What Is Process Analytical Technology?

Pharmaceutical scientific female researcher in protective uniform working with dissolution tester at pharmacy industry manufacture factory laboratory Process analytical technology
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In August 2002, the FDA announced the initiative called Process Analytical Technology (PAT) as a cornerstone of “Pharmaceutical Current Good Manufacturing Practices (CGMPs) for the 21st Century—a Risk Based
Approach”. You might then ask what is this?

The initiative was a regulatory framework started by the FDA to encourage the pharmaceutical industry to improve the process of pharmaceutical development, its manufacturing and quality control.

The aim of PAT was to improve process control and efficiency by defining Critical Process Parameters (CPP) and monitoring these CPPs to stay within a defined limit, either in-line or on-line to maintain a product’s Critical Quality Attributes (CQA) .

Process analytical technology (PAT) is succinctly defined as:-

‘Systems for analysis and control of manufacturing processes based on timely measurements of critical quality parameters and performance attributes of raw and in-process materials’.

It has also been formally defined by the United States Food and Drug Administration (FDA) as a ‘mechanism to design, analyze, and control pharmaceutical manufacturing processes through the measurement of Critical Process Parameters (CPP) which affect Critical Quality Attributes (CQA).. A good introduction to this topic is through a review by Rathore et al., (2010).

Critical Quality Attributes (CQA)

Critical Quality Attributes (CQAs) are specific physical, chemical, biological, or microbiological properties or characteristics that should be within an appropriate limit, range, or distribution to ensure the desired product quality. The measurement and control of CQAs are paramount in biopharmaceutical manufacturing processes to ensure the safety, efficacy, and consistency of the final product. Here’s a discussion on the use of measurements of CQAs in biopharmaceutical manufacturing:

Identification of Critical Quality Attributes (CQAs)

The first step is to identify which attributes of the biopharmaceutical product are critical for its quality, safety, and efficacy. This is often done through a combination of scientific understanding, risk assessment, and regulatory requirements. CQAs can include attributes such as purity, potency, stability, structural integrity, and biological activity.

Measurement Techniques

Various analytical techniques are employed to measure CQAs throughout the manufacturing process. These techniques are often highly specialized and tailored to the specific attributes being measured. Examples include chromatography (e.g., HPLC, GC), mass spectrometry, spectroscopy (e.g., UV-Vis, IR, NMR), electrophoresis, bioassays, and imaging techniques. These methods allow for the quantification, characterization, and assessment of critical quality attributes.

In-process Control

Measurements of CQAs are performed at various stages of the manufacturing process to ensure that the product meets quality specifications at each step. In-process control involves monitoring critical quality attributes in real-time or at specified intervals to detect deviations from target values or trends that could indicate process variability. This allows for timely adjustments to process parameters to maintain product quality and consistency.

Release Testing

Prior to product release, comprehensive testing of CQAs is conducted to confirm that the finished product meets predetermined specifications. Release testing includes a thorough assessment of critical quality attributes to ensure that the product is safe, effective, and of consistent quality. These tests may be performed using validated analytical methods in accordance with regulatory requirements.

Quality by Design (QbD)

QbD (Quality by Design) principles emphasize the systematic approach to product development and manufacturing, focusing on understanding and controlling the sources of variability that impact critical quality attributes. Measurements of CQAs play a central role in QbD by providing data-driven insights into the relationship between process parameters and product quality. This enables manufacturers to design robust processes that consistently produce high-quality products.

Continuous Improvement

Measurement data from CQAs are used to drive continuous improvement efforts in biopharmaceutical manufacturing. By analyzing trends, identifying root causes of deviations, and implementing corrective and preventive actions, manufacturers can enhance process efficiency, reduce variability, and optimize product quality over time.

Regulatory Compliance

Accurate measurement and control of CQAs are essential for regulatory compliance in the biopharmaceutical industry. Regulatory agencies such as the FDA and EMA require manufacturers to demonstrate control over critical quality attributes to ensure product safety, efficacy, and consistency. Comprehensive documentation of measurement methods, validation protocols, and data integrity is necessary to meet regulatory standards.

