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6/3/2011 | 2 MINUTE READ

Bridging the Gap Between Plastics...and Medicine

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Foster is believed to be first plastics compounder to venture into pharmaceutical.

For the past decade, the pharmaceutical industry has begun to look at ways to shift medicine making—also known as drug delivery—from a batch to continuous process. The same twin-screw compounding technology that has been employed in plastics for years is beginning to penetrate the pharmaceutical industry.

At last month’s SPE ANTEC event in Boston, Charlie Martin, general manager of Leistritz in Somerville, N.J., estimated that roughly 120 to 130 twin-screw machines have been sold to pharmaceutical makers within the last 10 years.

In drug mixing, the continuous extrusion process obviously offers production benefits over batch processing. But there are other benefits as well. It is estimated that roughly half of the drugs in use today are both highly crystalline in structure and poorly soluble. These features impact their ability to be absorbed in the bloodstream and perform their intended task. Twin-screw extrusion creates a drug that is amorphous and bioactive, meaning that it is absorbed into the body much more quickly.
For the most part, pharmaceutical companies who have opted for twin-screws have taken production in-house. A few have outsourced to compounders that have sprung up to mix drugs and only drugs.


Foster Corp. is believed to be the only compounder with roots in plastics to expand into pharmaceuticals, and has a dedicated business unit, Delivery Science, at its Putnam location to provide services for highly regulated products. Delivery Science three twin-screw Leistritz lines and two single-screw machines from CW Brabender, S. Hackensack, N.J., in a Class 7 static clean room.

Delivery Science also provides materials for implantable applications. These include blends of polymers and bioactive fillers such as tricalcium phosphate (TCP), hydroxyapatite (HA), and biphasic calcium phosphate (BCP) to make them osteoconductive, meaning that bone will grow on and bond to the polymer.

Implantable polymers such as PEEK are used in permanent implants, often in high-stress applications. Bioresorbable polymers such as polycaprolactone (PCL), PLA, and polyglycolide (PGA) are used in implants for temporary support while the body heals and ultimately replaces the implant with natural bone. For optimum implant device performance, Foster customizes bioresorbable polymers for absorption in one to 36 months and flexural modulus from 30,000 psi (200 MPa) to over 1,000,000 psi (6900 MPa).

Records of all process parameters are meticulously maintained during development and manufacturing trials. All manufacturing components are calibrated and equipment is cleaned per GMP standards.

The group offers its implantable polymers to processors in multiple delivery forms for use in a variety of applications. For implantable materials, most of its customers are injection molders. Formulations are available in a variety of pellet sizes for processing in standard or micromolding equipment. In extrusion, medicine can actually be delivered through embedding it in the walls of a customer’s multi-lumen or coextruded tubing.

It remains to be seen whether more plastics compounders will follow Foster’s lead into pharmaceuticals. Leistritz’s Martin is skeptical, reasoning that “it’s easier for a pharmaceutical company to get their arms around twin-screw extrusion than it is for a plastics compounder to get their arms around pharmaceuticals.”  Still, with extrusion still in its infancy in pharmaceutical manufacturing, it could be an area high-tech plastics compounders will want to explore.