Vial stopper needle penetrability residual seal force and torque testing

Solution

• Force tester fitted with compression and penetration fixtures.
• Torque tester with grips to engage with small closure diameters

Benefits

• Enables comprehensive evaluation of injectable medicine container systems
• Allows multiple test methods to be conducted on a single platform.

Requirement

Parenteral products such as vaccines and other injectables are commonly filled into glass vials and closed with elastomeric stoppers and crimped aluminum caps. The purpose of these containment systems is to ensure sterility and avoid leaks and contamination during the shelf life.

The package integrity is described by the finishing phase of the product fill-finish process. The rubber stopper is compressed into the neck of the vial and held in place by the crimped aluminum cap. This system's performance is governed by the stopper's compression performance and the retention force provided by the cap.

One important measure of this performance, as a Container Closure Integrity (CCI) test, is the residual seal force (RSF). When measuring, the force testing system compresses the vials. The rubber stopper acts as a spring opposing the force. The breaking point of this resistance can be found on the force vs. displacement curve as the RSF value, which is an indicator of the seal's performance.

Torque retention of the crimp cap is another critical quality indicator. The vial is secured in a torque tester while rotational force is applied to the cap until it loosens. Lower torque values may indicate insufficient sealing pressure, often correlating with reduced RSF and compromised closure integrity.

Solution

In addition to the RSF, the protective flip-off cap must be considered. This should be sufficient to keep the cap in place during processing and shipping, but with the ability to remove it when needed. The removal force can be measured to assess if capping conditions are optimal to avoid damage to the retaining features or unintentional release.

Needle penetrability is another essential parameter. The force required for a hypodermic needle to pierce the rubber stopper must remain within defined limits to ensure smooth drug administration without damaging the needle. This is assessed using a penetration fixture integrated with a force testing system

Presto’s mechanical testing instruments combine force and torque measurement capabilities, enabling accurate and repeatable evaluation of all these parameters. These machines offer control, resolution, and repeatability for a range of vial and closure options.

For regulated environments, software integration supports secure data management, audit trails, and compliance with global regulatory expectations.

Test equipment

• Force test system for compression testing
• Torque test system for rotational evaluation
• Penetration and compression fixtures for vial stopper and cap testing

Test standards

• ISO 8362-7
• USP 1207.3