So what can we say about CQAs? The measurement of critical quality attributes is a cornerstone of biopharmaceutical manufacturing, ensuring that products meet the highest standards of quality, safety, and efficacy. Through careful identification, measurement, and control of CQAs, manufacturers can produce biopharmaceuticals that consistently meet patient needs and regulatory requirements.

Process Parameters

A process parameter is one whose variability impacts on a critical quality attribute. It must be monitored or controlled to ensure the process generates the desired quality.

Critical Process Parameters

In biopharmaceutical manufacturing, critical process parameters (CPPs) are key variables that can significantly affect the quality, safety, and efficacy of the final product. Measurement and control of these parameters are essential to ensure consistency and reproducibility in the manufacturing process. Critical process parameters (CPP) in pharmaceutical manufacturing are key variables affecting the production process. They are summed up as operating parameters that are essential for maintaining product output within specified quality target guidelines. 

Identification of Critical Process Parameters (CPPs)

The first step is to identify which parameters have a critical impact on the quality of the product. This is often done through risk assessment and process understanding, considering factors such as product stability, efficacy, and safety.

Measurement Techniques

Various measurement techniques are employed to monitor CPPs throughout the manufacturing process. These techniques can include analytical methods such as chromatography, spectrophotometry, mass spectrometry, and immunoassays, among others. These methods allow for the quantification and characterization of critical parameters such as concentration, purity, molecular weight, and structural integrity of the biopharmaceutical product.

Real-time Monitoring

Continuous or real-time monitoring of CPPs is preferred whenever feasible. This allows for immediate detection of deviations from the desired process conditions, enabling prompt corrective action to maintain product quality. Advanced sensors and online analytical technologies play a crucial role in real-time monitoring, providing instantaneous feedback on critical parameters.

Control Strategies

Measurement data from CPPs are used to implement control strategies aimed at maintaining process parameters within predefined ranges. Control strategies may include feedback control loops, where measurements are used to adjust process conditions in real-time, or feedforward control strategies, where predictive models are used to anticipate and preemptively adjust process parameters.

Process Optimization

Measurement data from CPPs are also valuable for process optimization efforts. By analyzing historical process data and identifying correlations between CPPs and product attributes, manufacturers can refine their processes to enhance product quality, increase yield, and reduce manufacturing costs.

Regulatory Compliance

Accurate measurement and control of CPPs are essential for regulatory compliance in the biopharmaceutical industry. Regulatory agencies such as the FDA and EMA require manufacturers to demonstrate control over critical aspects of the manufacturing process to ensure product safety and efficacy. Comprehensive documentation of measurement methods, instrument calibration, and data integrity is necessary to meet regulatory standards.

Risk Mitigation

Monitoring and controlling CPPs help mitigate risks associated with process variability and deviations. By ensuring that critical parameters remain within specified limits, manufacturers can reduce the likelihood of product failures, batch rejections, and regulatory non-compliance.

We can say after all that the measurement of critical process parameters is fundamental to ensuring the quality, safety, and consistency of biopharmaceutical products. Through accurate measurement, real-time monitoring, and effective control strategies, manufacturers can optimize their processes while meeting regulatory requirements and delivering high-quality products to patients.

Critical Process Parameters: The Relation To Critical Quality Attributes

Those attributes with a higher impact on CQAs should be prioritized and held in a stricter state of control. The manufacturer should conduct tests to set acceptable range limits of the determined CPPs and define acceptable process variable variability. Operational conditions within this range are considered acceptable operational standards. Any deviation from the acceptable range will be indicative of issues within the process and the subsequent production of substandard products. Data relating to CPP should be recorded, stored, and analyzed by the manufacturer. CPP variables and ranges should be reevaluated after careful analysis of historical CPP data. Identifying CPPs is done in stage one of Process Validation: Process design are an essential part of a manufacturing control strategy.

