A preliminary randomized, double-blind, placebo-controlled study of the safety and efficacy of ondansetron in the treatment of cocaine dependence

Prior studies have demonstrated inefficacy among dopamine receptor antagonists for treating cocaine dependence. An alternative approach would be to investigate the ability of indirect inhibitors of cortico-mesolimbic dopamine release, such as the 5-HT(3) receptor antagonist ondansetron, to reduce cocaine's reinforcing effects. We hypothesized that ondansetron might be more efficacious than placebo at reducing cocaine intake and promoting abstinence in cocaine-dependent individuals. In a pilot randomized, double-blind, 10-week controlled trial, 63 treatment-seeking, cocaine-dependent men and women received ondansetron (0.25 mg, 1.0 mg, or 4.0 mg twice daily) or placebo. Up to three times per week, participants were assessed on several measures of cocaine use, including urine benzoylecgonine. Cognitive behavioral therapy was administered weekly. Ondansetron was well tolerated, causing no serious adverse events. The ondansetron 4.0 mg group had the lowest dropout rate among all treatment groups and a greater rate of improvement in percentage of participants with a cocaine-free week compared with the placebo group (p = 0.02), whereas the ondansetron 1.0 mg group had a lower rate of improvement in percentage of weekly mean non-use days than did placebo recipients (p = 0.04). These results suggest the possibility of a non-linear dose-response function, with evidence supporting efficacy for the 4.0 mg group.

Methylphenidate and cocaine: A placebo-controlled drug interaction study

Up to thirty percent of cocaine addicted individuals may meet diagnostic criteria for Attention-Deficit/Hyperactivity Disorder (ADHD). Methylphenidate (MPH) is a highly effective and commonly used treatment for ADHD but, like cocaine, is a cardiovascular and central nervous system stimulant with the potential to cause toxicity at high doses. The present study was undertaken to investigate the likelihood of a toxic reaction in individuals who use cocaine while concurrently taking MPH. Seven non-treatment seeking cocaine-dependent individuals completed this placebo-controlled, crossover study with two factors: Medication (placebo, 60 mg MPH, 90 mg MPH) and Infusion (saline, 20 mg cocaine, 40 mg cocaine). Physiological measures included vital signs, adverse events, and electrocardiogram. Subjective response was measured with visual analog scale (VAS) ratings of craving and drug effect. Cocaine pharmacokinetic parameters were calculated for each participant at each drug combination, using a non-compartmental model. MPH was well tolerated, did not have a clinically significant impact on cocaine's physiological effects, and decreased some of the positive subjective effects of cocaine. MPH did not significantly alter the pharmacokinetics of cocaine. The study results suggest that MPH at the doses studied can likely be used safely in an outpatient setting with active cocaine users.

Modafinil influences the pharmacokinetics of intravenous cocaine in healthy cocaine-dependent volunteers

OBJECTIVE

To determine if modafinil, a putative treatment for cocaine dependence, influences the pharmacokinetics of intravenous cocaine in otherwise healthy cocaine-dependent volunteers.

METHODS

Cocaine 20 or 40 mg was administered intravenously on consecutive days over 1 minute at baseline and after modafinil administration at each of two dosages of 400 and 800 mg/day for 7 days.

RESULTS

Twelve subjects completed the clinical protocol. Compared with baseline, the cocaine peak plasma concentration was decreased after both the 20 and 40 mg cocaine infusions, but the reduction was only statistically significant after the 40 mg cocaine infusion (p < 0.01 after modafinil 400 mg/day; p < 0.05 after modafinil 800 mg/day). The area under the cocaine plasma concentration-time curve from 0 to 180 minutes (AUC180) was significantly decreased by modafinil administration (p < 0.01 and p < 0.001 for modafinil 400 and 800 mg/day, respectively, for the cocaine 20mg dose; p < 0.001 for the cocaine 40 mg dose at both modafinil levels). There were no significant changes in total AUC, clearance or elimination half-life of cocaine.

CONCLUSION

This study did not find evidence for a harmful pharmacokinetic interaction between modafinil and cocaine. In contrast, long-term administration of modafinil significantly decreased systemic exposure to cocaine during the first 180 minutes following intravenous cocaine administration.

