Pharmacokinetics and pharmacodynamics of multiple sublingual buprenorphine tablets in dose-escalation trials.

In this investigation, the pharmacokinetic and pharmacodynamic properties were determined of multiple doses of sublingual tablets containing either buprenorphine alone or buprenorphine and naloxone. Subjects were experienced opiate users who received escalating doses (4-24 mg) of buprenorphine either alone or in combination with naloxone. Peak concentration (Cmax) and area under the concentration-time curves (AUCs) increased for both buprenorphine and naloxone with escalating doses. Significant differences were found across the range of doses administered for dose-adjusted Cmax for both tablet formulations and for the dose-adjusted AUCs for the buprenorphine-naloxone tablets. For both formulations, the maximal buprenorphine-induced decreases in respiratory rate and pupil diameter did not vary significantly across doses. Several of the subjective effects of buprenorphine did not increase as the dose of buprenorphine administered was increased. These findings are consistent with the ceiling effect associated with the partial agonist actions of buprenorphine. They also indicate a lack of dose proportionality for buprenorphine sublingual tablets, at least during the times at which levels of this agent are highest.

Nefazodone treatment of cocaine dependence with comorbid depressive symptoms.

AIMS: In the current study, nefazodone, an antidepressant with dual action on serotonin and norepinephrine reuptake as well as 5-HT(2A) receptor antagonist effects, was studied in subjects with cocaine dependence and depressive symptoms, to determine its efficacy in reducing cocaine use. DESIGN: An 8-week, double blind, placebo-controlled design was used. SETTING: The study was conducted at the Medication Development Research Unit (MDRU) at the VA Boston Healthcare System and the Manhattan Department of Veterans Affairs (DVA) Medical Center. PARTICIPANTS: Subjects (n = 69) met Diagnostic and Statistical Manual version IV (DSM-IV) criteria for cocaine dependence and had Hamilton Depression Scores of 12 or higher. INTERVENTION: Subjects were assigned randomly to receive nefazodone 200 mg twice daily (n = 34) or matching placebo (n = 35). All subjects received individual counseling. MEASUREMENTS: Urinary measurements of benzoylecgonine (BE, three times per week) and self-reports of cocaine use were the primary outcome measures. Secondary outcome measures included assessments of psychiatric functioning, cocaine craving and social functioning. FINDINGS: Median weekly BE declined more rapidly in the nefazodone than in the placebo group. Median urine BE at baseline was, however, significantly greater in nefazodone than in the placebo group. Scores for strength of cocaine craving also decreased more rapidly in the nefazodone group compared to the placebo group. Both groups had equivalent improvement in mood, psychosocial functioning and self-reported cocaine use. CONCLUSIONS: These results suggest that nefazodone administration can reduce cocaine craving after it has been administered for several weeks. Although the nefazodone group had a greater rate of decrease in BE levels than the placebo group, the interpretation of this finding is obscured by significant group differences in baseline BE levels.

Efficacy screening trials of paroxetine, pentoxifylline, riluzole, pramipexole and venlafaxine in cocaine dependence.

AIMS: The two studies presented here were conducted to assess the efficacy of paroxetine, pentoxifylline, riluzole, venlafaxine and pramipexole as medications for the treatment of cocaine dependence. DESIGN: A multi-arm, modified blinded, placebo-controlled design was used. SETTING: The studies were conducted at the Boston VA Healthcare System and the Boston University School of Medicine Medication Development Research Unit (MDRU). PARTICIPANTS: Participants met criteria for cocaine dependence during a 2-week screening period. INTERVENTION: Following random assignment to one of the treatment groups, subjects received active medication or placebo for 8 weeks in combination with cognitive behavioral counseling. In the first study the efficacy of the antidepressant paroxetine (20 mg daily), the phosphodiesterase inhibitor pentoxifylline (1200 mg daily) and the glutamate release inhibitor riluzole (100 mg daily) was assessed. The antidepressant venlafaxine (150 mg daily) and the dopamine agonist pramipexole (1.5 mg daily) were evaluated in the second study. MEASUREMENTS: Urine benzoylecgonine (BE) concentrations, self-report of cocaine use and global impression scores served as primary outcome measures. Secondary measures included assessments of cocaine craving and psychiatric functioning. Adverse events were monitored during the treatment period. FINDINGS: None of the active medications produced greater reductions in urine BE concentrations over the treatment period than did placebo. There were trends for BE levels to become reduced in the pentoxifylline group during the first 4 weeks of treatment and for Addiction Severity Index (ASI) drug composite scores to be lower in the pentoxyfylline group at end-point compared to the placebo group. Significant within-group reductions in reported cocaine use and craving were found for all treatment groups, but none of the active medications were superior to placebo on these measures. The accuracy of self-reported cocaine use declined over the study period. Overall, the active medications were well tolerated. CONCLUSIONS: This study does not support the use of paroxetine, pentoxifylline, riluzole, venlafaxine or pramipexole for the treatment of cocaine dependence. However, these results need to be interpreted with caution because of the small size and lack of homogeneity of the experimental groups.