One method of defining CPPs is to look at the effect of certain production processes on critical quality attributes. Those production parameters which have a measurable effect on those quality attributes are of most significance because of this attribute.

The concept actually aims at understanding the processes by defining their CPPs, and accordingly monitoring them in a timely manner (preferably in-line or on-line) and thus being more efficient in testing while at the same time reducing over-processing, enhancing consistency and minimizing rejects.

PAT can provide better process control and result in better process understanding. It may also alter the approach to setting in-process specifications, e.g. measuring constant purity instead of yield. Although it is not likely to eliminate validation, the effort spent to incorporate PAT, especially for a new product or for a process change, can enhance manufacturing consistency and reduce failed batches—providing an economic advantage.

The FDA has outlined a regulatory framework for PAT implementation. With this framework, according to Hinz, the FDA tries to motivate the pharmaceutical industry to improve the production process. Because of the tight regulatory requirements and the long development time for a new drug, the production technology is “frozen” at the time of conducting phase-2 clinical trials.

Generally, the PAT initiative from FDA is only one topic within the broader initiative of “Pharmaceutical cGMPs for the 21st century – A risk based approach”.

The Basics Of Process Analytical Technology

PAT is a term used for describing a broader change in pharmaceutical manufacturing from static batch manufacturing to a more dynamic approach.

The desired state of pharmaceutical manufacturing as defined in the PAT guidance is as follows:

  • Product quality and performance are ensured through the design of effective and efficient manufacturing processes.
  • Product and process specifications are based on a mechanistic understanding of how formulation and process factors affect product performance.

  • Continuous real-time QA is done throughout the process.

  • Risk-based regulatory approaches recognize the level of scientific understanding of how formulation and manufacturing process factors affect product quality and performance and the capability of process control strategies to prevent or mitigate the risk of producing a poor-quality product.

PAT requires defining the Critical Process Parameters (CPPs) of the equipment used to make the product, which affect the Critical Quality Attributes (CQAs) of the product and then controlling these CPPs within defined limits. This allows manufacturers to produce products with consistent quality and also helps to reduce waste & overall costs.

This mechanism for producing consistent product quality & reducing waste presents a good case for utilising continuous manufacturing technologies. The control of a steady state process when you understand the upstream & downstream effects is an easier task as common cause variability is easier to define and monitor.

Variables In Process Analytical Technology (PAT)

It would be acceptable to consider that raw materials used to manufacture pharmaceutical products can vary in their attributes e.g. moisture content, crystal structure etc. It would also be acceptable to consider that manufacturing equipment does not always operate in exactly the same fashion due to the inherent tolerance of the equipment and its components. It is therefore logical to say that variability in raw materials married with a static batch process with inherent variability in process equipment produces variable product. This is on the basis that a static batch process produces product by following a fixed recipe with fixed set-points.

With this in mind the PAT drive is to have a dynamic manufacturing process that compensates for variability both in raw materials & equipment to produce a consistent product.

Process Analytical Technology Implementation (PAT)

The challenge to date with PAT for pharmaceutical manufacturers is knowing how to start. A common problem is picking a complex process and getting mired in the challenge of collecting and analysing the data.

The following criteria serve as a basic framework for successful PAT roll-outs: (From A PAT Primer)

  • Picking a simple process. (Think Water for Injection (WFI) or Building Monitoring System (BMS)
  • All details and nuances are well understood and explained for that process.
  • Determine what information is easily collected and accessible through current instrumentation.
  • Understanding the appropriate intervals for collecting that data.
  • Evaluating the tools available for reading and synchronizing the data.

