This is a single site, double-blind, randomized, placebo-controlled, crossover study to assess the pharmacodynamics (PD) of RDC-0313 coadministered with buprenorphine in 12 healthy, opioid-experienced, non-treatment-seeking subjects.

Inclusion Criteria:

• Subject must be capable of understanding and complying with the protocol and has signed the informed consent
• Must be 18-55 years of age
• Must have a body mass index of 18.0-30.0 kg/m2 at screening
• Female subjects must agree to use an acceptable method of contraception from date of consent and until two weeks after the last dose
• Subjects must be willing not to use alcohol-, tobacco, caffeine-, or xanthine-containing products while resident at inpatient facility
• Subjects must be an experienced opioid user who meets the following criteria: 1) has used opioids for non-therapeutic purposes (ie, for psychoactive effects) on at least 10 occasions in the past five years; 2) has used opioids at least 2 times in the two years prior to screening; and 3) is not physically dependent on opioids, as assessed by medical history and naloxone challenge performed at screening

Exclusion Criteria:

• Must not have any current or piror significant hepatic, renal, endocrine, cardiac, nervous, psychiatric, gastrointestinal, pulmonary, hematologic, or metabolic disorders.
• Must not have current or past opioid, alcohol, or other durg dependence (excluding nicotine and caffeine) or showing signs of withdrawal following the naloxone (Narcan) challenge.
• Please contact site for additional information about other exclusion criteria.