Pharmacodynamics must inform statistics: an example from a cocaine dependence pharmacotherapy trial.

Background. There is no FDA-approved medication for cocaine dependence or consensus on the statistical approach for analyzing data from cocaine dependence pharmacotherapy trials. The goal of this paper is to illustrate the importance of understanding medication's pharmacodynamics when specifying the statistical model to test its efficacy. Method. Data from a double-blind placebo controlled trial of reserpine for cocaine dependence are analyzed. Since the antihypertensive properties of reserpine are well established, blood pressure data are utilized to evaluate the ability of two statistical models, one that does not take the pharmacodynamics of reserpine into account and one that does, to detect reserpine's antihypertensive effect. Results. The statistical model specified without regard to reserpine's pharmacodynamics failed to find a significant medication effect for either systolic (P = 0.49) or diastolic (P = 0.59) blood pressure. Contrariwise, the model based on the pharmacodynamics of reserpine found a significant effect for both systolic (P = 0.002) and diastolic (P = 0.004) blood pressure. Conclusions. If the pharmacodynamics of a study medication are not considered when specifying statistical models, then erroneous conclusions may be reached. This trial is registered with NCT00033033.

An Evaluation of Substance Abuse Treatment and HIV Education on Safe Sex Practices in Cocaine Dependent Individuals.

Background. There is a strong association between crack/cocaine use and increased sexual risk behavior, but little research on the efficacy of HIV education for decreasing such behavior in crack/cocaine-addicted individuals in substance abuse treatment. Method. Datasets from two cocaine dependence trials including either one or three HIV education sessions, respectively, were analyzed for changes over time in the proportion of participants practicing safe sex. A pooled dataset from two earlier trials not offering HIV education was also analyzed. Results. We included 83 participants from the 1-session trial and 65 participants from the 3-session trial. Both sets of participants evidenced a significant increase in the proportion of participants having safe sex with casual partners. Participants in the 3-session HIV education study also evidenced a significant increase in the proportion of participants having safe sex with regular partners. In the trials without HIV education, no change in safe sex practices was found, and change in condom use was observed only among female participants. Conclusions. These findings are consistent with recommendations that HIV education/counseling should be provided to individuals in substance abuse treatment. A randomized controlled trial to confirm these results may be warranted. This trial is registered with NCT00033033, NCT00086255, NCT00015106, and NCT00015132.

Treating nicotine dependence by targeting attention-deficit/ hyperactivity disorder (ADHD) with OROS methylphenidate: the role of baseline ADHD severity and treatment response.

OBJECTIVE: To determine whether treatment of attention-deficit/hyperactivity disorder (ADHD) with osmotic-release oral system (OROS) methylphenidate promotes abstinence from smoking among smokers with ADHD who have greater severity of ADHD symptoms at baseline or greater improvement in ADHD during treatment. METHOD: This is a secondary analysis of data from a randomized, double-blind, 11-week trial conducted between December 2005 and January 2008 at 6 clinical sites; the original trial was sponsored by the National Drug Abuse Clinical Trials Network. Adult cigarette smokers (aged 18-55 years) who met DSM-IV criteria for ADHD were randomly assigned to OROS methylphenidate (72 mg/d) (n = 127) or matching placebo (n = 128). All participants received nicotine patches (21 mg/d) and weekly individual smoking cessation counseling. Logistic regression was used to model prolonged abstinence from smoking (ascertained by self-report and breath carbon monoxide testing) as a function of treatment, baseline ADHD Rating Scale-IV (ADHD-RS) score, change in ADHD-RS score during treatment, and their interactions. RESULTS: Treatment interacted with both ADHD-RS score at baseline (P = .01) and change in ADHD-RS score during treatment (P = .008). Among patients with higher ADHD-RS scores (> 36) at baseline and the most improvement in ADHD during treatment (ADHD-RS change score ≥ 24), 70.0% of those who took OROS methylphenidate achieved abstinence from smoking compared to 36.8% of those who took placebo (P = .02). In contrast, among patients with the lowest ADHD-RS baseline scores (≤ 30), 30.3% of those who took OROS methylphenidate achieved abstinence from smoking compared to 60.7% of those who took placebo (P = .02). CONCLUSIONS: OROS methylphenidate, in combination with nicotine patch, may be an effective treatment for nicotine dependence among smokers with more severe ADHD and more robust response of ADHD symptoms to medication. OROS methylphenidate may be counterproductive among smokers with lower severity of ADHD. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00253747.

