making the math defensible

Time control in radiopharma is inseparable from activity control. If you calculate BUT using decay math (explicitly or implicitly), you must document your basis:

• isotope identity (don’t assume),
• reference activity at a defined time (EOS or calibration),
• calculation method (system-calculated vs manual),
• instrument credibility (dose calibrator checks where applicable),
• acceptance boundary (what defines “still usable” in your operating model).

Tell it like it is: undocumented decay math is an audit gift. If you can’t show how the time window was determined, you can’t defend why a late dose was blocked or why an early dose was allowed. A robust approach is to make the system perform the calculation, store the inputs, and keep the operator out of the math business. Operators should execute, not improvise equations.

6) Defining the BUT rule: product-specific and process-specific

A usable BUT rule has three parts:

• Definition: “Beyond-use time is the latest allowable time for X action.”
• Scope: “Applies to doses prepared under Y process and Z distribution model.”
• Enforcement: “Blocked by system at release, pick, ship, and administration steps.”

In practice, BUT can differ based on product, formulation, validated stability, sterile filtration approach, and delivery distance. Don’t pretend there’s one universal number. Define BUT per product class and per workflow type, then apply the correct rule by linking the dose to the product master and the process route. If your BUT rule is a sticky note, it will become a negotiation during busy days.

7) Labeling and presentation: making BUT unmissable

Even with perfect system enforcement, humans still need clarity. Labels and screens should make BUT obvious:

• Large, unambiguous time format (no tiny print, no confusing abbreviations),
• Time zone discipline where multi-site or cross-region distribution exists,
• Anchors shown (e.g., “Cal Time” vs “EOS”),
• Status cue (eligible / expiring soon / expired),
• Scan-first confirmations so the right dose is the one being evaluated.

The most common operational mistake is not “wrong math.” It’s “wrong item.” A dose label that makes BUT obvious but doesn’t enforce identity capture still allows wrong-dose use. Design labeling and UI together: identity first, then time eligibility.

8) Unit-of-use control: lots, doses, syringes, and vials

BUT must be applied to the correct unit of use. That means your system must know what it’s controlling:

• Lot-level BUT when the whole lot shares a single usable window.
• Dose-level BUT when doses have individual calibration times or preparation times.
• Container-level BUT when a vial/syringe has a specific identity and timing.
• Split/partial logic when one lot generates multiple units with different handling realities.

Tell it like it is: if you control BUT at the lot level but operate at the dose level, people will “borrow” assumptions and it will drift. The control must match the real workflow. In most PET distribution models, dose-level control is the practical requirement because handoffs and patient scheduling happen at dose granularity.

9) Handoffs and transport: chain-of-custody time pressure

BUT doesn’t live in the lab; it lives in the handoff chain. Every step consumes time margin. Your operating model must account for:

• pick/pack time and staging delays,
• courier dispatch timing and route variability,
• handoff confirmation (who received it and when),
• arrival verification at the destination,
• patient readiness at the final moment of use.

Time control without chain-of-custody control is weak. You need proof not only that the dose was “within time” at the facility, but that the dose remained eligible through the handoff. That’s why BUT should be evaluated at multiple points: release, pick, dispatch, and (when feasible) receipt or use confirmation.

10) Hard gates: how you prevent use beyond BUT

A hard gate is the difference between a compliant program and an aspirational one. Hard gates include:

• release gate: cannot be released beyond BUT, even if “we need it,”
• pick gate: cannot be picked for shipment beyond BUT,
• ship/dispatch gate: cannot be confirmed for dispatch beyond BUT,
• receipt gate: flagged at receipt if BUT margin is insufficient,
• use gate: if the facility controls administration workflows, block beyond BUT.

Tell it like it is: “soft warnings” are not controls under pressure. People click through warnings when patients are waiting. If your program depends on warnings, your program will fail eventually. Use warnings for “expiring soon” and hard stops for “expired.”

