Inclusion Criteria:

• 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 (ie, barrier method with spermicide, steroidal contraceptive [oral, transdermal, implanted, and injected contraceptives must be used in conjunction with the barrier method], or intrauterine device [IUD]) and agree to continued use of this method for the duration of the study.
• The patient has chronic pain of at least 3 months duration associated with any of the following conditions: cancer, diabetic peripheral neuropathy, postherpetic neuralgia, traumatic injury, complex regional pain syndrome, back pain, neck pain, fibromyalgia (patient has met diagnostic criteria), chronic pancreatitis, or osteoarthritis. Other chronic painful conditions may be evaluated for entry upon discussion with and written approval from the Cephalon medical expert.
• 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 a stable dose of ATC therapy for at least 7 days prior to enrollment in the study.
• The patient reports an average pain intensity score, over the prior 24 hours, of 6 or less (0=no pain through 10=worst pain)for the 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 3 hours.
• The patient currently uses opioid therapy for alleviation of BTP episodes occuring 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, and return to the clinic for scheduled study visits and a follow-up evaluation 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 known or suspected hypersensitivities, allergies, or other contraindications to any ingredient in the study drug.
• The patient has a recent history (within 5 years) or current evidence of alcohol or other substance abuse.
• The patient has cardiopulmonary disease that, in the opinion of the investigator, would 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's primary painful condition is headache, including migraine.
• The patient is expected to have surgery during the study, and it is anticipated that the surgery will alleviate the patient's pain.
• 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 fentanyl buccal tablets.
• The patient has participated in a study involving an investigational drug in the previous 30 days.
• 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, in the opinion of the investigator, would 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 chronic pain currently being treated.
• The patient has a positive urine drug screen (UDS) for an illicit substance or a medication not legitimately prescribed to the patient.