A multisite, double-blind, placebo-controlled clinical trial to evaluate the safety and efficacy of vigabatrin for treating cocaine dependence.

IMPORTANCE: Cocaine dependence is a significant public health problem, yet no validated pharmacological treatment exists. The potent γ-aminobutyric acid (GABA)ergic medication vigabatrin has previously been shown to be effective in a double-blind single-site study conducted in Mexico. OBJECTIVE: To evaluate the safety and efficacy of vigabatrin for the treatment of cocaine dependence in a U.S. sample. DESIGN AND SETTING: Multisite, randomized, double-blind, placebo-controlled, 12-week clinical trial with follow-up visits at weeks 13, 16, 20, and 24 in 11 U.S. sites. PARTICIPANTS: In total, 186 treatment-seeking participants with cocaine dependence (mean age, 45 years). Approximately 67% were male, and about 60% were of African American race/ethnicity. INTERVENTIONS: Participants received twice-daily doses of vigabatrin (total dosage, 3.0 g/d) or matched placebo, plus weekly computerized cognitive behavioral therapy and biweekly individual counseling for 13 weeks. Contingency management encouraged the provision of urine samples. MAIN OUTCOMES AND MEASURES: The primary outcome measure was the proportion of participants with cocaine abstinence during the last 2 weeks of the 12-week treatment phase as assessed by self-reports and quantitative urine drug screens. The weekly fraction of cocaine use days and the number of drug-free urine samples during weeks 1 through 13 were key secondary measures. RESULTS: No significant differences were observed between the vigabatrin group and the placebo group on the primary outcome measure (P = .67), key secondary measures (P > .99), or other outcome measures. However, while pill counts and self-reports indicated that more than 66% of all participants (and >63% of the vigabatrin group) took more than 70% of their medication, post hoc vigabatrin urine concentration levels suggested that approximately 40% to 60% of patients taking vigabatrin may not have been adherent. This lack of adherence may have obscured any evidence of vigabatrin efficacy. No visual acuity or visual field deterioration occurred in any of the participants. CONCLUSIONS AND RELEVANCE: No protocol-defined differences in efficacy between vigabatrin treatment and placebo were detected for any outcome variable. This may have been due to medication nonadherence or, alternatively, due to the weak efficacy of vigabatrin. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00611130.

Frontal systems deficits in stimulant-dependent patients: evidence of pre-illness dysfunction and relationship to treatment response.

BACKGROUND: Frontal systems dysfunction is present in stimulant-dependent patients. However, it is unclear whether this dysfunction is a pre-morbid risk factor or stimulant-induced, is severe enough to be clinically relevant, and if it is relevant to treatment response. These questions were addressed using the Frontal Systems Behavior Scale (FrSBe), a reliable and valid self-report assessment of three neurobehavioral domains associated with frontal systems functioning (Apathy, Disinhibition, and Executive Dysfunction, summed for a Total), that assesses both pre- and post-morbid functioning, and has a specific cutoff for defining clinically significant abnormalities. METHOD: Six sites evaluating 12-step facilitation for stimulant abusers obtained the FrSBe from 180 methamphetamine- and/or cocaine-dependent participants. Dichotomous treatment response measures included self-reported stimulant use, stimulant urine drug screens, and treatment completion. RESULTS: A substantial percentage of participants retrospectively reported clinically significant neurobehavioral abnormalities prior to lifetime stimulant abuse initiation (e.g., 67.5% on FrSBe-Total) with a significant increase in the proportion reporting such abnormalities for current functioning (86% on FrSBe-Total; p<0.0001). Treatment response was significantly worse for participants with, relative to those without, clinically significant Disinhibition as measured by treatment non-completion (31.6% vs. 15.6%, OR=2.51) and self-reported stimulant use during treatment (40.5% vs. 16.7%, OR=3.40). CONCLUSION: These findings suggest that frontal systems dysfunction is present prior to stimulant-abuse onset and worsens with stimulant use. Disinhibition may be a prime target for intervention in stimulant-dependent individuals.

