Production of sterile pharmaceutical products

In short: Sterile products are manufactured using a product-specific, validated route that controls microbial, particulate and endotoxin or pyrogen contamination. The route may use terminal sterilisation after filling, or aseptic processing when the product cannot undergo terminal sterilisation.

Choose the manufacturing route for the product

Sterile manufacture is not synonymous with aseptic manufacture. India’s revised Schedule M distinguishes products sterilised in their final container from processes conducted aseptically at some or all stages (Drugs Rules, 1945, Schedule M, Part II, §1.3). EU GMP Annex 1 recommends terminal sterilisation of the finished product when the product can tolerate it, because this generally provides greater assurance of sterility than sterile filtration and/or aseptic processing (Annex 1 (2022), §8.34).

The choice depends on the formulation, container-closure system, product stability and validated process. A method that is suitable for one material may damage another. It is therefore inaccurate to assume that every raw material is sterilised by autoclaving, filtration or irradiation, or that every sterile product follows the same sequence.

Terminal sterilisation

In this route, the product is filled into its final container, the container is closed, and the finished product undergoes a validated sterilisation process. The selected equipment and cycle must be supported by scientific data showing that the process is repeatable and reliable for the product and load. Critical parameters are defined, controlled, monitored and recorded (EU GMP Annex 1 (2022), §§8.35–8.40).

The process must also control contamination before the sterilisation step. Product preparation, filling conditions, components and equipment are selected according to the assessed risks and the product-specific process. Schedule M, Part II, §4.11.1 describes separate environmental approaches for terminally sterilised products, with preparation and filling conditions depending on the product and contamination risk. Do not apply cleanroom grades or cycle settings from another product as universal values.

Aseptic processing

Use an aseptic route when the product cannot undergo terminal sterilisation, or where the authorised manufacturing process requires aseptic manufacture. The product, product-contact equipment, containers and closures must be prepared so their required sterile state is achieved and maintained through filling and closure. For a liquid that is suitable for sterile filtration, the filtration process and filter system require validation; filtration is not a universal treatment for all formulations (EU GMP Annex 1 (2022), §§8.80–8.95).

Aseptic control depends on the whole system, including facility and equipment design, personnel training, utilities, material controls, container-closure controls, cleaning and disinfection, process validation, environmental monitoring and investigation of adverse results. These elements should be considered together in the contamination control strategy (EU GMP Annex 1 (2022), §§2.1–2.7). India’s Schedule M also requires sterile preparations to be made in suitable clean areas, with access and operations arranged to control contamination (Part II, §§1.1–1.2 and 4.1).

An aseptic process simulation, often called a media fill, periodically checks whether the aseptic controls can perform effectively under simulated production conditions. Annex 1 states that this simulation is not the primary means of validating the process; process design, the pharmaceutical quality system, process controls, training and monitoring data also contribute to assurance (EU GMP Annex 1 (2022), §§9.32–9.38). See the media-fill validation SOP for a related overview.

Contamination control and batch assessment

Sterility assurance is built into process design and execution. Monitoring and finished-product testing provide evidence about control, but neither should be relied on by itself to assure sterility (EU GMP Annex 1 (2022), §§2.1–2.7 and 10.5). Schedule M, Part II, §§2.1–2.3 likewise treats the sterility test as one measure in a series and calls for review of processing records and, for aseptic processing, environmental-quality records alongside test results.

Before a batch is assessed for release, the authorised quality system should evaluate the approved process evidence, including applicable sterilisation or filtration records, environmental and process-monitoring results, test results, deviations and investigations. The specific acceptance criteria and release responsibilities come from the product’s authorised dossier and the site’s approved procedures; this article does not set universal limits.

Related reading: sterile-product facility and clean-area classification and sterility testing of pharmaceutical products.

Frequently asked questions

Is every sterile product made by aseptic processing?

No. A product may be terminally sterilised in its final container when the product and packaging can tolerate a validated process. Aseptic processing is used when terminal sterilisation is not suitable or when the approved process requires it.

Can all raw materials be sterilised using the same method?

No. Material properties and their role in the process determine which preparation or sterilisation method is suitable. Use only methods established and validated for the material and product.

Does a passing sterility test alone prove that a batch is sterile?

No. The test is one part of a wider control strategy. Process validation, routine controls, monitoring and batch-record assessment are also important to sterility assurance.

References

• European Commission. EudraLex Volume 4, EU Guidelines for Good Manufacturing Practice, Annex 1: Manufacture of Sterile Medicinal Products (2022 revision), §§2, 8–10. Official Annex 1 PDF.
• Government of India, Ministry of Health and Family Welfare. Drugs Rules, 1945, Schedule M, substituted by G.S.R. 922(E), 28 December 2023, Part II. Official Gazette notification.