Patients are treated with 24-hour oral sustained release opioid formulations which, upon administration, provide an initially rapid opioid absorption such that the minimum effective analgesic concentration of the opioid is more quickly achieved. These sustained release opioid formulations include an effective amount of at least one retardant material to cause said opioid analgesic to be released at a such a rate as to provide an analgesic effect after oral administration to a human patient for at least about 24 hours, and are characterized by providing an absorption half-life from 1 to about 8 hours. A method of titrating a human patient utilizing these sustained release opioid formulations is also disclosed.