Primary outcome indices in illicit drug dependence treatment research: systematic approach to selection and measurement of drug use end-points in clinical trials.

AIMS: Clinical trials test the safety and efficacy of behavioral and pharmacological interventions in drug-dependent individuals. However, there is no consensus about the most appropriate outcome(s) to consider in determining treatment efficacy or on the most appropriate methods for assessing selected outcome(s). We summarize the discussion and recommendations of treatment and research experts, convened by the US National Institute on Drug Abuse, to select appropriate primary outcomes for drug dependence treatment clinical trials, and in particular the feasibility of selecting a common outcome to be included in all or most trials. METHODS: A brief history of outcomes employed in prior drug dependence treatment research, incorporating perspectives from tobacco and alcohol research, is included. The relative merits and limitations of focusing on drug-taking behavior, as measured by self-report and qualitative or quantitative biological markers, are evaluated. RESULTS: Drug-taking behavior, measured ideally by a combination of self-report and biological indicators, is seen as the most appropriate proximal primary outcome in drug dependence treatment clinical trials. CONCLUSIONS: We conclude that the most appropriate outcome will vary as a function of salient variables inherent in the clinical trial, such as the type of intervention, its target, treatment goals (e.g. abstinence or reduction of use) and the perspective being taken (e.g. researcher, clinical program, patient, society). It is recommended that a decision process, based on such trial variables, be developed to guide the selection of primary and secondary outcomes as well as the methods to assess them.

Subjective effects, misuse, and adverse effects of osmotic-release methylphenidate treatment in adolescent substance abusers with attention-deficit/hyperactivity disorder.

OBJECTIVE: Psychostimulants are effective treatments for attention-deficit/hyperactivity disorder (ADHD) but may be associated with euphoric effects, misuse/diversion, and adverse effects. These risks are perceived by some clinicians to be greater in substance-abusing adolescents relative to non-substance-abusing adults. The present study evaluates the subjective effects, misuse/diversion, and adverse effects associated with the use of osmotic-release oral system methylphenidate (OROS-MPH), relative to placebo, for treating ADHD in adolescents with a substance use disorder (SUD) as a function of substance use severity and compared these risks with those associated with the treatment of ADHD in adults without a non-nicotine SUD. METHOD: Datasets from two randomized placebo-controlled trials of OROS-MPH for treating ADHD, one conducted with 303 adolescents (13-18) with at least one non-nicotine SUD and one with 255 adult smokers (18-55), were analyzed. Outcome measures included the Massachusetts General Hospital Liking Scale, self-reported medication compliance, pill counts, and adverse events (AEs). RESULTS: Euphoric effects and misuse/diversion of OROS-MPH were not significantly affected by substance use severity. The euphoric effects of OROS-MPH did not significantly differ between the adolescent and adult samples. Adults rated OROS-MPH as more effective in treating ADHD, whereas adolescents reported feeling more depressed when taking OROS-MPH. The adolescents lost more pills relative to the adults regardless of treatment condition, which suggests the importance of careful medication monitoring. Higher baseline use of alcohol and cannabis was associated with an increased risk of experiencing a treatment-related AE in OROS-MPH, but baseline use did not increase the risk of serious AEs or of any particular category of AE and the adolescents did not experience more treatment-related AEs relative to the adults. CONCLUSIONS: With good monitoring, and in the context of substance abuse treatment, OROS-MPH can be safely used in adolescents with an SUD despite non-abstinence.

Adjunctive counseling during brief and extended buprenorphine-naloxone treatment for prescription opioid dependence: a 2-phase randomized controlled trial.