Bupropion reduces methamphetamine-induced subjective effects and cue-induced craving

Bupropion is an antidepressant with stimulant properties, which inhibits the reuptake of dopamine (DA) and norepinepherine, and is purported to enhance DA neurotransmission. Bupropion is considered an appealing candidate medication for the treatment of methamphetamine dependence. The current laboratory study was set forth to assess the impact of bupropion treatment on the subjective effects produced by methamphetamine in the laboratory. We also assessed the effects of bupropion treatment on craving elicited by exposure to videotaped methamphetamine cues. A total of 26 participants were enrolled and 20 completed the entire study (n=10 placebo and n=10 bupropion, parallel groups design). Bupropion treatment was associated with reduced ratings of 'any drug effect' (p<0.02), and 'high' (p<0.02) following methamphetamine administration. There was also a significant bupropion-by-cue exposure interaction on General Craving Scale total score (p<0.002), and on the Behavioral Intention subscale (p<0.001). Overall, the data reveal that bupropion reduced acute methamphetamine-induced subjective effects and reduced cue-induced craving. Importantly, these data provide a rationale for the evaluation of bupropion in the treatment of methamphetamine dependence.

Intravenous Cocaine and QT Variability

BACKGROUND

Dynamic instability in cardiac repolarization may contribute to drug-induced arrhythmogenesis. We hypothesized that intravenous cocaine would significantly destabilize repolarization as measured by QT variability.

METHODS AND RESULTS

Twenty-nine cocaine-experienced volunteers not seeking treatment for cocaine addiction received randomized, sequential intravenous infusions of placebo or cocaine (20 and 40 mg). Five-minute epochs of digitized ECG were recorded 10 minutes before, during, and at intervals following the infusions. QT variability was measured using a semiautomated method and expressed as the log ratio of normalized QT variance to normalized heart rate variance (QTVI). Seventeen subjects received a repeat course of cocaine infusions 1 week later. Placebo infusion resulted in a small but significant increase in QTVI, while cocaine caused a highly significant, dose-dependent increase in QTVI that peaked at 10 minutes and dissipated by 45 minutes following infusion (P < 0.0001). The increase in QTVI was reproducible at 1 week (P = 0.8).

CONCLUSIONS

Cocaine injection results in a significant dose-dependent increase in QT variability as indexed by QTVI. This destabilizing effect on repolarization may increase vulnerability to reentrant arrhythmias and may partially explain an increased risk of sudden cardiac death associated with cocaine use.

A Placebo Controlled, Double-Blind Study of Mecamylamine Treatment for Cocaine Dependence in Patients Enrolled in an Opiate Replacement Program

A placebo controlled, double-blind trial of mecamylamine treatment of cocaine dependence was performed in methadone or LAAM maintained subjects who met DSM-IV criteria for cocaine dependence. After an eight-week placebo run-in screening period, 35 subjects were randomly assigned to receive either mecamylamine (6 mg/day) or placebo transdermal patches for a 16-week treatment period. Outcome measures included quantitative urine benzoylecognine (BE) levels, self-report of cocaine use, cocaine craving, global impression scores, mood, retention, and safety. Mecamylamine was well tolerated, and study retention did not differ by treatment group. Evidence for cocaine use, based on urine BE levels and cocaine abstinence rates, did not differ by treatment group. Self reported cocaine use, cocaine craving, and global impression scores showed moderate improvement in both groups, with a significantly greater reduction in cocaine craving (p < 0.05) and self-rated severity of cocaine dependence (p < 0.05) in the placebo group. This pilot study does not support the effectiveness of mecamylamine for the treatment of cocaine dependence in methadone or LAAM maintained patients.

A comprehensive assessment of the safety of intravenous methamphetamine administration during treatment with selegiline

