The present technology relates to an extended-release solid oral pharmaceutical composition, comprising a cured blend of a melt-extruded first component and a second component, wherein the melt-extruded first component comprises a therapeutically effective amount of an opioid or a pharmaceutically acceptable salt thereof, at least one PEO polymer, and a stabilizing agent; and the second component comprises at least one PEO polymer and an oxidative stabilizing agent. The extended-release pharmaceutical compositions of the present technology provide crush-resistant and abuse-deterrent formulations featuring enhanced heat stability, resistance to drug segregation, and resistance to alcohol-induced dose dumping.