CONTEXT: No randomized trials have examined treatments for prescription opioid dependence, despite its increasing prevalence. OBJECTIVE: To evaluate the efficacy of brief and extended buprenorphine hydrochloride-naloxone hydrochloride treatment, with different counseling intensities, for patients dependent on prescription opioids. DESIGN: Multisite, randomized clinical trial using a 2-phase adaptive treatment research design. Brief treatment (phase 1) included 2-week buprenorphine-naloxone stabilization, 2-week taper, and 8-week postmedication follow-up. Patients with successful opioid use outcomes exited the study; unsuccessful patients entered phase 2: extended (12-week) buprenorphine-naloxone treatment, 4-week taper, and 8-week postmedication follow-up. SETTING: Ten US sites. Patients A total of 653 treatment-seeking outpatients dependent on prescription opioids. INTERVENTIONS: In both phases, patients were randomized to standard medical management (SMM) or SMM plus opioid dependence counseling; all received buprenorphine-naloxone. MAIN OUTCOME MEASURES: Predefined "successful outcome" in each phase: composite measures indicating minimal or no opioid use based on urine test-confirmed self-reports. RESULTS: During phase 1, only 6.6% (43 of 653) of patients had successful outcomes, with no difference between SMM and SMM plus opioid dependence counseling. In contrast, 49.2% (177 of 360) attained successful outcomes in phase 2 during extended buprenorphine-naloxone treatment (week 12), with no difference between counseling conditions. Success rates 8 weeks after completing the buprenorphine-naloxone taper (phase 2, week 24) dropped to 8.6% (31 of 360), again with no counseling difference. In secondary analyses, successful phase 2 outcomes were more common while taking buprenorphine-naloxone than 8 weeks after taper (49.2% [177 of 360] vs 8.6% [31 of 360], P < .001). Chronic pain did not affect opioid use outcomes; a history of ever using heroin was associated with lower phase 2 success rates while taking buprenorphine-naloxone. CONCLUSIONS: Prescription opioid-dependent patients are most likely to reduce opioid use during buprenorphine-naloxone treatment; if tapered off buprenorphine-naloxone, even after 12 weeks of treatment, the likelihood of an unsuccessful outcome is high, even in patients receiving counseling in addition to SMM.

Impact of attention-deficit/hyperactivity disorder (ADHD) treatment on smoking cessation intervention in ADHD smokers: a randomized, double-blind, placebo-controlled trial.

OBJECTIVE: High smoking rates in adults with attention-deficit/hyperactivity disorder (ADHD) and nicotine's amelioration of ADHD suggest that effective ADHD treatment might facilitate abstinence in smokers with ADHD. The present study evaluated if using osmotic-release oral system methylphenidate (OROS-MPH) to treat ADHD enhances response to smoking cessation treatment in smokers with ADHD. METHOD: A randomized, double-blind, placebo-controlled, 11-week trial with a 1-month follow-up was conducted at 6 clinical sites between December 2005 and January 2008. Adults (aged 18-55 years) meeting DSM-IV criteria for ADHD and interested in quitting smoking were randomly assigned to OROS-MPH titrated to 72 mg/d (n = 127) or placebo (n = 128). All participants received brief weekly individual smoking cessation counseling for 11 weeks and 21 mg/d nicotine patches starting on the smoking quit day (day 27) through study week 11. Outcome measures included prolonged smoking abstinence and DSM-IV ADHD Rating Scale (ADHD-RS) score. RESULTS: Of 255 randomly assigned participants, 204 (80%) completed the trial. Prolonged abstinence rates, 43.3% and 42.2%, for the OROS-MPH and placebo groups, respectively, did not differ significantly (OR = 1.1; 95% CI, 0.63-1.79; P = .81). Relative to placebo, OROS-MPH evidenced a greater reduction in DSM-IV ADHD-RS score (P < .0001) and in cigarettes per day during the post-quit phase (P = .016). Relative to placebo, OROS-MPH increased blood pressure and heart rate to a statistically, but not clinically, significant degree (P < .05); medication discontinuation did not differ significantly between treatments. CONCLUSIONS: Treatment for ADHD did not improve smoking cessation success; OROS-MPH, relative to placebo, effectively treated ADHD and was safe and generally well tolerated in this healthy sample of adult ADHD smokers. TRIAL REGISTRATION: clinical trials.gov Identifier: NCT00253747.

