Similarities and Differences between the Serum and Lyophilization Stoppers

Feature NumberaSerumLyophilizationImpact on CCIRationale
Key similarities1Stopper formulationMajorStopper formulation and outer diameter of the plug can potentially impact CCI, so they were kept constant for this comparison.
2Outer diameter of the plugMajor
Key differences3Flange thickness over the vial finish is slightly thicker than that of the lyophilization stopper by about 3%Flange thickness over the vial finish is slightly thinner than that of the serum stopper by about 3%MinorThe flange thickness difference between the serum and lyophilization stoppers is not expected to be significant because this difference is minor and possibly within dimension tolerances.
4Dimpled top center of flangeFlat flangeMinorFlange thickness over the vial finish, as noted in #3, is comparable.
5No fluoropolymer film on top of flangeFluoropolymer film present on top of flangeMinor/noneFluoropolymer film is very thin and provides smoothness to the top of the stopper; no film is on the stopper land seal.
6Plug geometry:Concave feature inside plug, minimal structural supportFluoropolymer film placement results in shorter valve seal of 0.71 mmPlug geometry:Vent and legs provide structureFluoropolymer film placement results in longer valve seal of 0.95 mmMajorLyophilization stopper plug may form better valve seal with glass compared with serum stopper plug owing to structural support from the lyophilization stopper and placement of fluoropolymer film.
  • a Refer to Figure 2 for a comparison of the numbered features of the serum and lyophilization stoppers.