Selegiline (L-deprenyl) is a selective irreversible monoamine oxidase B inhibitor shown to be effective in the treatment of Parkinson's and Alzheimer's diseases. Recent evidence suggests that selegiline may also be useful in treating specific aspects of cocaine and nicotine dependence, generating interest in this compound for the treatment of methamphetamine addiction. To investigate this, we performed a randomized, single-blind, placebo-controlled study to evaluate the safety of selegiline treatment (as compared to placebo), concurrent with intravenous methamphetamine (15 or 30 mg). Secondary study objectives included determinations of plasma levels of selegiline and its metabolites, evaluating whether selegiline administration altered the pharmacokinetics of methamphetamine or its metabolites, and evaluating whether selegiline treatment alters the subjective responses to methamphetamine. Twenty-four methamphetamine-dependent participants were randomized to treatment, and 9 of these (N = 5 selegiline, N = 4 placebo) completed the entire protocol. The principal finding from this study was that intravenous administration of moderate doses of methamphetamine was safely tolerated during treatment with selegiline. No participants had electrocardiogram changes, and there were no meaningful differences in any laboratory values either between groups at screening or as a result of the study procedures. In general, adverse events were mild or moderate, and no subjects were discontinued due to adverse events or serious adverse events. Selegiline treatment did not enhance any of the cardiovascular changes (heart rate, blood pressure) produced by methamphetamine administration. Selegiline treatment slightly increased methamphetamine associated "bad effects" but did not alter any other subjective effects. The elimination half-life of methamphetamine was approximately 12 h, and selegiline did not alter clearance of methamphetamine. The available data suggest that selegiline is likely to be safe if used as a pharmacotherapy for methamphetamine dependence.

Safety of intravenous methamphetamine administration during treatment with bupropion

RATIONALE

Methamphetamine dependence is a growing problem for which no medication treatments have proven effective.

OBJECTIVES

We evaluated bupropion, an antidepressant with beneficial effects for the treatment of nicotine dependence, in patients with methamphetamine dependence, to assess the safety and tolerability of methamphetamine administration during bupropion treatment.

METHODS

Twenty-six participants entered the study and 20 completed the protocol. Participants received intravenous methamphetamine (0, 15, and 30 mg) before and after randomization to twice-daily bupropion (150 mg SR) or matched placebo. Dependent measures included cardiovascular effects of methamphetamine, methamphetamine and amphetamine pharmacokinetics, and peak and trough plasma concentrations of bupropion and its metabolites.

RESULTS

Bupropion treatment was well tolerated, with bupropion- and placebo-treated groups reporting similar rates of adverse events. Methamphetamine administration was associated with expected stimulant cardiovascular effects, and these were not accentuated by bupropion treatment. Instead, there was a trend for bupropion to reduce methamphetamine-associated increases in blood pressure and a statistically significant reduction in methamphetamine-associated increases in heart rate. Pharmacokinetic analysis revealed that bupropion treatment reduced the plasma clearance of methamphetamine and also reduced the appearance of amphetamine in the plasma. Methamphetamine administration did not alter the peak and trough plasma concentrations of bupropion or its metabolites.

CONCLUSIONS

Methamphetamine administration was well tolerated during bupropion treatment. There was no evidence of additive cardiovascular effects when the drugs were coadministered. This study provides initial evidence for the safety of prescribing bupropion for the treatment of methamphetamine abuse and dependence. The impact of bupropion treatment in patients who abuse larger doses of methamphetamine remains undetermined.

Medication development for addictive disorders: the state of the science

In 1989, the National Institute on Drug Abuse (NIDA) established its Medications Development Program. This program has concentrated on developing pharmacotherapies for opiate and cocaine dependence and, more recently, for methamphetamine and cannabis dependence. The major goals of this program are to optimize existing treatments and to expand treatment options for physicians and patients. This review will concentrate on the development of pharmacotherapies for the following substance abuse disorders: opiate, cocaine, methamphetamine, and cannabis dependence. Left untreated, opiate and stimulant dependence are responsible for significant morbidity and mortality. For example, use of illicit opiates is associated with an increased risk of hepatitis C infection, HIV infection, and other medical consequences, e.g., an overdose. The NIDA Medications Development Program has had success in developing, with pharmaceutical partners, levomethadyl acetate, buprenorphine, and buprenorphine/naloxone for opiate dependence. Moreover, several marketed medications have shown promise in reducing cocaine use. Of interest, these medications likely operate through diverse neurochemical mechanisms, suggesting that combination therapy may be a rational next step that could increase treatment gains further in cocaine-dependent patients. The Medications Development Program has also identified multiple neuronal mechanisms that are altered by chronic administration of drugs of abuse. Advances in neuroscience have identified changes in conditioned cueing, drug priming, stress-induced increases in drug intake, and reduced frontal inhibitory mechanisms as all being possible for the development of, maintenance of, and possible relapse to, addiction. Potential medications that modulate these mechanisms are highlighted.

