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Background: Developing efficacious medications to treat methamphetamine dependence is a global challenge in public health. Topiramate (TPM) is undergoing evaluation for this indication. The molecular mechanisms underlying its effects are largely unknown. Examining the effects of TPM on genome-wide gene expression in methamphetamine addicts is a clinically and scientifically important component of understanding its therapeutic profile., Methods: In this double-blind, placebo-controlled clinical trial, 140 individuals who met the DSM-IV criteria for methamphetamine dependence were randomized to receive either TPM or placebo, of whom 99 consented to participate in our genome-wide expression study. The RNA samples were collected from whole blood for 50 TPM- and 49 placebo-treated participants at three time points: baseline and the ends of weeks 8 and 12. Genome-wide expression profiles and pathways of the two groups were compared for the responders and non-responders at Weeks 8 and 12. To minimize individual variations, expression of all examined genes at Weeks 8 and 12 were normalized to the values at baseline prior to identification of differentially expressed genes and pathways., Results: At the single-gene level, we identified 1054, 502, 204, and 404 genes at nominal P values < 0.01 in the responders vs. non-responders at Weeks 8 and 12 for the TPM and placebo groups, respectively. Among them, expression of 159, 38, 2, and 21 genes was still significantly different after Bonferroni corrections for multiple testing. Many of these genes, such as GRINA, PRKACA, PRKCI, SNAP23, and TRAK2, which are involved in glutamate receptor and GABA receptor signaling, are direct targets for TPM. In contrast, no TPM drug targets were identified in the 38 significant genes for the Week 8 placebo group. Pathway analyses based on nominally significant genes revealed 27 enriched pathways shared by the Weeks 8 and 12 TPM groups. These pathways are involved in relevant physiological functions such as neuronal function/synaptic plasticity, signal transduction, cardiovascular function, and inflammation/immune function., Conclusion: Topiramate treatment of methamphetamine addicts significantly modulates the expression of genes involved in multiple biological processes underlying addiction behavior and other physiological functions.

Background: As reported previously, 140 methamphetamine-dependent participants at eight medical centers in the U.S. were assigned randomly to receive topiramate (N=69) or placebo (N=71) in a 13-week clinical trial. The study found that topiramate did not appear to reduce methamphetamine use significantly for the primary outcome (i.e., weekly abstinence from methamphetamine in weeks 6-12). Given that the treatment responses varied considerably among subjects, the objective of this study was to identify the heterogeneous treatment effect of topiramate and determine whether topiramate could reduce methamphetamine use effectively in a subgroup of subjects., Methods: Latent variable analysis was used for the primary and secondary outcomes during weeks 6-12 and 1-12, adjusting for age, sex, and ethnicity., Results: Our analysis of the primary outcome identified 30 subjects as responders, who either reduced methamphetamine use consistently over time or achieved abstinence. Moreover, topiramate recipients had a significantly steeper slope in methamphetamine reduction and accelerated to abstinence faster than placebo recipients. For the secondary outcomes in weeks 6-12, we identified 40 subjects as responders (who had significant reductions in methamphetamine use) and 65 as non-responders; topiramate recipients were more than twice as likely as placebo recipients to be responders (odds ratio=2.67; p=0.019). Separate analyses of the outcomes during weeks 1-12 yielded similar results., Conclusions: Methamphetamine users appear to respond to topiramate treatment differentially. Our findings show an effect of topiramate on the increasing trend of abstinence from methamphetamine, suggesting that a tailored intervention strategy is needed for treating methamphetamine addiction., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

Aims:   Topiramate has shown efficacy at facilitating abstinence from alcohol and cocaine abuse. This double-blind, placebo-controlled out-patient trial tested topiramate for treating methamphetamine addiction., Design:   Participants (n = 140) were randomized to receive topiramate or placebo (13 weeks) in escalating doses from 25 mg/day [DOSAGE ERROR CORRECTED] to the target maintenance of 200 mg/day in weeks 6-12 (tapered in week 13). Medication was combined with weekly brief behavioral compliance enhancement treatment., Setting:   The trial was conducted at eight medical centers in the United States., Participants:   One hundred and forty methamphetamine-dependent adults took part in the trial., Measurements:   The primary outcome was abstinence from methamphetamine during weeks 6-12. Secondary outcomes included use reduction versus baseline, as well as psychosocial variables., Findings:   In the intent-to-treat analysis, topiramate did not increase abstinence from methamphetamine during weeks 6-12. For secondary outcomes, topiramate reduced weekly median urine methamphetamine levels and observer-rated severity of dependence scores significantly. Subjects with negative urine before randomization (n = 26) had significantly greater abstinence on topiramate versus placebo during study weeks 6-12. Topiramate was safe and well tolerated., Conclusions:   Topiramate does not appear to promote abstinence in methamphetamine users but can reduce the amount taken and reduce relapse rates in those who are already abstinent., (© 2011 The Authors, Addiction © 2011 Society for the Study of Addiction.)

