Title:The Production of Solid Dosage Forms from Non-Degradable Polymers
Volume: 22
Issue: 19
Author(s): Ian Major, Evert Fuenmayor and Christopher McConville
Affiliation:
Keywords:
Controlled release, hot-melt extrusion, EVA, silicone elastomer, thermoplastic polyurethane, implants.
Abstract: Non-degradable polymers have an important function in medicine. Solid dosage forms for longer term
implantation require to be constructed from materials that will not degrade or erode over time and also offer the
utmost biocompatibility and biostability. This review details the three most important non-degradable polymers for
the production of solid dosage forms – silicone elastomer, ethylene vinyl acetate and thermoplastic polyurethane.
The hydrophobic, thermoset silicone elastomer is utilised in the production of a broad range of devices, from urinary
catheter tubing for the prevention of biofilm to intravaginal rings used to prevent HIV transmission. Ethylene
vinyl acetate, a hydrophobic thermoplastic, is the material of choice of two of the world’s leading forms of contraception
- Nuvaring® and Implanon®. Thermoplastic polyurethane has such a diverse range of building blocks that
this one polymer can be hydrophilic or hydrophobic. Yet, in spite of this versatility, it is only now finding utility in
commercialised drug delivery systems. Separately then one polymer has a unique ability that differentiates it from the others and can be
applied in a specific drug delivery application; but collectively these polymers provide a rich palette of material and drug delivery options
to empower formulation scientists in meeting even the most demanding of unmet clinical needs. Therefore, these polymers have had a
long history in controlled release, from the very beginning even, and it is pertinent that this review examines briefly this history while
also detailing the state-of-the-art academic studies and inventions exploiting these materials. The paper also outlines the different production
methods required to manufacture these solid dosage forms as many of the processes are uncommon to the wider pharmaceutical industry.
