• Responders at Day 3 [ Time Frame: 3 days ] [ Designated as safety issue: No ]

  Responders included the number of participants who received the scheduled dose of Suboxone at the Day 3 study visit. Participants who discontinued the study at Day 3 were considered non-responders.

  All participants that continued the study received Suboxone tablets on Day 3.

  
  

• Illicit Opioid and Non-opioid Drug Use: Urine Drug Screen (UDS) [ Time Frame: 28 days ] [ Designated as safety issue: No ]
  Number of participants who tested negative on UDS during open-label phase on Day 28. The drugs screened on Day 28 included amphetamines, methamphetamines, cocaine, morphine, methadone, benzodiazepines, and tetrahydrocannabinol. Buprenorphine was only tested at screening and randomization according to protocol, therefore no values for buprenorphine are available for Day 28.
  
  
• Illicit Opioid and Non-opioid Drug Use: Substance Use Inventory (SUI) [ Time Frame: Days 3 to 28 ] [ Designated as safety issue: No ]
  Number of participants with intravenous use of drug as measured by self-reported SUI from Days 3-28. The SUI form consisted of questions addressing the number of days and times a drug was used, and the route of drug use. For suboxone the use of scheduled study medication was not considered illicit use.
  
  
• Self-reported Opioid Withdrawal Symptoms (SOWS) [ Time Frame: Baseline and 28 days ] [ Designated as safety issue: No ]
  SOWS were 16 items whose intensity was scored on a scale from 0 (not at all) to 4 (extremely) for a maximum possible score of 64. A total score of 0 represented the best outcome and a score of 64 represented the worst outcome. Participants were scored for SOWS at baseline (prior to randomization) and on Day 28. Reported are the scores for Day 28, and the change in scores from baseline to Day 28.
  
  
• Observer-rated Opioid Withdrawal Symptoms (OOWS) [ Time Frame: Baseline and 28 days ] [ Designated as safety issue: No ]
  The OOWS were 13 physically observable signs that were present (scored 1) or absent (scored 0). A total score of 0 represented the best outcome and a total score of 13 represented the worst outcome. Participants were scored for OOWS at baseline (prior to randomization) and on Day 28. Reported are the total score for Day 28, and the change in scores from baseline to Day 28.
  
  
• Addiction-related Severity Index (ASI-Lite): A Composite Score to Evaluate Seven Potential Problem Areas: Medical, Employment/Support Status, Alcohol, Drug, Legal, Family/Social, and Psychiatric [ Time Frame: Baseline and 28 days ] [ Designated as safety issue: No ]

  The ASI-Lite is a standardized, multidimensional, semi-structured, comprehensive interview that estimates addiction-related problem severity profiles in seven domains commonly affected in substance abusers. ASI-lite composite score ranges from 0 (worst outcome) to 1 (best outcome) for each category. Reported here is the change in ASI-Lite from baseline to Day 28.

  The original drug use accounts for heroin, methadone, other opiates, analgesics, medicine/pills, cocaine, amphetamines, cannabis, hallucinogens, and inhalants. Modified drug use accounts for heroin, methadone, cocaine, and cannabis.

  
  
• Compliance Rate [ Time Frame: 28 days ] [ Designated as safety issue: No ]
  Compliance rate was calculated as the number of days study medication was taken divided by the number of days study medication should have been taken X 100. The number of days study medication should have been taken was equal to the duration of treatment.
  
  
• Responders at Day 28 [ Time Frame: 28 days ] [ Designated as safety issue: No ]
  Responders were the number of participants in each group who received the scheduled 8- to 24-mg dose of Suboxone at study visit day. A participant who discontinued from the study was treated as a non-responder at the timepoint after the participant discontinued.
  
  

Rationale: Once Suboxone becomes available for widespread clinical use, it is anticipated that opioid-dependent patients seeking treatment with buprenorphine will be placed directly onto Suboxone. Two strategies that have had good success for inducting patients onto Suboxone have been developed: 1) a "bridging" procedure in which patients initiate therapy with Subutex and then transfer to Suboxone, and 2) a direct Suboxone induction procedure. However, there have been no controlled studies of direct Suboxone induction, and it is not clear whether using a Subutex-to-Suboxone induction procedure would produce any added clinical benefit for the patient relative to direct Suboxone induction.

This study addresses a post-marketing commitment to the European Medicines Agency to conduct a prospective, controlled study of induction with Suboxone. Using a prospective, randomized, active-drug-controlled, double-blind and double-dummy design, this study will assess the acceptability and safety of Suboxone in heroin users by comparing the clinical response of participants who are inducted directly onto Suboxone with that of participants who are inducted first to Subutex and then transferred to Suboxone. The dose regimen used during the induction phase of this study is identical to that used in the pivotal efficacy study comparing Suboxone and Subutex (Fudala et al, 2003), which is included in the Suboxone Summary of Product Characteristics. The data collected in this study will include information on the extent of opioid use before treatment initiation.

Two strategies for inducting opioid-dependent patients using short-acting opioids (eg, heroin) onto Suboxone have emerged from published US studies. One involves using Subutex to "bridge" the transition to Suboxone by using Subutex over the first 2 days before transferring directly to Suboxone on the third day. The other involves direct Suboxone induction, in which patients receive Suboxone as the initial dose followed by continued rapid Suboxone dose titration.

In the pivotal efficacy study, opiate-dependent heroin users assigned to either Subutex or Suboxone groups received an induction dose of 8 mg of Subutex (administered as a single 8-mg tablet) on Day 1 and 16 mg of Subutex (administered as two 8-mg tablets) on Day 2. The 109 participants assigned to Suboxone received 16 mg of Suboxone (administered as two 8-mg tablets) on Day 3, and the 105 participants assigned to Subutex received 16 mg of Subutex (administered as two 8-mg tablets) on Day 3. The induction schedule used in the pivotal trial, in which a Subutex-to-Suboxone bridging procedure was used, was successful for inducting heroin-dependent patients onto Suboxone, achieving good compliance and resulting in relatively few AEs accounting for treatment discontinuation.

Overall, several large-scale studies using Suboxone as an initial medication have been conducted with good results, and it appears clear that, as was the case in the pivotal study, most patients safely tolerate a total dose of at least 8 mg on the first day of treatment. However, as these studies were not controlled, it remains unclear whether using a Subutex-to-Suboxone induction procedure would produce any added clinical benefit to the patient relative to a direct Suboxone induction procedure. Furthermore, there have been no studies of direct Suboxone induction outside of the United States.