PAT Tools

In order to implement a successful PAT project, a combination of three main PAT tools is essential:

  • Multivariate data acquisition and data analysis tools: usually advanced software packages which aid in design of experiments, collection of raw data and statistically analyzing this data in order to determine what parameters are CPP.
  • Process analytical chemistry (PAC) tools: in-line and on-line analytical instruments used to measure those parameters that have been defined as CPP. These include mainly near infrared spectroscopy (NIRS); but also include biosensors, Raman spectroscopy, fiber optics and others.
  • Continuous improvement and/or knowledge management tools: paper systems or software packages which accumulate Quality Control data acquired over time for specific processes with the aim of defining process weaknesses and implementing and monitoring process improvement initiatives. These products may be the same or separated from the statistical analysis tools above.

Long-term goals

The long-term goals of PAT are to:

  • reduce production cycling time
  • prevent rejection of batches
  • enable real time release
  • increase automation and control
  • improve energy and material use
  • facilitate continuous processing

Currently NIR spectroscopy applications dominate the PAT projects. A possible next-generation solution is Energy Dispersive X-Ray Diffraction (EDXRD). 

Although the FDA’s PAT initiative encourages process control based on the real-time acquired data, a small part of PAT applications goes beyond monitoring the processes and follows the PACT (‘Process Analytically Controlled Technology’) approach.


Fundamental to process analytical technology (PAT) initiatives are the basics of multivariate analysis (MVDA) and design of experiments (DoE). This is because analysis of the process data is a key to understand the process and keep it under multivariate statistical control.

What Are The Challenges Faced By Those Adopting Process Analytical Techniques?

Adopting process analytical techniques (PAT) in biopharmaceutical manufacturing presents several high-level challenges that need to be addressed to ensure successful implementation. The challenges as I see it are:-

Complexity of Biopharmaceutical Processes

Biopharmaceutical manufacturing processes are often complex and involve a multitude of interconnected variables. Implementing PAT requires a deep understanding of these processes and their critical parameters, as well as the development of analytical methods capable of capturing the relevant data in real-time or near real-time.

Integration with Existing Infrastructure

Incorporating PAT into existing manufacturing infrastructure can be challenging. It may require significant modifications to equipment, instrumentation, and control systems to enable seamless data acquisition, integration, and analysis. Compatibility with legacy systems and processes must also be considered to minimize disruptions and ensure continuity of operations.

Validation and Regulatory Compliance

Ensuring the reliability, accuracy, and reproducibility of PAT data is essential for regulatory compliance. Validating PAT methods and demonstrating their equivalence to traditional offline analytical methods can be complex and resource-intensive. Regulatory agencies such as the FDA and EMA require robust documentation of validation protocols, data integrity, and compliance with current good manufacturing practices (cGMP).

Data Management and Analysis

PAT generates large volumes of data in real-time, which must be managed, processed, and analyzed effectively. Establishing robust data management systems capable of handling high-throughput data streams, ensuring data integrity, and extracting actionable insights is crucial. Advanced analytics techniques such as multivariate data analysis (MVDA) and machine learning may be required to derive meaningful information from complex PAT datasets.

Skill and Expertise Requirements

Implementing PAT necessitates specialized knowledge and expertise in analytical chemistry, instrumentation, data science, and process engineering. Training personnel and building internal capabilities to design, implement, and maintain PAT systems can be challenging, particularly in organizations with limited experience in advanced analytical techniques.

Cost and Resource Allocation

The upfront costs associated with acquiring, installing, and validating PAT equipment and infrastructure can be substantial. Additionally, ongoing maintenance, calibration, and support requirements must be budgeted for. Allocating resources effectively and demonstrating the return on investment (ROI) of PAT implementation are critical considerations for decision-makers.

Risk Management

Introducing new analytical techniques into biopharmaceutical manufacturing processes carries inherent risks related to data integrity, process reliability, and product quality. Implementing robust risk management strategies to identify, assess, and mitigate potential risks is essential to minimize the impact of unforeseen issues on product quality and patient safety.

Addressing these high-level challenges requires a holistic approach that encompasses technical expertise, organizational readiness, regulatory compliance, and strategic planning. Collaboration between cross-functional teams, including scientists, engineers, quality assurance professionals, and regulatory experts, is essential to navigate the complexities of PAT implementation effectively.

