Inclusion Criteria:

• Buprenorphine/naloxone (BUP/NAL) users (taking 16/4 mg sublingually daily) for at least 3 weeks deemed by the investigator to have acceptable medical history, physical examination, 12 lead electrocardiogram, and clinical laboratory evaluations consistent with BUP maintenance will be eligible to participate in the study.
• Subjects who meet the criteria of opiate dependence, are enrolled in long-term BUP maintenance therapy, and have been on a stable dose of BUP/NAL for at least 3 weeks.
• Body weight > 60 kg for males and > 40 kg for females
• Body Mass Index (BMI) of 18 to 30 kg/m2, inclusive. BMI = weight (kg)/ [height(m)]2.
• Male or females, ages > 18 to < 60 years.
• Women of childbearing potential (WOCBP) must not be nursing or pregnant and must be on adequate non-hormonal contraception to avoid pregnancy. WOCBP must have a negative serum or urine pregnancy test (minimum sensitivity 25 IU/L or equivalent units of HCG) within 24 hours prior to the start of Study Day 1.

Exclusion Criteria:

• History or current evidence of any significant acute or chronic medical illness that, within the investigator's discretion, would interfere with the conduct or interpretation of the study.
• History of acute or chronic pancreatitis.
• History of uncontrolled chronic medical illness which could adversely affect the subject's adherence to study protocol or affect patient safety in the opinion of the investigator
• Use of any medication thought to significantly alter the metabolism of tipranavir, ritonavir, Buprenorphine or naloxone.
• History of any hemolytic disorders (including drug-induced hemolysis).
• Proven or suspected acute hepatitis at the time of study entry.
• Chronic liver disease with Childs-Pugh Class B or C staging
• Current or recent (within 3 months) gastrointestinal disease which would interfere with the conduct or interpretation of the study.
• Any major surgery within 4 weeks of enrollment. Minor surgical procedures requiring local anesthesia are exceptions.
• Any gastrointestinal surgery that could impact upon the absorption of study drug.
• Donation of blood or plasma to a blood bank or in a clinical study (except a screening visit) within 4 weeks of enrollment.
• Blood transfusion within 4 weeks of enrollment.
• Inability to tolerate oral medication.
• Inability to tolerate venipuncture and/or absence of secure venous access.
• Inability to refrain from smoking during in-residence period
• Known or suspected HIV infection (subjects who are found to be positive upon screen for HIV will be excluded).
• Known active drug or alcohol abuse, which in the opinion of the investigator makes study participation to completion unlikely.
• Any other sound medical, psychiatric and/or social reason as determined by the Investigator.
• Evidence of organ dysfunction or any clinically relevant (as determined by the investigator) deviations from the norms observed in a buprenorphine/naloxone treated population in physical examination, vital signs, ECG or clinical laboratory determinations.
• Ingestion of alcohol within 24 hours prior to the dose of study medication
• Positive breathalyzer alcohol test, or positive urine screen for barbiturates, benzo-diazepines, amphetamines, THC, cocaine or opiates other than buprenorphine/naloxone.
• Positive blood screen for HIV antibody.
• Subjects with AST, ALT or bilirubin > 2.5X the upper limit of normal.
• Hemoglobin < 9 g/dL, and platelet count < 75, 000/mm3.
• Positive serum or urine for HCG.
• History of any significant drug allergy, drug rash or sensitivity to any class of drugs relevant to the study drugs.