Good Practices for Air Handling Units (AHU) in Pharmaceutical Manufacturing

Air Handling Units (AHU) :Air quality is one of the most critical aspects of pharmaceutical manufacturing. Contaminants in the air can negatively impact the quality and safety of pharmaceutical products. This is why Air Handling Units (AHUs) are essential to controlling the environment within pharmaceutical facilities. Proper design, installation, monitoring, and maintenance of AHUs are crucial to ensuring that they operate efficiently and in compliance with Good Manufacturing Practices (GMP).

This article outlines the best practices for AHUs in pharmaceutical manufacturing, focusing on design, installation, operation, and maintenance to ensure clean and safe air quality for production areas.

Key Good Practices for AHU Design and Installation

1. Compliance with Guidelines

The AHU system should be designed in compliance with the requirements set forth in the New Schedule ‘M’ or any other applicable regulatory guidelines. These standards ensure that the AHU meets the necessary requirements for air filtration, pressure, and air quality needed in pharmaceutical production areas.

1. Appropriate Installation

Installing window A/C systems without proper air filtration and pressure control is not acceptable. The AHU should be properly designed, fabricated, and installed in accordance with its design qualification (DQ). Detailed records of the design and installation process should be maintained and made readily available for future reference.

1. Proper Location and Space

AHUs should be installed in a clean, appropriate location with enough space around the unit for easy cleaning and maintenance. A well-maintained space is crucial to preventing the accumulation of contaminants around the unit, which could compromise air quality.

1. Use of Correct Filter Sizes

It is vital that the AHU is equipped with the correct size filters to ensure the desired class of air quality is met. Separate AHUs should be used for different areas of the manufacturing process to prevent cross-contamination.

1. Effective Temperature and Humidity Control

Temperature and humidity controls should be PLC-based (Programmable Logic Controller) and fully automated. Additionally, an alarm system must be installed to alert personnel in case the system operates outside the specified conditions, allowing for timely corrective actions.

1. Material of Construction

The construction materials used for the AHU should be easily cleanable and should not contribute to contamination. Materials should be resistant to corrosion and other environmental factors while remaining durable over time.

1. Ensuring Cleanability of the AHU Design

The AHU design should ensure ease of cleaning. All internal components should be accessible for regular cleaning without requiring disassembly or complicated procedures.

1. Adequate Filtration in Return Air Ducts

Return air ducts, especially in areas with high dust generation (e.g., tablet manufacturing or powder processing), should be equipped with high-efficiency filters to prevent contamination from circulating in the facility.

1. Validation Before Use

Before using the AHU system for production, the unit should undergo proper validation, including Design Qualification (DQ), Installation Qualification (IQ), Operational Qualification (OQ), and Performance Qualification (PQ). The validation process should be well-documented and accompanied by Standard Operating Procedures (SOPs).

Operational Good Practices for AHUs

1. Training and Documentation

Personnel responsible for AHU operations should receive proper training on good practices for AHU operation, maintenance, and troubleshooting. Additionally, records of training sessions should be maintained for compliance and traceability purposes.

1. SOPs for AHU Operation

Detailed SOPs for AHU operation, cleaning, and maintenance should be established and displayed near the AHU units. This ensures that all personnel are following the correct procedures and can quickly refer to the guidelines if needed.

1. Preventive Maintenance and Periodic Cleaning

AHUs should undergo regular preventive maintenance and periodic cleaning to ensure they continue to function at optimal levels. Cleaning schedules and maintenance records must be maintained to document compliance with regulatory requirements.

1. Proper Pressure Control and Airflow Patterns

For facilities that produce parenteral products or other sensitive formulations, AHUs should be designed with proper differentiated pressure to maintain airflow patterns from cleaner to dirtier areas. This helps to prevent contamination in sterile environments. The design should also account for the necessary air changes per hour, heat load, and occupancy levels.

1. System Fabrication Quality

The AHU and associated ductwork should be fabricated with high-quality materials and installed without any leaks. Proper installation minimizes the risk of contamination from air leakage and helps maintain the integrity of the air supply.

1. Duct and Diffuser Design

Detailed drawings of the system layout, including the types of ducts, diffusers, grills, elbows, and branching, should be readily available. These drawings ensure that the system is installed according to specifications and provides the correct airflow distribution.

1. Monitoring and Measurement of Air Quality Parameters
   The AHU system should be equipped with instruments that measure temperature, humidity, pressure, and air velocity. These parameters should be regularly monitored to ensure that the air quality remains within the desired range. Recordings of these parameters should be kept for compliance purposes.
2. Airflow Velocity and Filter Integrity

Manometers should be installed to monitor the pressure differential inside the room and ensure that airflow velocity meets the required standards. The pressure drop across the filters should be maintained and recorded to verify filter integrity and ensure optimal filter performance.

1. Dust Management

Dust produced in the manufacturing process should be captured and not allowed to escape into the atmosphere. Exhaust systems should be properly designed to prevent contaminants from escaping into the surrounding environment.

1. Disinfection and Maintenance Between Production Cycles

The AHU and the surrounding area should be disinfected when there is a gap between production activities to prevent contamination. This is particularly important in cleanrooms and areas where sterile products are manufactured.

Validation and Compliance in AHU Systems

1. Systematic Validation Process

The validation process for AHU systems should follow a structured approach, ensuring that the system is fully compliant with pharmaceutical manufacturing standards. Validation steps should include:

1. • Calibration and certification of test equipment
   • Calibration of AHU-related equipment
   • Verification of utilities (e.g., water, power supply)
   • Testing of control parameters
   • Alarm system testing
   • HEPA filter integrity testing
   • Airflow velocity testing
   • Smoke studies and pressurization testing
   • Qualification of temperature and humidity control systems
   • Microbial monitoring (both viable and non-viable counts)
2. Documentation and Logs

All validation steps should be thoroughly documented in logs and records. This includes maintaining qualification reports, test results, and SOPs to ensure full traceability during inspections or audits.

Conclusion

Maintaining a high level of air quality is crucial to ensuring the safety, effectiveness, and quality of pharmaceutical products. By following Good Practices for Air Handling Units (AHUs), pharmaceutical manufacturers can ensure that their facilities meet the strict regulatory requirements for air quality and contamination control.

Proper design, installation, and maintenance of AHUs are key to ensuring that the air supplied to manufacturing areas remains free from contaminants. These practices, combined with continuous monitoring, validation, and personnel training, help maintain the integrity of the manufacturing environment and, ultimately, the quality of the pharmaceutical products produced.