Mechanical Characterization of Thermally Annealed Tablets Containing Polyethylene Oxide for Abuse Deterrence

The abuse of prescription opioid drugs is a well-documented and very serious problem. One of the typical first steps an abuser will take is to manipulate a tablet into to a fine powder. To deter this behavior, formulators use crush-resistant technologies like polyethylene oxide (PEO). When heat-treated, PEO creates a hard, flexible tablet that cannot be easily ground down into a fine powder. We investigated the effects of PEO molecular weight (MW), annealing temperature, and annealing time on tablet compression deformation behavior and fracture resistance. These tests were designed to represent an abuser's attempt to smash and grind a tablet, respectively. Annealing temperatures above the melting point of PEO showed the most improvement in mechanical properties compared with that in unannealed tablets. The minimum annealing time was dependent on the polymer MW and annealing temperature. Tablets were manipulated using a coffee grinder, and the particle size of the resulting powders was measured. The particle size correlated well with fracture toughness, demonstrating that increasing fracture toughness increases the manipulation resistance of a PEO tablet.