Stabilized sustained release tramadol formulations

The stabilized sustained release oral solid dosage form of 6, wherein said hydrophobic polymer comprises from about 0% to about 80% by weight, of the hydrophobic material.

The stabilized sustained release oral solid dosage form of 6, wherein said hydrophobic polymer comprises from about 30% to about 50% by weight, of the hydrophobic material.

A process for preparing a stabilized sustained release oral solid dosage form containing tramadol as the active agent, comprising

• preparing a matrix comprising tramadol or a pharmaceutically acceptable salt thereof dispersed in a matrix of a hydrophobic material comprising a substance which is melted or softened during the preparation of said matrix;
• and thereafter
• curing said matrix at a temperature from about 35° C. to about 65° C. for a sufficient time such that an endpoint is reached at which said matrix provides a stable dissolution profile, said endpoint being determined by comparing the dissolution profile of said matrix immediately after curing to the dissolution profile of said matrix after exposure to accelerated storage conditions of at least one month at 40° C. and 75% relative humidity.