Leveraging Hot Melt Extrusion for Solubility and Continuous Manufacturing

Hot melt extrusion (HME) technology has become a key solution to adding absorption for enhanced solubility. HME is also a continuous process, which has been encouraged by the FDA.1 Companies lacking in this particular expertise are encouraged to seek out a firm with proven authority in the space, such as Foster Delivery Science.  

Foster Delivery Science operates out of a 32,000-square-foot GMP manufacturing facility. The plant was constructed in 2015 and took about 16 months to become fully commissioned and qualified. By the first quarter of 2017, the plant was operational and producing clinical supply batches. Foster Delivery Science was born out of Foster Corporation, which was founded in 1989 with a focus on serving the healthcare industry with custom  biomedical polymers. Due to our leadership position in this market, Foster’s customers began requesting drug/polymer blending about 15 years ago. Pharmaceutical companies learned of this capability and began making similar requests. Foster Delivery Science became a subsidiary of Foster Corporation to better meet this need. At Foster Delivery Science, we are focused on polymer-based drug delivery technologies requiring HME and are dedicated to innovating polymer and process technologies required for drug delivery applications.

To top our own constantly improving standards, Foster Delivery Science is continually upgrading. Most recently, we added cryogenic milling capability. Cryogenic milling is key for blending polymers and APIs in order to minimize particle separation. We are a polymer-focused company, and although polymers do not mill easily — for example, implant polymers that are used for drug delivery such as ethylene-vinyl acetate (EVA) and thermoplastic polyurethane (TPU) polymers — we’ve found success cryogenic milling both polymer types. To better our processes and create solutions, we turn to cryogenic milling as an initial step, prior to combining the polymer with the drug. We then melt-blend the drug in a twin-screw extrusion step; this is followed by a single screw-step necessary for the shaping involved in drug delivery implant production. 

Cryogenic milling is key for blending polymers and APIs in order to minimize particle separation. 

More than a Solubilization Strategy

We pride ourselves on our niche expertise. HME is our core drug delivery technology. We leverage our proficiency in this technology, not only as a solubilization strategy but also as a means to create various dosage forms. Our extensive work in extrusion is also applied to other drug delivery techniques — we have GMP processes in place to produce a pellet or a powder through extrusion and milling, or to create a rod and monofilaments, films, tubes and profile shapes. Another example of how we elevate our capabilities is in twin-screw extrusion, which is highly modular, as both the barrels and screws are programmable. 

At Foster Delivery Science, we take a very pragmatic approach to developing processes centered on our client’s valuable API. As we are backed by Foster Corporation, we benefit from the best of both worlds — we enjoy the flexibility and nimbleness that comes from being a small company, as well as the resources present in our sister organization. This backing has helped Foster Delivery Science to grow organically, always motivated to build on our prior successes. 

Clinical to Commercial

We take pride in our work, which begins with our client’s clinical supply programs. We are able to fully support these programs as they progress through to commercial and are trusted with a client’s valuable project from the very beginning of formulation to whenever the drug goes off the market. 

Ultimately, extrusion itself is a part of a continuous manufacturing process. It can be bookended by API continuous manufacturing on one end and, on the other, by the tableting or the insertion of the implant into an applicator or a final packaging. When a client walks through our door, they know continuous manufacturing is possible — batches are not required. As continuous manufacturing is an initiative that is constantly being pushed by the FDA, this adds another layer to why our clients are already at an advantage when working with us in this process. 

As extrusion experts, we are confident that, when a client begins formulation development, we are supplying a product that is going to be accepted for approval. 


  1. Pharmaceutical Excipients for Hot-Melt Extrusion.” PharmTech 35.5 (2011). Web.

Tony Listro

Tony has worked in the polymer industry for more than 20 years in technical management positions, responsible for polymer processing and polymer formulation. Tony has more than 10 years' experience in the pharmaceutical field, holding two issued U.S. patents and authoring / co-authoring more than fifteen publications.