Blow-Fill-Seal (BFS) advanced aseptic process

Eye drops, saline solutions but also anti-asthmatic drugs are part of the products that can be found on the market today in the form of sterile single doses. Unither is mainly specialized in this field of unit-dose around two technologies: Blow-fill-seal (BFS) and liquid stick-packs. In 2020, when the company recorded sales of €330 million, 3.4 billion BFS doses and 500 million liquid stick-packs were manufactured.

The story of Amiens historical plant 

The company’s origins lie in a 17-person plant in Amiens (Somme), which was acquired from Sanofi in 1993. It was this transaction that led to the creation of Unither. Today, the company has seven production sites: five in France, one in Brazil and one in the United States, and counts nearly 1,600 employees. The Amiens plant, the company’s historical birthplace, remains the company’s bridgehead. With 420 employees and covering an area of 16,230 m2, the plant specializes in Blow-fill-seal (BFS) technology. Unither serves three main markets: ophthalmology, asthma and rhinology. Amiens works for these three markets with a fairly strong focus on asthma and rhinology.

Manufacturing steps

It is the following BFS steps that prove the expertise of the plant. This technology consists of forming, filling and sealing the unit dose in a single manufacturing step. Pharmaceutical grade low density polyethylene (PE) is stored in granular form in silos outside the building. The plant consumes several thousand tons each year. The PE is transported to the BFS packaging lines. It is then heated in extrusion screws to 220-230°C and blown into the molds of the BFS machine. The bottom part of the unit dose is formed. Needles are then filled with the drug before a new PE blowing step to form the upper part of the package and seal the container. A few seconds are enough to create and fill a strip or gob of 10 doses attached to each other. All these operations allow to obtain a perfectly sterile product. The PE is extruded at a very high temperature, which ensures its sterility. The drug undergoes two filtrations, one of which is sterilizing before filling. And the BFS steps take place under a sterile air shower. The medication in the unit-dose is therefore sterile by construction.

Once the gobs have been made, they move to the debottlenecking step. This involves separating the single doses. The PE scraps are then recovered to be sold for further use. The single-doses are directed into a tiered conveyor. The next step is to check the single-doses, first with level detection and then with a leak test, to ensure the integrity of the dose. The single-dose containers can then be labeled. Some products then go through a bagging step. For small volumes of less than 5 ml, the single-doses are bagged for stability reasons. The smaller the volume, the more exchanges with the surface, which reduces the delay for the expiration date. Being in a pouch protects the product from light.


The plant manufactures single-dose products from 0.25 ml to 10 ml. All products are then directed to a checkweigher and then a cartoner. The lines are equipped for serialization. Although the cartons and labels are specific to the manufacturer’s customer, the shape of the single-dose is the same for all. The BFS machines are thus each dedicated to a format. However, several lines work with the same format, which makes it possible to produce on several lines at the same time. In order to combine convenience for the patient and productivity for the manufacturer, we sought to optimize the shape of the dose to have a good compromise. We have therefore dedicated each machine to a dose. The customer differentiation is made on the number of doses in a case and in the leaflet and the case. So the shaper has kept some standardization of packaging while developing expertise around the sterile single-dose.

The Amiens site is set to grow, with currently 13 BFS lines. Continued investments allow them to provide innovative solutions to their customers in over 100 countries.