Sublingual Methadone for the Management of Cancer-related Breakthrough Pain in Outpatients

Inclusion Criteria: * Pain due to cancer or its treatment; controlled baseline pain; * episodes of breakthrough pain every day that are "4/10" in severity or greater, ; * ast 10 minutes or longer, and * are responsive to short acting oral opioids such as morphine or hydromorphone; * are able to hole a volume of 1.0cc of water under the tongue for a 5-minute period; are able to provide written informed consent; * are able to fill out the study forms Exclusion Criteria: * Severe underlying respiratory disease such that an investigator is wary about the risk of respiratory failure from modest doses of opioid; * prior sensitivity to methadone; * currently are being administered methadone; * have breakthrough pain that in the opinion of the investigator is likely to change within the next seven days (recent or imminent radiation therapy to the main site of pain, * new chemotherapy or use of an injectable bisphosphonate likely to alter the pain, new use corticosteroids within the past week with a corresponding change in pain, or other interventions judged likely to alter pain); * are clinically unstable or have a life expectancy of less than one month making completion of the trial unlikely