Pharmacotherapy and other treatments for cocaine abuse and dependence

PURPOSE OF REVIEW

This review examines progress being made in the treatment of cocaine abuse and dependence, with a particular focus on pharmacotherapies. Medications with apparently very different mechanisms of action have been reported to reduce cocaine use in controlled clinical trials in outpatient settings. This review will summarize the latest findings in this area.

RECENT FINDINGS

Of all the medications tested to date, disulfiram has demonstrated the most consistent effect to reduce cocaine use. Several medications have been reported to reduce cocaine use in double-blind, placebo-controlled clinical trials, namely baclofen, modafinil, tiagabine, and topiramate. All pharmacotherapy trials in cocaine-dependent patients include a behavioral therapy that is common to all participants. Consequently, these pharmacotherapy trials can be considered to evaluate whether the medication is adding to the effect of the behavioral therapy.

SUMMARY

Confirmatory clinical studies are necessary to replicate the initial efficacy findings for baclofen, modafinil, tiagabine, and topiramate. More research is needed in both cocaine and cocaine-alcohol dependent populations. Once confirmatory studies have been carried out, testing of rational medication combinations with different behavioral therapies is an obvious next step to increase the ability to manage cocaine dependence.

Metyrapone and cocaine: A double-blind, placebo-controlled drug interaction study

Pre-clinical research suggests that suppression of adrenocorticosteroid synthesis might decrease susceptibility to stress-induced relapse. Metyrapone effectively suppresses cortisol synthesis and thus might have promise as a cocaine dependence treatment. The present inpatient study evaluated the interaction of metyrapone and cocaine to assess the safety of conducting an outpatient trial. Twelve nontreatment-seeking cocaine-dependent individuals completed this double-blind, placebo-controlled, crossover study with two factors: medication (750 mg of metyrapone vs. placebo) and infusion (40 mg of cocaine vs. saline). Safety measures included vital signs, adverse events, and electrocardiogram. Efficacy measures included visual analog scale (VAS) ratings of craving and drug effect. Neuroendocrine measures included cortisol and ACTH. As predicted, metyrapone was well tolerated and did not exacerbate cocaine's physiological effects. Also as predicted, metyrapone did not significantly alter cocaine's subjective effects. The results of the present study suggest that metyrapone at the dose studied can likely be used safely in an outpatient study with active cocaine users.

Cocaine Rapid Efficacy Screening Trial (CREST): a paradigm for the controlled evaluation of candidate medications for cocaine dependence

AIM

Development of effective medications for the treatment of cocaine dependence remains a major priority for the National Institute on Drug Abuse (NIDA) at the National Institutes of Health. The Cocaine Rapid Efficacy Screening Trial (CREST) paradigm was developed by the Division of Treatment Research and Development (DT R&D) at NIDA with the goal of enhancing pilot clinical trial validity when systematically assessing a range of medications and drug classes for potential utility in treatment of cocaine dependence.

DESIGN

CREST utilizes a randomized, controlled, parallel group, blinded methodology for comparing one or more marketed medications against a standard, pharmaceutical grade placebo. The trial design is comprised of a flexible 24-week screening/baseline period followed by randomization to an 8-week treatment period.

MEASURES

Standard measures of outcomes for the CREST included urinary benzoylecgonine (primary metabolite of cocaine), retention, cocaine craving, depression, clinical global impression and HIV-risk behaviors. In order to facilitate comparisons of data from the CREST studies across sites, drug classes and time, standardized procedures, measures and psychosocial counseling were used.

RESULTS

A total of 19 medications were evaluated in out-patient treatment research clinics in Boston, Cincinnati, Los Angeles, New York and Philadelphia.

CONCLUSIONS

Findings supported decisions to move forward three medications (cabergoline, reserpine, tiagabine) using full-scale, adequately powered, randomized placebo-controlled trial designs. Lessons learned from the CREST experience continue to shape cocaine pharmacotherapy trial design and execution.

