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Time-dependence of pressure in lyophilization vials
1Electro-Technic Products, Inc., Chicago, Illinois.
PDA Journal of Pharmaceutical Science and Technology
|July 1, 1994
Summary
Vacuum testing of lyophilized pharmaceuticals reveals vial pressure increases over time due to water vapor desorption from stoppers. This impacts seal integrity and moisture content, crucial for quality assurance.
Area of Science:
- Pharmaceutical Sciences
- Materials Science
- Analytical Chemistry
Background:
- Lyophilized pharmaceuticals require robust packaging for stability.
- Vacuum testing is a critical quality assurance step for sealed vials.
- Understanding internal vial pressure is essential for assessing seal integrity.
Purpose of the Study:
- To measure internal vial pressure (Pv) over time after sealing under reduced pressure.
- To identify the primary sources of pressure increase in lyophilization vials.
- To evaluate the impact of product and vial characteristics on pressure changes.
Main Methods:
- Measurement of internal vial pressure in 50 mL and 10 mL vials (with and without product) over 2300 hours.
- Analysis of outgassing and permeation of vial stoppers (O2, NH3, H2O).
- Correlation of pressure rise with stopper material properties and product hydrophilicity.
Main Results:
- Internal vial pressure increased to ~2 torr within 50 hours and reached 5-10 torr by 2300 hours.
- Water vapor desorption from the stopper was identified as the main contributor to pressure rise.
- Hydrophilic products slowed pressure increase; smaller vials showed faster pressure rise.
Conclusions:
- Stopper material significantly influences internal vial pressure and moisture levels.
- Pressure changes provide insights into seal integrity and potential product degradation.
- Further investigation into stopper materials and their interaction with pharmaceutical products is warranted.