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Updated: May 25, 2026

The Quantification of Injectability by Mechanical Testing
Published on: May 13, 2020
Variability in syringe components and its impact on functionality of delivery systems
Nitin Rathore1, Pratik Pranay, Bruce Eu
1Drug Product and Device Development, Amgen, Thousand Oaks, CA.
Prefilled syringes and autoinjectors are increasingly common for drug delivery. This study analyzes how component variability impacts injection forces, developing a model for robust device design.
Area of Science:
- Pharmaceutical Engineering
- Biomedical Device Design
- Drug Delivery Systems
Background:
- Prefilled syringes and autoinjectors offer patient convenience and improved dose accuracy for parenteral drug administration.
- Autoinjectors enhance usability by enabling self-administration, reducing patient hesitation through features like needle shielding.
- Successful commercialization hinges on understanding component variability and its effect on device performance.
Purpose of the Study:
- To investigate the impact of variability in primary container and device components on injection forces.
- To evaluate the influence of barrel size, needle size, autoinjector spring force, and frictional forces on delivery performance.
- To develop an analytical model for characterizing the design space of autoinjector systems.
Main Methods:
- Component variability analysis for prefilled syringes and autoinjectors.
- Evaluation of key parameters including barrel size, needle size, spring force, and friction.
- Development of a physics-based analytical model to predict device functionality.
Main Results:
- Variability in syringe and autoinjector components significantly affects injection delivery forces.
- Key factors influencing delivery forces include barrel dimensions, needle gauge, spring force, and friction.
- The developed analytical model provides a framework for predicting autoinjector performance.
Conclusions:
- Understanding and quantifying component variability is crucial for robust autoinjector design.
- The analytical model aids in optimizing device design and ensuring consistent drug delivery.
- This work supports the successful development and commercialization of advanced parenteral drug delivery systems.
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Dosage Regimen: Individualization
Parenteral Drug Delivery Systems: Injectables, Implants, and Infusion Devices
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Modified-Release Drug Delivery Systems: Drug Release Characteristics
Drug Delivery Systems: Different Types

