Coextrusion Line Demonstrates Technology for API Catheters
At trade show, suppliers team to show how to run a medical tube that includes medicine.
Three machine builders teamed at last month’s MD&M West Show in Anaheim to show the technology necessary to extrude catheters with active pharmaceutical ingredients (API) as a thin outside layer. At the show, two ¾-in extruders from Davis-Standard, furnished with upstream dryers and downstream cooling/pulling/cutting technology from Conair Group, and a Zumbach Electronics three-axis OD laser gauge, ran a TPU demonstrating how API can be coextruded in a thin layer on the outside of the plastic tube. Typical applications could include the addition of an antimicrobial outer layer to prevent formation of biofilm that can cause infection, or an anticoagulant to avoid catheter thrombosis.
The three machine builders co-exhibited in a single booth at the show, where they were joined by Leistritz a leader in supply twin-screw extrusion lines for API compounding.
At the show, the main body of the catheter tube—a single-lumen adult PICC line with an OD of 0.067 in.—was made of clear TPU delivered by the primary ¾-in Davis extruder. A second ¾-in. extruder delivers blue-colored resin to represent the API. The inner/outer layer ratio was approximately 80/20. Each extruder was furnished with a gear pump that fed a cross-head co-extrusion die supplied by Guill Tool & Engineering .
“The same technology that can add color to the surface layer of medical tubing also can be used to apply a pharmaceutically active ingredient like silver sulfadiazine,” explains Bob Bessemer, sales manager, Medical Extrusion for Conair. “For the demonstration, we are using color instead of an API, but the process is exactly the same.”
Bessemer adds: “When the line includes single-screw extruders, the API would need to be pre-compounded into the resin or delivered as a masterbatch. But if you use a twin-screw extruder for the pharmaceutical-layer material, you can actually combine the neat API into the polymer in-line with the rest of the process.” Leistritz also furnishes lines that combine twin-screw compounding and production of sheet, tubing, and other extrusions in a single step.
An estimated $9.8 billion is spent each year treating hospital-acquired infections (HAIs), according to a study published in 2013 by JAMA Internal Medicine. Sources at medical-tubing processors acknowledge that the technology to produce catheters with API is readily available. But as numerous experts Plastics Technology has spoken with on this subject point out, including API adds cost to the catheter, and hospitals by and large have been unwilling to pay extra for the medical device before a comprehensive study is conducted proving their benefits. Tubing formulated with API would also be subjected to extensive and expensive FDA validation procedures.
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