This is a ready-to-use checklist for a program moving a formulation from a vial toward a high-concentration prefilled syringe (PFS), typically to support subcutaneous administration. Work through it alongside the formulation team, the device/combination product engineer, and analytical development; do not treat it as a single-owner sign-off. Replace every <<FILL: ...>> placeholder with your own specifics. A filled specimen and instructions follow.
Document control header
| Field | Entry |
|---|---|
| Document title | High-Concentration PFS Formulation Readiness Checklist for <<FILL: product>> |
| Document number | <<FILL: e.g. PFS-RC-2026-03>> |
| Version | <<FILL>> |
| Target concentration / dose / volume | <<FILL>> |
| Checklist completed by | <<FILL: names, roles>> |
| Date | <<FILL>> |
1. Purpose
This checklist confirms that the formulation, fill and delivery systems, analytical methods, and container closure strategy have each been re-verified at the target high concentration for <<FILL: product>>, rather than carried forward unchanged from a lower-concentration vial formulation.
2. Checklist
| Item | Pass / Fail / NA | Evidence / notes |
|---|---|---|
| Target concentration and dose volume confirmed against the subcutaneous manual-injection ceiling (roughly 1 to 2 mL) | <<FILL>> | <<FILL>> |
| Viscosity characterized across the full concentration range planned, not only at the final target | <<FILL>> | <<FILL>> |
| Fill system (pump, nozzle) re-verified for accuracy at the target viscosity, not assumed from lower-concentration performance | <<FILL>> | <<FILL>> |
| Glide force / break-loose force characterized for the actual syringe, plunger, and formulation combination at target concentration | <<FILL>> | <<FILL>> |
| Siliconization method evaluated for particulate risk at target concentration; baked-on, cross-linked, or silicone-free options considered if risk is elevated | <<FILL>> | <<FILL>> |
| Assays requiring dilution validated with the dilution step included, not assumed equivalent to the undiluted method | <<FILL>> | <<FILL>> |
| Light-obscuration and other particle-counting methods checked for viscosity interference at target concentration | <<FILL>> | <<FILL>> |
| Self-association / reversible oligomerization characterized if applicable to this molecule at high concentration | <<FILL>> | <<FILL>> |
| Specifications and characterization protocols citing USP <788> confirmed to reference the current, retitled chapter (official August 1, 2026) | <<FILL>> | <<FILL>> |
| Container closure integrity strategy updated for the PFS’s two seal points (stopper and plunger), per USP <1207> | <<FILL>> | <<FILL>> |
| Extractables and leachables assessment updated for the syringe’s elastomer components at the reduced fill volume | <<FILL>> | <<FILL>> |
| Stopper and plunger seating force established as a validated process parameter, not an unverified assumption | <<FILL>> | <<FILL>> |
| If fill-finish runs at a CDMO, the above gaps fed into the CDMO’s technical assessment and equipment gap table | <<FILL>> | <<FILL>> |
3. Instructions
Complete every row with direct evidence, a study report, a validation record, a specification, not an assumption carried forward from the prior lower-concentration formulation. Any Fail blocks progression to the next development stage until closed or formally risk-accepted by Quality Assurance with a documented rationale. Revisit this checklist if the target concentration, device, or fill volume changes materially after initial completion.
4. Sign-off
| Role | Name | Signature | Date |
|---|---|---|---|
| Formulation lead | <<FILL>> | ||
| Device / combination product engineer | <<FILL>> | ||
| Analytical development | <<FILL>> | ||
| Quality Assurance | <<FILL>> |
5. References
USP General Chapter <788>, Subvisible Particulate Matter in Injections (official August 1, 2026). USP General Chapter <1207>, Package Integrity Evaluation, Sterile Products. ICH Q8(R2), Pharmaceutical Development.
Confirm the current version of each reference before issue.
Filled specimen
Extract from a readiness check for Acme Therapeutics’ ATX-410, moving from a 50 mg/mL vial presentation toward a 150 mg/mL prefilled syringe for subcutaneous self-administration.
| Item | Result |
|---|---|
| Viscosity across range | Characterized from 50 to 175 mg/mL; nonlinear rise confirmed above 120 mg/mL, informing the fill-system re-verification below |
| Fill system re-verification | Pump accuracy confirmed at 150 mg/mL target viscosity; original qualification at 50 mg/mL alone was not sufficient and would have been an incorrect basis for release |
| Siliconization | Standard sprayed silicone showed elevated subvisible particle counts in early studies at 150 mg/mL; moved to a cross-linked baked-on silicone application, which met acceptance |
| USP <788> citation check | Draft specification found still citing the prior chapter title; corrected before submission to reference the current, retitled chapter |
Result: three Fail items identified (fill system, siliconization, citation), all closed before progression, with the siliconization finding driving a real process change rather than a documentation fix alone.
Common inspection findings this checklist prevents
- A fill system’s accuracy assumed unchanged from a lower-concentration qualification, discovered wrong only after PPQ batches show fill variability.
- A siliconization method carried forward with no re-evaluation, producing a particulate finding late in development or at commercial scale.
- A specification still citing a superseded USP <788> chapter title after the August 2026 revision.
- Container closure integrity strategy left unchanged from a vial presentation, missing the PFS’s second seal point.
How to adapt this checklist
- Set your document number, product, and target concentration in the header.
- Add any device- or product-specific item your combination product strategy requires beyond the items listed.
- Require evidence, not an assumption, for every row; a Pass with no referenced evidence is not a real Pass.
- Route every Fail to a documented closure or a QA risk acceptance before progression.
- Confirm every reference in section 5 against the current published version before issue.