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Precise requirements

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Medical sterile products require the highest degree of packaging reliability. To achieve this involves validation of the packaging process and its result, and extensive documentation that complies with the relevant regulations. All the critical details of the packaging process are monitored and recorded and the process is qualified. Careful calibration of the central measuring devices is critical.

Comprehensive process monitoring

To guarantee the reproducible quality of the packaging process requires the capture and recording of the most important parameters. These are primarily the relevant process values for sealing: sealing pressure, temperature and duration. These three parameters are subject to a precise monitoring. The operator can adjust the values within the maximum preset permitted deviation. If this tolerance is exceeded, the faulty cycles are automatically expelled. If the error occurs in a series, the machine will stop, which means no faulty packages will be delivered.

With a thermoforming machine, the temperature in the forming station is monitored. In addition, the leak tightness of the formed packaging moulds can automatically be checked in the forming station itself or using a separate detecting station. This tightness monitoring is conducted using pressure and/or vacuum on the basis that the pressure or the vacuum may not change over a preset time period. If an error occurs, the automatic insertion of the product into the defective mould is prevented and the cycle is automatically expelled.

Sealing pressure is a critical factor for a stable and clean sealed seam. To guarantee reproducibility of this parameter, it is monitored precisely by means of an additional pressure transducer in the sealing die. The sealing time is initially calibrated; during the operation, the internal clock of the machine control system serves as a reference. The sealing temperature can be measured in the sealing die in a precise and reproducible manner with calibrated resistance thermometers.

There can be additional inspections such as a check for empty packages by means of photo cells. Here, too, there can be an automatic expulsion of faulty cycles. In addition, there are frequent checks for potentially protruding products using pivoted “fingers” or flaps. These are on the same level as the package and cause the machine to stop if they are lifted. This prevents problems in the sealing die before they occur. Correct labelling is crucial for a medical package. Different printing systems are employed depending on the specific requirements of the application. Finally, printing is controlled by systems such as digital fibreoptic sensors or a machine vision system.

Validation in compliance with ISO EN 11607: 2006

Qualification and validation are decisive components of process reliability. Qualification refers to the process of demonstrating that the system is capable of fulfilling the specified requirements. Validation is establishing documented evidence that provides a high degree of assurance that a specific process will consistently produce a product that meets its predetermined specifications and quality attributes. For the packaging of sterile medical products that are sterilised after the packaging process, the authoritative standard is ISO EN 11607: 2006.¹ The regulation presumes a quality management system and risk analysis in advance, and the operator of the system is responsible for the proof.

All test and protocol steps specified in ISO EN 11607: 2006 for the validation and qualification are the responsibility of the medical device manufacturer. To an increasing degree, machine manufacturers directly support medical device manufacturers in their validation. The machine manufacturer may offer a complete “validation package” according to ISO EN 11607: 2006 to qualify the packaging process. This package contains documentation of all functions and potential risks together with the proof of process suitability. Risk analysis is employed in which possible risks are systematically identified and evaluated in connection with the machine. In addition, the following services may be offered:

Design qualification

• Project specific validation plan
• Duty book/functional specification
• Hardware design specification
• Software design specification

Installation qualification

• Inspection of the equipment
• Comparison of the planning documents with the installed condition of the finished machine

Operational qualification

• Test of the product relevant components and component groups
• Test of the machine specific software modules
• Error test protocols.

The importance of calibration

Calibration is the determination of systematic deviations in measurements. In this process, certain measuring and regulating procedures are examined for deviations in measurements according to the requirements of the medical device manufacturer. Then the deviations can be compensated for by setting up an offset.

The calibration applies to temperature, pressure and vacuum sensors. The results are recorded in a calibration protocol of the initial calibration. The same protocol also describes the procedure for a recalibration. The operator receives a template for recalibration on a CD, which provides the required material to repeat the calibration regularly. However, recalibration is complex and it is recommended that the machine manufacturer supports the calibration process, particularly in smaller machine facilities.

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Matthias Ehrat is Division Manager Sales, Jürgen Steinbauer is Global Validation Manager, Heinz Wegmann is Manager Medical Packaging, e-mail: muwo@multivac.de at Multivac, Bahnhofstrasse 4, D-87787 Wolfertschwenden, Germany, tel. +49 8334 6010 www.multivac.com