CA2270975C — Stabilized sustained release tramadol formulations

USPTO Abstract

A stabilized sustained release oral solid dosage form which includes an effective amount of tramadol or a pharmaceutically acceptable salt thereof dispersed in a matrix of a hydrophobic material comprising a wax-like substance which was melted or softened during the preparation of the matrix, is cured at a temperature from about 35 ~C to about 65 ~C for a time period from about 4 to about 72 hours, such that the formulation, when subjected to in vitro dissolution after exposure to accelerated storage conditions of at least one month at 40 ~C/75 % RH, releases an amount of tramadol which does not vary at any given dissolution time point by more than about 20 % of the total amount of tramadol released when compared to in vitro dissolution conducted prior to subjecting the dosage form to the accelerated storage conditions.