Hot-melt extrusion using a compounding extruder to blend medicine with water-soluble polymers is a growing area for the pharmaceutical industry, according to speakers at Antec 2010.
Speakers from machinery, research and pharmaceutical firms explained hot-melt extrusion in a technical session May 18 at the Society of Plastics Engineers' annual conference in Orlando.
The technology is similar to traditional plastics compounding, but with a few big differences, according to Charlie Martin, general manager of American Leistritz Extruder Corp. The extruder supplier in Somerville, N.J., has targeted the pharmaceutical sector.
Running sample quantities is a challenge, because 10 grams of a medical ingredient can cost $50,000, he said.
It required, we found, a different way of thinking and a different mind-set, Martin said. We're not trying to go faster, we're trying to conserve. We're trying to get every gram out of the process.
Leistritz developed the Nano-16 micro extruder with a micro-plunger feeder, to meet the challenge of starve-feeding an extruder with tiny amounts of material. A tiny plunger puts the material into the extruder, and then it goes through a strand pelletizer and is milled and pressed into tablets or capsules.
Another difference: Some pharmaceutical officials prefer single-piece screws instead of the traditional segmented screws, Martin said, because they think they are easier to clean, making it easier to obtain FDA validation.
Hot-melt extrusion emerged when the Food and Drug Administration encouraged drug makers to use continuous manufacturing processes, Martin said.
Compounding extrusion is a good fit, and it's proven, he told Antec attendees. I encourage anyone that's in the pharmaceutical industry to take solace in the fact that this technology is very battle-hardened and robust and has been used for 10, 20, 30, 40 years, in 24-hours-a-day/seven-day operations, he said.
American Leistritz will conduct a pharmaceutical extrusion seminar June 16-17 that includes demonstrations at its process lab.
Costas Gogos said the amazing diversity of polymer molecules and blends makes hot-melt extrusion attractive to drug companies.
It is in the infinity of polymer structures that makes polymers what is called a 'willing bride,' to be married to all sorts of other materials, said Gogos, a research professor of chemical engineering at the New Jersey Institute of Technology and a co-founder of the Polymer Processing Institute.
Matching up materials is exactly what happens. The active pharmaceutical ingredient is dissolved into the polymer matrix, where it has to remain in a stable condition, Gogos said. He called the process scientific compounding.
Craig McKelvey of Merck & Co. Inc. explained that oral medicine is absorbed through the stomach lining, but insoluble drugs present a challenge and are good candidates for hot-melt extrusion.
McKelvey, a senior investigator at Merck's research laboratories in West Point, Pa., described how the company pairs medicines and specific polymers for extrusion.
He said injection molding also will play a role in new shapes of medicine. For example, injection molding could make a unique shape of heart pill that is clear and heart-shaped. That would avoid confusion by people who take several medications a day.
Those types of elegant and unique pills also would limit counterfeit medicine, he said.
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