A medication screening trial evaluation of reserpine, gabapentin and lamotrigine pharmacotherapy of cocaine dependence.

AIMS: To conduct a preliminary evaluation of the safety and efficacy of reserpine, gabapentin or lamotrigine versus an unmatched placebo control as a treatment for cocaine dependence. DESIGN: A 10-week out-patient study using the Cocaine Rapid Efficacy and Safety Trial (CREST) study design. SETTING: The study was conducted at the Cincinnati Medication Development Research Unit (MDRU). PARTICIPANTS: Participants met Diagnostic and Statistical Manual version IV (DSM-IV) criteria for cocaine dependence. Sixty participants were enrolled, with 50 participants completing the final study measures. INTERVENTION: The targeted daily doses of medication were reserpine 0.5 mg, gabapentin 1800 mg and lamotrigine 150 mg. All participants received 1 hour of manualized individual cognitive behavioral therapy on a weekly basis. MEASUREMENTS: Primary outcome measures of efficacy included urine benzoylecgonine (BE) level, Cocaine Clinical Global Impression scale--observer and self-report of cocaine use. Safety measures included adverse events, electrocardiograms (ECGs), vital signs and laboratory tests. FINDINGS: Subjective measures of cocaine dependence indicated significant improvement for all study groups. Urine BE results indicated a significant improvement for the reserpine group (P < 0.05) and non-significant changes for the other study groups. No pattern of physical or laboratory abnormalities attributable to treatment with any of the medications was identified. There were three serious adverse events reported, none of which were related to study procedures. The medications appeared to be tolerated well. CONCLUSIONS: The present findings suggest that reserpine may be worthy of further study as a cocaine dependence treatment.

A placebo-controlled screening trial of tiagabine, sertraline and donepezil as cocaine dependence treatments.

AIMS: To conduct a preliminary evaluation of the safety and efficacy of tiagabine, sertraline or donepezil versus an unmatched placebo control as a treatment for cocaine dependence. DESIGN: A 10-week out-patient study was conducted using the Cocaine Rapid Efficacy and Safety Trial (CREST) study design. SETTING: This study was conducted at the Cincinnati Medication Development Research Unit (MDRU) and at an affiliated site in Dayton, Ohio. PARTICIPANTS: Participants met Diagnostic and Statistical Manual version IV (DSM-IV) criteria for cocaine dependence. Sixty-seven participants were enrolled with 55 completing final study measures. INTERVENTION: The targeted daily doses of medication were tiagabine 20 mg, sertraline 100 mg and donepezil 10 mg. All participants received 1 hour of manualized individual cognitive behavioral therapy on a weekly basis. MEASUREMENTS: Primary outcome measures of efficacy included urine benzoylecgonine (BE) level, Cocaine Clinical Global Impression Scale-Observer and self-report of cocaine use. Safety measures included adverse events, ECGs, vital signs and laboratory tests. FINDINGS: Subjective measures of cocaine dependence indicated significant improvement for all study groups. Generalized estimating equations analysis indicated that the tiagabine group showed a trend toward a significant decrease in urine BE level from baseline to weeks 5-8 (P = 0.10) and non-significant changes for the other study groups. No pattern of physical or laboratory abnormalities attributable to treatment with any of the medications was identified. There were three serious adverse events reported, none of which were related to study procedures. CONCLUSIONS: The present findings suggest that tiagabine may be worthy of further study as a cocaine dependence treatment.

Cocaine Rapid Efficacy Screening Trials (CREST): lessons learned.