Retrospective analyses of pooled data from CREST I and CREST II trials for treatment of cocaine dependence

AIM

To analyze pooled data from the Cocaine Rapid Evaluation Screening Trial (CREST). Pooling data from these small pilot trials into four major drug classes permitted data exploration for treatment and covariate effects with increased sample size.

DESIGN

Small pilot trials were conducted to screen fifteen medications as prospective treatments for cocaine dependence. Studies included a flexible 2-week to 4-week screening/baseline period followed by an 8-week randomized treatment condition. Participants were randomized equally to one of up to three active medications or placebo.

SETTING

Five Medications Development Research Units at the five academic centers of University of Cincinnati, New York University, University of Pennsylvania, University of California Los Angeles and Boston University.

PARTICIPANTS

The pooled data set consisted of 357 total subjects. Standardized inclusion and exclusion criteria were employed in subject selection to enhance consistency of cocaine-dependent study participants across all sites (see reports on individual trials in this supplement for details). All participants provided at least two urine samples that were positive for cocaine metabolite during a two-week period prior to being randomized.

INTERVENTION

All subjects in these trials, those randomized to placebo and active medications, received active treatment in the form of evidence-based cognitive behavioral therapy.

MEASURES

Quantitative urine benzoylecgonine (BE), self-report of cocaine use, and total Brief Substance Craving Scale (BSCS) scores were compared between each class of medication and its matched-placebo group.

FINDINGS

Regression analysis of pooled data did not identify any statistically significant differences between treatment and matched-placebo for any of the four classes. Exploration of the effects of baseline covariates indicated that gender and African American status were associated significantly with outcome. Female gender was consistently associated with poorer outcomes for medication and placebo groups, while the direction of association between African American status and outcome differed by treatment groups. Retention was also examined: dropout rates may have been somewhat higher for placebo than treatment groups during the early active-treatment period. Classification trees were used to identify characteristics of subjects who were abstinent for at least two weeks during the eight-week trial; only 4.0% of females while 17.9% of males achieved this criterion.

CONCLUSIONS

Results presented here may prove useful for planning future clinical trials for therapies targeting cocaine dependence.

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.

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.

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.

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.

Transdermal selegiline and intravenous cocaine: safety and interactions

RATIONALE

Because the dopamine system appears to be involved in both acute and chronic effects of cocaine, medication development efforts for cocaine addiction have focused largely on agents that interact with the dopamine system. Selegiline, a selective monoamine oxidase B inhibitor, indirectly modulates dopamine levels, and research suggests selegiline may modify subjective effects of cocaine.

OBJECTIVES

To evaluate further the safety and potential of transdermal selegiline as a treatment for cocaine dependence, interactions between transdermal selegiline and intravenous cocaine were studied in cocaine-dependent volunteers.

METHODS

Pharmacokinetics and subjective, physiological, and endocrinological effects of intravenous cocaine (0,20 and 40 mg) were evaluated both before and during transdermal selegiline treatment (20 mg/day, 10 days) in 12 cocaine-dependent subjects. A transdermal selegiline formulation was used to avoid the risks associated with oral administration of MAO inhibitors.

RESULTS

Selegiline attenuated some physiological (systolic blood pressure and heart rate) and subjective (good effects, liking, stimulated, high, desire for cocaine) effects of cocaine. Selegiline did not affect cocaine's pharmacokinetics or cocaine-induced prolactin decrease and growth hormone increase.

CONCLUSIONS

The combined administration of the transdermal selegiline patch and up to 40 mg cocaine was well tolerated. Selegiline may reduce physiological and subjective effects of cocaine. A randomized trial is needed to evaluate the efficacy of selegiline for cocaine abuse.

Biological markers of cocaine addiction: implications for medications development

The search for effective medications for cocaine addiction has been elusive. The failure to find such medications so far could be due to poor understanding of the underlying biology both in the premorbid condition and following the disease state of chronic cocaine use. Population heterogeneity could be a major factor in response to medications. In an attempt to highlight the issue of biomarkers we reviewed physiological, neuroendocrine and neuroimaging studies to identify specific biological changes/markers that could be used to characterize subgroups among chronic cocaine users. Merging the biology within medications studies of cocaine abusers could prove useful for targeting specific pharmacological agents to subgroups of patients, prediction of response to medication and relapse to use.

