Evaluate the efficacy of treatment with Fentanyl Buccal Tablets (FBT) compared with immediate release oxycodone in alleviating breakthrough pain in opioid tolerant patients with chronic pain.

Inclusion Criteria:

• The patient has chronic pain of at least 3 months duration associated with: diabetic peripheral neuropathy, postherpetic neuralgia, traumatic injury, complex regional pain syndrome, back pain, neck pain,fibromyalgia, chronic pancreatitis, osteoarthritis,or cancer.
• The patient is currently using 1 of the following: at least 60 mg of oral morphine/day, or at least 25 mcg of transdermal fentanyl/hour, or at least 30 mg of oxycodone/day, or at least 8 mg of hydromorphone/day, or an equianalgesic dose of another opioid/day as ATC therapy for at least 7 days before administration of the first dose of study drug
• The patient is willing to provide written informed consent to participate in this study.
• The patient is 18 through 80 years of age.
• Women must be surgically sterile, 2 years postmenopausal, or, if of childbearing potential, using a medically accepted method of birth control and agree to continued use of this method for the duration of the study.
• Any patient with cancer should have a life expectancy of at least 3 months.
• The patient reports an average PI score, over the prior 24 hours, of 6 or less (0=no pain through 10=pain as bad as you can imagine) for their chronic pain.
• The patient experiences, on average, 1 to 4 BTP episodes per day while taking ATC opioid therapy, and on average, the duration of each BTP episode is less than 4 hours.
• The patient currently uses opioid therapy for alleviation of BTP episodes, occurring at the location of the chronic pain, and achieves at least partial relief.
• The patient must be willing and able to successfully self-administer the study drug,comply with study restrictions, complete the electronic diary, and return to the clinic for scheduled study visits as specified in this protocol.

Exclusion Criteria:

• The patient has uncontrolled or rapidly escalating pain as determined by the investigator (ie, the ATC therapy may be expected to change between the first and last treatments with study drug), or has pain uncontrolled by therapy that could adversely impact the safety of the patient or that could be compromised by treatment with study drug.
• The patient has a recent history (within 5 years) or current evidence of alcohol or other substance abuse.
• The patient has known or suspected hypersensitivities, allergies, or other contraindications to any ingredient in either study drug.
• The patient has cardiopulmonary disease that would, in the opinion of the investigator, significantly increase the risk of treatment with potent synthetic opioids.
• The patient has medical or psychiatric disease that, in the opinion of the investigator, would compromise collected data.
• The patient is expected to have surgery during the study that will impact the patient's chronic pain and/or BTP.
• The patient has had therapy before study drug treatment that, in the opinion of the investigator, could alter pain or response to pain medication.
• The patient is pregnant or lactating.
• The patient has participated in a previous study with FBT.
• The patient has participated in a study involving an investigational drug in the prior 30 days.
• The patient is currently using prescription FBT or immediate-release oxycodone for BTP and is unwilling to undergo re-titration.
• The patient has received a monoamine oxidase inhibitor (MAOI) within 14 days before the first treatment with study drug.
• The patient has any other medical condition or is receiving concomitant medication/therapy (eg, regional nerve block) that could, in the opinion of the investigator, compromise the patient's safety or compliance with the study protocol,or compromise collected data.
• The patient is involved in active litigation in regard to the chronic pain currently being treated.
• The patient has a positive UDS for an illicit drug or a medication not prescribed for him/her or which is not medically explainable.