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Inner Diameter of Hypodermic Needles: A Critical Factor in Prefilled Syringe Design
Remo Eugster1,2, Cormac McCrea1, Simon Knappke3
1Novartis Pharma AG, WSJ-204/1/100, CH-4002 Basel, Switzerland.
PDA Journal of Pharmaceutical Science and Technology
|July 11, 2026
Summary
Controlling the hydrodynamic inner diameter (IDh) of prefilled syringe needles is crucial for autoinjector performance. Accurate measurement systems ensure consistent injection times and successful drug delivery, enhancing patient experience.
Area of Science:
- Pharmaceutical device development
- Drug delivery systems
- Quality control in manufacturing
Background:
- The hydrodynamic inner diameter (IDh) of staked-in needle prefilled syringes (PFS) significantly impacts autoinjector performance.
- Variations in IDh can lead to a 30% fluctuation in injection times, affecting drug delivery accuracy.
Purpose of the Study:
- Evaluate measurement systems for detecting IDh variations in incoming goods control.
- Assess the impact of IDh variability on PFS performance and patient outcomes.
Main Methods:
- Measurement system analysis (MSA) combined with micro-computer tomography.
- Round robin studies to compare different IDh measurement techniques.
- Analysis of IDh variations across different PFS batches and manufacturers.
Main Results:
- A semi-automated measurement system was identified as suitable for accurate and reliable IDh measurement.
- Statistically significant IDh variations (259–300 µm) were found in 27 G thin wall needles.
- IDh control is essential to prevent variable injection times and device stalling in autoinjectors.
Conclusions:
- Implementing robust IDh measurement and control is vital for pharmaceutical device development.
- Consistent IDh ensures predictable injection times, improving patient experience and treatment success.
- Controlling needle parameters directly benefits overall therapeutic efficacy.