Evidence that L-deprenyl treatment for one week does not inhibit MAO A or the dopamine transporter in the human brain

In this study, we investigated whether treatment with L-deprenyl, a selective monoamine oxidase B (MAO B) inhibitor, also inhibits MAO A or the dopamine transporter in the human brain. Six normal volunteers (age 46+/-6 yrs) had two PET sessions, one at baseline and one following L-deprenyl (10 mg/day) for 1 week. Each session included one scan with [11C]clorgyline (to assess MAO A) and one scan 2 hours later with [11C]cocaine (to assess dopamine transporter availability). A 3-compartment model was used to compare the plasma-to-brain transfer constant, K1 (a function of blood flow) and lambdak3 (a kinetic term proportional to brain MAO A) before and after treatment. Dopamine transporter availability was measured as the ratio of distribution volumes of the striatum to cerebellum (DVR) which is equal to Bmax/KD +1. L-Deprenyl treatment for 1 week did not affect either brain MAO A activity or dopamine transporter availability. There was a non-significant trend for an increase in K1 after L-deprenyl. These results confirm that L-deprenyl after one week of treatment at doses typically used clinically is selective for MAO B and that it does not produce a measurable affect on the dopamine transporter, suggesting that MAO A inhibition and dopamine transporter blockade do not contribute to its pharmacological effects.

Clonidine does not potentiate the antipsychotic effects of neuroleptics in chronically ill patients

Clonidine is a centrally acting antihypertensive and has been prescribed widely for more than 20 years. Because it decreases central norepinephrine activity, clonidine has been investigated as an antipsychotic. In most of the preliminary studies, clonidine was tested as the sole antipsychotic agent. We performed a double-blind, placebo-controlled, crossover study to compare a placebo plus a neuroleptic to clonidine plus a neuroleptic in a group of 16 chronically psychotic patients. Of these 16, 3 dropped out secondary to side effects of the clonidine and 1 withdrew from the study. The clonidine dosage varied from 0.2 to 0.6 mg per day. The concurrent neuroleptic (one of the following: haloperidol, thiothixene, thioridazine, mesoridazine, or fluphenazine) averaged 34 mg per day of haloperidol equivalents. Symptoms were monitored using the Psychiatric Symptoms Assessment Scale. The data provided evidence that a clonidine/neuroleptic combination was not more effective than a neuroleptic alone in this group of patients. These data suggest that the central antinorepinephrine activity of a neuroleptic is not potentiated further by clonidine.

Coadministration of fluvoxamine increases serum concentrations of haloperidol

Four patients with chronic schizophrenia were treated with a combination of fluvoxamine, haloperidol, and benztropine. The combination significantly impaired performance on tests of delayed recall memory and attentional function. Haloperidol concentrations in serum were monitored in three patients and were robustly elevated by fluvoxamine.

Structural abnormalities in deficit and nondeficit schizophrenia

OBJECTIVE

Previous studies have suggested the involvement of the frontal and parietal cortices and thalamus in a neural circuit underlying the production of primary enduring negative or deficit symptoms of schizophrenia. The purpose of this study was to examine whether structural changes in the proposed circuit are associated with the production of deficit symptoms.

METHOD

Magnetic resonance imaging was used to measure the volume of selected circuit brain regions (i.e., the prefrontal region and caudate) and noncircuit brain regions (i.e., the amygdala/hippocampus complex) in 17 deficit and 24 nondeficit schizophrenic outpatients and 30 normal comparison subjects.

RESULTS

Right and left total prefrontal volumes discriminated deficit from nondeficit patients, with prefrontal volumes being smaller in nondeficit patients. There were no differences between the two schizophrenic subgroups in left caudate or right and left amygdala/hippocampus complex volumes. The right caudate was larger in deficit patients, but the difference between the two schizophrenic subgroups was not significant. There were no differences between deficit and normal subjects on any prefrontal region measure. Nondeficit patients had smaller total right and left prefrontal volumes than normal subjects. Both schizophrenic subgroups had larger left caudate volumes and smaller right and left amygdala/hippocampus complex volumes than the normal subjects. There was a trend for deficit patients to have larger right caudate volumes.

CONCLUSIONS

These results suggest that structural changes in the prefrontal region are not responsible for deficit symptoms. The caudate, particularly the right caudate, may be associated with the production of these symptoms.