How is industry implementing Process Analytical Technology (PAT)?

The implementation of Process Analytical Technologies (PAT) in the biopharmaceutical industry has been steadily evolving, driven by advances in analytical instrumentation, data analytics, and regulatory expectations.

The Current Implementation of PAT

Real-time Monitoring and Control

Many biopharmaceutical manufacturers are leveraging PAT to monitor critical process parameters (CPPs) in real-time or near real-time. This allows for immediate detection of deviations and enables proactive adjustments to maintain process robustness and product quality.

Multivariate Data Analysis (MVDA)

MVDA techniques are being used to analyze complex datasets generated by PAT systems. These techniques help identify correlations between process parameters and product attributes, enabling manufacturers to optimize process conditions and enhance product quality and consistency.

Quality by Design (QbD) Approach

PAT is integral to the QbD approach, which emphasizes a systematic understanding of the relationship between process variables and product quality. By incorporating PAT early in the product development lifecycle, manufacturers can design more robust processes and reduce the need for extensive testing and validation.

Advanced Sensor Technologies

The development of advanced sensor technologies, such as spectroscopy, chromatography, and imaging techniques, has enabled real-time monitoring of key process parameters without the need for offline sampling. These sensors provide continuous feedback on critical quality attributes, allowing for tighter process control and faster decision-making.

Integrated PAT Systems

There is a trend towards integrating PAT systems directly into manufacturing equipment and control systems, enabling seamless data acquisition, analysis, and control. Integrated PAT solutions streamline workflow, reduce manual intervention, and facilitate real-time process optimization.

What Does The Future Hold For Process Analytical Technology?

Advanced Analytics and Artificial Intelligence (AI)

The future of PAT is likely to involve greater use of advanced analytics and AI techniques to extract actionable insights from complex data streams. Machine learning algorithms can analyze large datasets, predict process outcomes, and optimize process parameters autonomously, leading to more efficient and adaptive manufacturing processes.

IoT and Industry 4.0 Integration

PAT (Process Analytical Technology) systems will become increasingly interconnected as part of the broader Industry 4.0 framework. Internet of Things (IoT) technologies will enable remote monitoring and control of manufacturing processes, facilitating real-time decision-making and adaptive manufacturing strategies.

In-line and In-situ Measurements

There will be a continued shift towards in-line and in-situ measurement techniques, minimizing the need for manual sampling and offline analysis. This trend will enable continuous monitoring of critical quality attributes throughout the manufacturing process, improving process efficiency and product consistency.

Miniaturization and Portable PAT Devices

Advances in miniaturization and portable instrumentation will enable PAT systems to be deployed directly at the point of manufacturing, including in bioreactors and downstream processing units. These compact devices will provide real-time feedback on process performance, enabling rapid intervention and optimization.

Regulatory Harmonization and Standardization

Regulatory agencies are expected to continue promoting the use of PAT through guidance documents and initiatives aimed at harmonizing regulatory expectations globally. Standardization of PAT methodologies, data formats, and validation protocols will facilitate adoption and compliance across different regions and jurisdictions.

Overall, the future of PAT in biopharmaceutical manufacturing will be characterized by greater integration, automation, and intelligence, enabling manufacturers to achieve higher levels of process understanding, control, and optimization. By embracing emerging technologies and adopting innovative strategies, the industry can drive continuous improvement in product quality, efficiency, and patient outcomes.


Rathore, A. S., Bhambure, R., & Ghare, V. (2010). Process analytical technology (PAT) for biopharmaceutical products. Analytical and Bioanalytical Chemistry398, pp. 137-154 (Article)

U.S. Department of Health and Human Services, Food and Drug
Administration (2002) http://www.fda.gov/Drugs/Development
GoodManufacturingPracticescGMPforDrugs/UCM071836 (no longer accessible)

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