KLOW Stack

All glass vials undergo a full triple-wash cycle using endotoxin-free USP Water for Injection (WFI). Vials are then depyrogenated in a dry-heat oven at 250 °C for a minimum of 30 minutes, eliminating all pyrogens and biological residue to below detectable limits. Each vial is individually screened for particulate matter and surface contamination prior to entering the filling line. Any vial failing inspection is permanently quarantined.

Each peptide is synthesised via Solid Phase Peptide Synthesis (SPPS) using Fmoc/tBu orthogonal protecting group chemistry on a validated automated synthesiser. Upon synthesis completion, the raw peptide bulk undergoes mandatory HPLC purity testing and ESI mass spectrometry to confirm molecular identity and amino acid bond integrity at every position. Batches failing to achieve ≥ 99.0% HPLC purity are rejected and destroyed — none are downgraded or blended.

The purified peptide solution is snap-frozen at −80 °C using liquid nitrogen-assisted cooling. Primary drying removes bulk water at −40 °C under 100 mTorr vacuum; secondary drying at +25 °C / 50 mTorr removes residual bound moisture. Final water content is confirmed < 5.0% by Karl Fischer titration. Lyophilisation preserves the peptide in its structurally most stable solid state, eliminating degradation pathways active in aqueous solution.

All filling operations are conducted exclusively inside an ISO Class 5 (EU GMP Grade A equivalent) cleanroom maintained under continuous positive nitrogen gas pressure. The environment is HEPA-filtered to ≤ 3,520 particles ≥ 0.5 μm per cubic metre, with continuous real-time particle monitoring. Vials are filled under a closed vacuum — no atmospheric air contacts the lyophilised product at any point during filling. Operators are fully gowned; zero bare skin contact with any vial or product surface.

Immediately post-filling, vials are transferred — without human handling — to an automated robotic sealing station. Each vial receives a bromobutyl rubber stopper and a pharmaceutical-grade aluminium overseal applied by a servo-controlled crimping head. Crimp torque is electronically verified on 100% of units to ±0.05 N·m precision. A dye ingress challenge test is periodically conducted on sealing samples, confirming hermetic closure under elevated atmospheric pressure.

Every single vial is individually inspected under a 365 nm UV-A illumination chamber. UV exposure causes any microbial contamination, extraneous protein, or fluorescent compounds to emit a characteristic visible fluorescence — enabling immediate rejection of affected units with zero tolerance. Vials also pass through white and black background visual stations for particulate matter and seal assessment. Any unit displaying fluorescence, visible particles, discolouration, or seal anomaly is permanently quarantined.

A statistically representative sample from each completed batch undergoes final release testing: endotoxin by LAL chromogenic assay, sterility by USP <71> membrane filtration (14-day incubation, dual media), particulate matter by USP <788> light obscuration, and a final HPLC purity re-confirmation. This Certificate of Analysis is issued only upon full numerical pass of every specification. All batch records are archived for a minimum of 5 years and are traceable to the lot number printed on each vial label.