Study of D-Methadone in Patients With Chronic Pain

Inclusion Criteria:

Phase I and Phase II portions of the study:

18 years of age or older
Chronic pain with average 24 hour intensity rated at least 3 on a verbal numerical scale from 0-10 during the 24 hours prior to study entry.
Give informed consent to participate in this study.
Karnofsky Performance Score (KPS) >= to 80
Negative urine pregnancy test, verified by the study nurse, at study entry (for women of child-bearing potential). Patients must also use a medically approved contraceptive method during the study period.

Phase I only:

Responsible companion living with patient during study.

Phase II only:

Group 1 -- Patients must be taking chronic opioid therapy (long acting morphine, long acting oxycodone, transdermal fentanyl) at a stable dose for a minimum of four days. The dose of as needed short acting opioid does not need to be stable.
Group 2 -- Patients must not be receiving opioids and must have cancer related neuropathic pain secondary to post-chemotherapy peripheral neuropathy, post-radiation and/or post surgical plexopathy, radiculopathy or neuropathy, or post- herpetic neuralgia.

Exclusion Criteria:

Phase I and Phase II:

Known hypersensitivity to methadone
Patient taking methadone or with a history of methadone treatment within one month of study enrollment.

Patient that requires changes in the dose of one of the following medications within 2 weeks of study enrollment:

Abacavir,
Benzodiazepines,
Carbamazepine,
Efavirenz,
Fluconazole,
Fluvoxamine,
FOS amprenavir,
Fosphenytoin,
Naltrexone,
Nelfinavir,
Nevirapine,
Phenytoin,
Rifampin,
Rifapentine,
Risperidone,
Ritonavir,
St. John's Wort,
Zidovudine
Hepatic function tests (SGOT, alkaline phosphatase, bilirubin) greater than 2 times the upper limit of normal or creatinine greater than 1.4 within 30 days of study entry.
Neurologic or psychiatric disease sufficient, in the investigator's opinion, to compromise data collection.
Women who are pregnant or nursing.
Women of childbearing potential who do not agree to use a medically recognized method of contraception during the study period.