11) Holds and conditional release: BUT is still enforced

Conditional release models (e.g., sterility release pending) create a tempting failure mode: “we’ll release it because we’re already late.” The correct posture is the opposite: conditional release does not override time boundaries. If time is exceeded, disposition is controlled, not negotiated.

Operationally, this means your system must evaluate BOTH conditions:

• quality eligibility (release status, holds, pending results), and
• time eligibility (within BUT window).

If either fails, the item is blocked. That’s how you avoid creating a “time override culture” that quietly becomes standard practice.

12) Exceptions: what happens when time windows are missed

Missed time windows are not rare. The system needs a controlled exception path that is designed for reality:

• automatic status change to expired/ineligible at BUT,
• quarantine disposition for expired doses,
• reason coding (courier delay, equipment downtime, patient delay, scheduling change),
• investigation triggers when patterns repeat,
• waste linkage to controlled disposal records (see Radioactive Waste Log).

Tell it like it is: if expired doses are treated as “normal waste,” your program will hide systemic problems. Record the cause. Trend it. Fix the causes that create constant late doses. That’s the difference between operational control and perpetual firefighting.

13) Data integrity: audit trails and “no reconstruction” posture

BUT control must be credible. That means:

• unique user identities (no shared logins),
• auditable time stamps for anchor events (EOS, calibration, release),
• audit trails for edits with reason-for-change,
• system time governance (no local clock hacks),
• exception flags for late entry and backfills.

Tell it like it is: if you allow “time edits” without strong governance, you invite manipulation. The right posture is to make anchor times controlled events and prohibit casual edits. If a correction is necessary, it must be transparent, reviewed, and explained, not quietly applied.

14) Reconciliation: what you do with expired doses and returns

Expired doses don’t disappear. Your program must define controlled reconciliation:

• returns handling (identify, quarantine, evaluate eligibility, disposition),
• partial dose handling (residuals linked to the original dose ID),
• inventory adjustments (if your model tracks doses as inventory),
• waste conversion to defined waste streams with container IDs and decay rules,
• closed-loop proof that expired material was handled under control.

The point isn’t administrative neatness. The point is to prevent expired material from becoming a contamination risk or a record ambiguity. If a returned dose exists physically but not in your records, you created an accountability hole.

15) KPIs: proving time control is working

A BUT program without metrics becomes folklore. Minimal KPIs that actually tell the truth:

Tell it like it is: if expired dose rate rises and nobody changes the schedule model, the organization is normalizing failure. Use metrics to force reality: update routes, adjust batching, reduce staging delays, or change cutoff rules—whatever actually removes the cause.

16) Copy/paste readiness scorecard

Use this scorecard to check whether your BUT control is real in the busiest hour of the day.

17) Failure patterns: where BUT control collapses in real life

• Soft warnings only. People click through. Fix: hard gate expired status at pick/ship/use.
• Wrong anchor time. Teams disagree on “start time.” Fix: define anchor and enforce it everywhere.
• Time edits. “Correcting” time becomes normalization. Fix: protect anchors; make edits rare and reviewed.
• Staging drift. Doses sit “for a minute” and time margin disappears. Fix: dispatch rules + staging time caps.
• Transport optimism. Routes are assumed stable. Fix: measure dispatch margin; re-plan based on reality.
• Return ambiguity. Returned doses aren’t reconciled. Fix: quarantine + controlled disposition + linkage.
• Culture overrides. Patient pressure drives rule-bending. Fix: system-enforced stops and escalation rules.

All seven failures are predictable because the incentives are predictable. Time pressure always wins against polite reminders. Only enforced gates win against time pressure.

18) Validation posture: how you justify your BUT rule

A defensible BUT rule is not “because we’ve always done it.” It must be anchored in your validated process and operating model. Practical validation posture includes:

• defined process capability: show that your process produces doses with predictable quality within the usable window,
• instrument control: ensure measurement systems are verified (e.g., dose calibrator checks),
• labeling controls: prove the time window is communicated consistently and correctly,
• workflow enforcement: show that the rule is enforced at the point of action,
• deviation handling: show what happens when time windows are missed and how you prevent recurrence.

