This study is designed to determine if opioid dependent subjects who are already receiving Subutex and/or Suboxone can transfer to RBP-6300. Upon completing the study, subjects will continue their pre-study prescribed dosage of Subutex and/or Suboxone

During the open-label Run-In Period (study days -7 to -1), participants receive Subutex®/Suboxone® at one of three dose levels, depending on the dose level for that subject on entry to the study: 8 mg/day, 16 mg/day, or 24 mg/day.

During the 7-day, active drug-controlled, double-blind Transfer Period (study days 1-7), participants are randomized to either Subutex®/Suboxone® or RBP-6300 active drug at dosing levels equivalent to the level during the Run-In Period plus placebo matching the other drug.

This is followed by a 3-day single-blind Subutex®/Suboxone® Transition Period in which participants receive the same dose given during the Run-In Period.

Inclusion Criteria:

• Be Male or non-pregnant, non-lactating females
• Be at least 18 years of age
• Meet Diagnostic and Statistical Manual of Mental Disorders, DSM-IV-TR (Diagnostic and Statistical Manual-IV-TEXT REVISION)criteria for opioid dependence at screening
• Be on stable dose of 8, 16, or 24mg/day for about 30 days prior to screening
• Female subjects of childbearing potential must have a negative urine test prior to enrollment into the study

Exclusion Criteria:

• Have participated in an experimental drug or device study within the last 60 days
• If female, be breast feeding or lactating
• Have any medical condition that in the opinion of the physician investigator would preclude the subject from completing the study
• Have a clinically significant abnormal finding (in the opinion of the investigator)