AIMS: The Cocaine Rapid Efficacy Screening Trials (CREST) were designed by the National Institute on Drug Abuse Division of Treatment Research and Development (NIDA, DT R&D) to rapidly screen a number of medications potentially useful for the treatment of cocaine dependence. DESIGN: Each CREST trial was designed to compare several medications in a single trial against an unmatched placebo. The placebo group was included in each trial to avoid the nearly universal positive response to medications seen in open-label trials. In addition, a common set of procedures and outcome measures were employed throughout to increase comparability of results obtained from different trials and from different times. PARTICIPANTS: In all, 18 medications were screened in seven different trials, conducted in four different sites throughout the United States involving 398 cocaine-dependent patients. FINDINGS: Three medications were found to be promising enough to include in subsequent larger trials. Common statistical procedures for evaluating medications were developed to facilitate comparisons across sites and across time. A portion of the data were pooled and analyzed, which yielded some useful insights into cocaine dependence and its treatment. Finally, a review of individual trials together with the pooled analysis revealed several potential improvements for future screening trials. CONCLUSIONS: Overall, the CREST trials proved to be useful for rapidly screening medications for treatment of cocaine dependence, but several modifications in design should be made before this framework is applied further.

An open-label pilot study of methylphenidate in the treatment of cocaine dependent patients with adult attention deficit/hyperactivity disorder.

A multi-site, open-label study of methylphenidate for treating patients with comorbid diagnoses of attention deficit/hyperactivity disorder and cocaine dependence was performed. Forty-one participants, who met DSM-IV criteria for adult attention deficit/hyperactivity disorder and cocaine dependence, were enrolled into this ten week outpatient study. The targeted total daily dose of methylphenidate was 60 mg (20 mg TID). Participants received individual substance abuse therapy throughout the trial. Safety measures included adverse events, vital signs, and electrocardiograms. Methylphenidate's efficacy was assessed by both objective and subjective measures. Seventy percent of the participants completed final study measures. Safety measures indicated that methylphenidate was well tolerated by the participants. Subjective efficacy measures suggested that participants evidenced improvement in both cocaine dependence and adult attention deficit/hyperactivity disorder symptoms. Quantitative benzoylecgonine indicated that only those participants categorized as being compliant showed improvement. A double-blind, placebo-controlled study of methylphenidate for this population may be warranted.

Measuring outcome in cocaine clinical trials: a comparison of sweat patches with urine toxicology and participant self-report.

AIMS: To evaluate the advantages of using a sweat patch (PharmCheck) for detecting cocaine abuse in cocaine-dependent patients participating in a clinical trial. The utility of the sweat patch was assessed from the following perspectives: the reliability and validity of quantitative sweat patch results, the possible degradation of cocaine to benzoylecgonine (BE) as a function of the length of time that a patch is worn, the completeness of the dataset yielded by thrice-weekly urine toxicology compared with thrice-weekly and weekly sweat patches, and the relative costs associated with sweat patch versus urine measures. DESIGN: Data were collected during a 10-week out-patient clinical trial in which participants wore two sweat patches, one applied every visit and one applied weekly. Urine samples were collected thrice weekly, as were self-reports of substance use. SETTING: A multi-site clinical trial conducted in Boston, Cincinnati and New York, USA. PARTICIPANTS: Twenty-seven participants with comorbid diagnoses of cocaine dependence and adult attention deficit disorder completed the study. MEASUREMENTS: Sweat patch and urine samples were analyzed by standard methods for cocaine and cocaine metabolites. FINDINGS: Quantitative sweat patch measures had good reliability in that the correlation between the weekly and per-visit patches was 0.96 (P < 0.0001). The concurrent validity, as judged by the correlation between quantitative urine BE levels and either weekly (0.76, P < 0.0001) or per-visit (0.73, P < 0.0001) cocaine sweat patch levels was reasonable. The correlation between the self-report of cocaine use and these same two patches, however, was lower (0.40, P < 0.05 and 0.30, P < 0.05, respectively). The results revealed no significant degradation of cocaine to BE associated with wearing the patch for a longer time. Finally, the per-visit patch provided cocaine use data on 80.5% of all study days (a total of 70), while urine toxicology and the weekly patch provided 77.4% and 76.1%, respectively. CONCLUSIONS: The present findings suggest that the PharmCheck patch might be an attractive alternative to urine toxicology for use as an outcome measure in cocaine clinical trials.