Critical Parameters Affecting Process Validation

Validation is an integral part of quality assurance; it involves systematic study of systems, facilities and processes aimed at determining whether they perform their intended functions adequately and consistently as specified. Validation in itself does not improve processes but confirms that the processes have been properly developed and are under control. Adequate validation is beneficial to the manufacturer in many ways – It deepens the understanding of processes; decreases the risk of preventing problems, defect costs, regulatory non compliances and thus assures the smooth running of the process.

Process Validation is key to a robust manufacturing process

Process validation involves a series of activities taking place over the lifecycle of product and process. Validation requires a meticulous preparation and careful planning of the various steps in the process. All work involved should be carried out in a structured way according to formally authorized standardized working procedures.

What are the Critical Parameters affecting Process Validation?

The critical parameters should normally be identified during the development stage or from historical data or during manufacturing and process control. Process validation involves three stages and now will identify the critical parameters in these stages.

Stage One: Process Design

Process design is the activity of defining the commercial manufacturing process. The goal of this stage is to design a process suitable for routine commercial manufacturing that can consistently deliver a product that meets its critical quality attributes. A product development activity provides key inputs to the design stage, such as the intended dosage form, the quality attributes, and a general manufacturing pathway. The functionality and limitations of commercial manufacturing equipment should be considered, also contributions of variability by different component lots, production operators, environmental conditions and measurement systems in the production setting.
Designing an efficient process with an effective process control approach is dependent on the process knowledge. Use of risk analysis tools to screen potential variables for Design of Experiment (DOE) studies to minimize the total number of experiments. The results of DOE studies can provide justification for establishing ranges of incoming component quality, equipment parameters and in-process material quality attributes. Manufactures should document the variables studied for a unit operation and the rationale for those variables identified as significant. This information is useful during the process qualification and continued process verification stages, including the design is revised or strategy for control is refined.
Process control addresses the variability to assure quality of the product. Controls can consists of material analysis and equipment monitoring at significant processing points designed to assure that the operation remains on target and in control with respect to output quality. Timely analysis, control and adjust the processing conditions so that the output remains constant.

Stage Two: Process Qualification

During this stage, the process design is confirmed as being capable of reproducible commercial manufacturing. It confirms that all established limits of the critical parameters are valid and that satisfactory products can be produced even under worst case condition. This stage has following elements –Qualification of Utilities and Equipment.
Installation Qualification is an essential step preceding the Process Validation exercise which is normally executed by Engineering group. The installation of equipment should follow well defined plans which is developed and finalized following progression through a number of design stages. This stage of validation includes examination of Equipment Design, Determination of Calibration, Maintenance and Adjustment Requirements.
Consider the following Equipment Calibration Requirements
1. Confirmation of calibration of calibrating equipment with reference to the appropriate national standard.
2. Calibration of measuring devices utilized in the Operational Qualification stage.
3. Identification of calibration requirements for measuring devices for the future use of the equipment. At the Installation Qualification stage the company should document preventive maintenance requirements for installed equipment.
Operational Qualification is an exercise oriented to engineering function referred as commissioning. It is important stage to assure all operational test data conform with pre-determined acceptance criteria and manufacturer should develop draft standard operating procedures for the equipment, service operation, cleaning activities, maintenance requirements and calibration schedules.
The critical operating parameters for the equipment or the plant should be identified at the Operational Qualification stage. Critical variables should incorporate specific details and tests that have been developed. The completion of a successful Operational Qualification should include the finalization of operating procedures and operator instructions documentation for the equipment.
Performance Qualification combines the actual facility, utilities, equipment, trained personnel, control procedures and components to produce commercial batches. Performance qualification will have a higher level of sampling, additional testing and greater scrutiny of process performance. The level of monitoring and testing should be sufficient to confirm uniform product quality throughout the batch during process.

Stage Three: Continued Process Verification

Continually assure that the process remains in a state of control during commercial manufacturing. A system or systems for detecting unplanned departures from the process as designed is essential. The following points to be considered in Continued Process Verification.
Collection and evaluation of information and data about the performance of the process will allow detection of process drift. Evaluation should determine whether action must be taken to prevent the process from drifting out of control.
An ongoing program to collect and analyze product and process data that relate to product quality must be established to verify the critical quality attributes are being controlled throughout the process.
Process variation also can be detected by assessment of defect complaints, out of specifications finding, process deviation reports, process yield variations, batch records, incoming raw material records and adverse event reports.
Operator’s errors should be tracked to measure the quality of the training program.
Maintenance of the facility, utilities and equipment is an important aspect of ensuring that a process remains in control.

Conclusion

Process validation is a mean of ensuring and documenting that the processes are capable of producing a finished product of the required quality consistently and should cover all the critical elements of the manufacturing process. The process design stage and the process qualification stage should have as a focus the measurement system and control loop establishing scientific evidence that the process is reproducible and will consistently deliver quality products.
Good process design and development should anticipate significant sources of variability and establish appropriate detection, control, appropriate alert and action limits. Process variability should be periodically assessed. It is the responsibility of the manufacturer to judge and provide evidence of a high degree of assurance in its manufacturing process.

References

• Guidance for Industry Process Validation: General Principles and Practices – US Dept. of Health and Human Services, Food and Drug Administration. Nov. 2008 Current Good Manufacturing Practices.
• ANNEX 15. Validation Master Plan, Design Qualification, Installation and Operational Qualification, Non Sterile Process Validation, Cleaning Validation. 17th Sep. 1999.