Our study aims at contributing to a valid appraisal of the magnitude of naltrexone efficacy as an antidissociative agent by using a double-blind randomized controlled trial.

Patients were randomized into two groups starting with either 3 weeks of 50 mg/d naltrexone or with 3 weeks of placebo. In either case the active treatment phases (weeks 1-6) were followed by one week of placebo. The major purpose of weeks 1-2 and 4-5, respectively, was to achieve a steady state during the active treatment. The primary comparisons of psychopathology under naltrexone and placebo refer to the weeks following the intended achievement of a steady state (weeks 3 and 6, respectively).

6 weeks of treatment were split into two phases: (A) 3 weeks of pharmacologically active treatment with naltrexone and (B) 3 weeks of pharmacologically inactive treatment with placebo (cross-over design). The sequence of the two treatment phases was randomized and concealed from both the patients and the health care professionals. In both cases, the last week ("Week 7") was without pharmacological intervention.

The primary outcome was based on the DSS, a reliable and valid self-rating instrument to assess dissociative experiences and inner tension during the last 24 hours (Stiglmayr et al. 2001) Mean scores for intensity (ranging from 0="no" to 9="very strong") and for duration (average time during which a particular symptom was present during the last 24 hours (in %)) were calculated for (a) dissociation (calculated from 21 Likert type items) and of (b) aversive inner tension (one item).

Inclusion Criteria:

• Diagnosis of BPD according to DSM-IV
• DES score ≥ 18
• Female gender
• Age between 18 and 50 years

Exclusion Criteria:

• Lifetime diagnosis of schizophrenia, psychotic or delusional disorder
• Current major depressive episode
• Lifetime diagnosis opioid dependence
• Current diagnosis opioid abuse
• Liver insufficiency or hepatitis
• Other major medical or neurological medical condition
• Pregnancy or lactation
• Psychotropic medication within two weeks before and during the trial (fluoxetine 4 weeks, lithium 8 weeks)
• Concomitant treatment with opioid analgetics
• Hypersensitivity to naltrexone