Tell it like it is: validation is not a paperwork event; it is proof that your operating model is stable. If the real-world workflow routinely cannot meet the window, the answer is not “ignore the window.” The answer is “change the workflow.”

19) Training and competency: stopping “we always do it this way”

Time rules fail when only a few people understand them. Training should be role-based and operational:

• operators: anchoring events, labeling discipline, and what constitutes an exception,
• dispatch/pickers: scan identity first, then verify time eligibility,
• couriers/handoffs: chain-of-custody confirmation and escalation when delayed,
• QA/RSO oversight: review expectations, trend analysis, and corrective action triggers.

Train to the rule: “expired is blocked” is not negotiable. Give people a clear escalation path when patient schedule pressure hits. If the only path is “make it work,” they will make it work. A strong program provides a controlled path: block, record, escalate, and re-plan.

20) How this maps to V5 by SG Systems Global

V5 supports BUT governance by making time eligibility enforceable across execution, quality, inventory, and integration—so BUT isn’t a label field, it’s a workflow gate:

• V5 MES enforces time-anchored execution events (e.g., EOS capture), links BUT to batch/dose identities, and blocks downstream steps when time eligibility fails.
• V5 QMS governs holds, pending results, and exception handling so conditional release never bypasses time boundaries; deviations and trends link to recurring expiry causes.
• V5 WMS supports scan-verified picking, staging, and dispatch gating so expired units cannot be picked or shipped, and returns can be quarantined and reconciled with controlled status.
• V5 Solution Overview describes how MES + QMS + WMS operate as one control system so time rules are enforced end-to-end rather than managed in spreadsheets.
• V5 Connect API enables integration of schedule, orders, and master data (and, when needed, customer/route constraints) so dispatch logic and time windows can be aligned to the real operating model.

In practice, this means BUT can be implemented as: defined anchor times, product-specific rules, real-time “expiring soon” visibility, and hard-gated blocks at release/pick/ship/use—plus controlled exceptions that record the truth and drive corrective actions instead of quiet workarounds.

21) Extended FAQ

Q1. Is beyond-use time the same as expiry time?
Not necessarily. Expiry can refer to stability dating. BUT is the operational eligibility boundary tied to the unit-of-use and the real workflow of short-lived products. Choose definitions that match your validated operating model and enforce them consistently.

Q2. What anchor time should we use—EOS or calibration time?
Use the anchor that is defined in your operating model and can be defended in records. EOS is often clean for manufacturing linkage. Calibration time is often essential for dose labels and clinical coordination. The key is consistency and controlled governance.

Q3. Are warnings enough?
No. Under patient and schedule pressure, warnings become noise. Use warnings for “expiring soon” and hard gates for “expired.” If you can bypass the gate, you don’t control the outcome.

Q4. What should we do with expired doses?
Treat them as controlled disposition: change status to expired, quarantine them, reason-code the cause, link to waste handling (container IDs and decay rules), and investigate repeating patterns. Don’t normalize expired doses as “just part of the day.”

Q5. What is the fastest improvement most sites can make?
Enforce a scan-first identity check at pick/dispatch and block shipping beyond BUT. That one control removes “wrong item” mistakes and forces the workflow to respect time boundaries.

Related Reading (keep it practical)
Build time control on clear anchors and enforced gates: End-of-Synthesis Time anchors production timing, Decay-Corrected Activity keeps activity decisions defensible, and Dose Calibrator Checks supports measurement credibility. If conditional release exists, keep time boundaries intact with Sterility Release Pending rules that do not override expiration gates. Close the loop by controlling expired dose disposition through Radioactive Waste Log and chain-of-custody discipline.