In ophthalmic manufacturing, the primary container isn’t simply something that holds the formulation. It protects the product, forms part of the contamination-control strategy and ultimately becomes the interface through which the patient receives the dose. For BFS applications, this makes container design an important technical consideration.
Container Closure Integrity
For a sterile ophthalmic product, achieving sterility during manufacture is only part of the challenge. That state needs to be appropriately maintained throughout the intended shelf life of the product. Container closure integrity (CCI) is therefore a critical consideration for BFS products.
The ability of the finished container to provide an appropriate microbial and physicochemical barrier needs to be demonstrated rather than assumed simply because the container was formed and sealed within a BFS machine.
Current EU GMP Annex 1 is explicit for containers closed by fusion: BFS units and small-volume containers (100 mL or less) should undergo 100% integrity testing using validated methods. Visual inspection alone is not considered an acceptable integrity test.
Integrity therefore becomes part of the validated manufacturing process, not merely a development check. Mould condition, parison and wall-thickness control, mould temperature, sealing parameters, flash removal and downstream handling can all influence the integrity of the finished unit.
Polymer Selection
The polymer used to manufacture the BFS container must also be evaluated in relation to the formulation.
Considerations can include:
- Product compatibility
- Extractables and leachables
- Barrier properties
- Stability
- Mechanical performance
- Processing characteristics
The suitability of the container therefore depends on the interaction between the material, BFS process and pharmaceutical product.
For small-volume polyolefin BFS containers, permeability can be especially important because the ratio of container surface area to fill volume is high. Moisture transmission through a semipermeable polymer can cause water loss and potentially change product concentration during shelf life. Depending on the formulation, gas and light barrier performance may also require evaluation.
FDA’s December 2023 draft guidance recommends water-loss testing for ophthalmic products in semipermeable container closure systems and evaluation of the protection provided by any secondary packaging. An overwrap may therefore be a functional part of the overall container closure system, not merely a presentation layer.
Container Geometry
For ophthalmic products, geometry can also affect functionality. Tip design, opening characteristics, container flexibility and dispensing behaviour can all influence how the product performs when it reaches the patient.
This is where BFS tooling becomes particularly interesting. The mould isn’t simply creating the outer appearance of the package; it is producing a functional part of the drug-delivery system.
CCI and Regulatory Expectations
Container closure systems continue to receive considerable regulatory attention.
FDA’s December 2023 draft guidance for topical ophthalmic drug products addresses microbiological quality, extractables and leachables, stability, and the design, delivery and dispensing characteristics of the container closure system.
More recently, FDA’s August 2026 draft guidance, Container Closure Systems for Human Drugs and Biological Products, again highlights the need for a risk-based evaluation of the suitability and quality of pharmaceutical container closure systems.
For BFS manufacturers, the direction is clear: The container needs to be considered as part of the product not simply the output of the filling machine.
Bringing Everything Together
Ophthalmic BFS therefore requires manufacturers to think beyond fill volume and production speed.
Successful ophthalmic BFS development connects formulation compatibility, polymer selection, extrusion and moulding parameters, seal integrity, shelf-life barrier performance and dispensing function. None of these elements can be evaluated reliably in isolation.
And that brings us to the final question in this series.....
Once the product and container requirements have been established, how do you determine which BFS system is actually suitable to manufacture it?