The use of a controlled release matrix material selected from the group consisting of hydrophilic and hydrophobic polymers, digestible long chain hydrocarbons and polyalkylene glycols in the manufacture of a solid oral dosage form comprising a therapeutically effective amount of an opioid analgesic in a controlled release matrix comprising at least one of said controlled release matrix materials, wherein said opioid analgesic is selected from the group consisting of hydromorphone oxycodone, morphine, levorphanol, methadone, meperidine, heroin, dihydrocodeine, codeine, dihydromorphine, buprenophine or a salt of any of the foregoing and mixtures of any of the forgoing, and wherein the dosage form provides an in-vitro dissolution rate being substantially independent of pH and wherein the dosage form provides a peak plasma level of opioid in-vivo from 2 to 8 hours after administration of the dosage form and the dosage form is suitable for administration on a once-a-day basis.