Methamphetamine dependence is an increasing public health problem in the United States. No efficacious medication for methamphetamine dependence has been developed. As ondansetron, a 5-HT3 receptor antagonist and modulator of cortico-mesolimbic dopamine function, has been shown to reduce some of the rewarding effects of d-amphetamine in animal and human laboratory studies, we decided to test whether it would be superior to placebo at reducing methamphetamine use. In a preliminary, multi-site, randomized, double-blind, 8-wk controlled trial, 150 methamphetamine-dependent men and women received ondansetron (0.25 mg, 1 mg, or 4 mg b.i.d.) or placebo. Participants were assessed on several measures of methamphetamine use including urine methamphetamine level up to three times per week. As a psychosocial adjunct to the medication condition, cognitive behavioural therapy also was administered three times per week. Ondansetron was well tolerated and was less likely than placebo to be associated with serious adverse events. Nevertheless, none of the ondansetron doses was superior to placebo at decreasing any of the measures of methamphetamine use, withdrawal, craving, or clinical severity of methamphetamine dependence. Our preliminary results do not support the utility of ondansetron, at the doses tested, as a treatment for methamphetamine dependence. These findings should be viewed in light of the possibility that a less intensive cognitive behavioural therapy regimen might have yielded more positive results in this initial phase II trial exploring for the efficacy of ondansetron.

Previously, we have shown that orally administered topiramate, a sulfamate-substituted fructopyranose derivative, appears to accentuate rather than diminish some aspects of methamphetamine-induced positive subjective mood and cognitive performance. One possible mechanism by which this might occur would be for topiramate to increase plasma methamphetamine level. Such an effect also would be expected to enhance methamphetamine-induced hemodynamic response. We, therefore, studied -- in the same experiment from which the previous findings originated -- the effects of topiramate on the kinetic profile and hemodynamic response to methamphetamine. In a 27-day inpatient study, 10 methamphetamine-dependent individuals participated in a double-blind, placebo-controlled, cross-over design, with oral doses of topiramate (0, 100, and 200 mg) administered as a pretreatment before intravenous doses of methamphetamine (0, 15, and 30 mg). The 3x3 factorial combination of topiramate and methamphetamine resulted in a sequence of the nine treatments administered to each subject in an order determined by a 9x9 Latin Square design. Methamphetamine alone was associated with prototypical increases in hemodynamic response that were not altered in the presence of topiramate. While there was no significant kinetic interaction between topiramate and methamphetamine, there was a non-significant trend for topiramate to increase plasma methamphetamine level. No significant adverse events were reported. The combination of topiramate and methamphetamine at pharmacologically relevant doses appears to be safe. Larger laboratory studies with chronic dosing regimens are needed to establish whether or not there is a kinetic interaction between topiramate and methamphetamine.

Clinical studies have shown that topiramate, a sulphamate-substituted fructopyranose derivative, might be an efficacious treatment for alcohol dependence, smoking cessation within an alcohol-dependent population, and cocaine dependence. Mechanistically, topiramate's therapeutic effects have been hypothesized to be due to inhibition of cortico-mesolimbic dopamine function, the primary substrate that governs the acquisition, maintenance, and reinstatement of goal-directed behaviour towards seeking abused drugs. Predicated on this hypothesis, we tested in 10 methamphetamine-dependent individuals (three females) whether low- or high-dose (15 or 30 mg i.v.) methamphetamine-induced positive subjective effects and reinforcement can be antagonized by low- or high-dose (100 or 200 mg orally) topiramate using a placebo-controlled, cross-over, factorial design. Methamphetamine administration was associated with orderly, prototypical, and significant increases on measures of stimulation, euphoria, craving, and reinforcement; however, some dysphoric symptoms also emerged. Topiramate alone showed a non-significant trend towards mild reductions in positive mood and reinforcement; yet topiramate appeared to accentuate the appreciation of methamphetamine-induced stimulation and euphoria significantly, but not craving or reinforcement. The experimental combination of topiramate and methamphetamine appeared to be safe and well tolerated, with few adverse events. Acute dosing with up to 200 mg topiramate appears to enhance, rather than attenuate, the positive subjective effects of methamphetamine. Perhaps this indicates a partial inhibition of methamphetamine's reinforcing effects. Thus, testing chronically administered or higher doses, or both, of topiramate would be necessary to determine conclusively whether or not it can attenuate the positive subjective and reinforcing effects of methamphetamine.

Methamphetamine-dependent individuals often cite the need to maintain enhanced cognitive performance and attention as a reason for continuing or relapsing to drug-taking. Further, methamphetamine addicts might not comply with taking a potentially therapeutic medication if it had a profound effect on these cognitive processes. Topiramate, a sulfamate-substituted fructopyranose derivative, has been suggested as a putative therapeutic medication for treating methamphetamine dependence. Examination of topiramate's effects on cognitive performance and attention is a clinically and scientifically important component of understanding its potential therapeutic profile. In 10 male and female individuals who met DSM-IV criteria for methamphetamine dependence, we examined the effects of low (50 mg b.i.d.)- and high (100 mg b.i.d.)-dose topiramate - in both the presence and absence of low (15 mg)- and high (30 mg)-dose intravenous methamphetamine--on cognitive performance, attention, and concentration on the rapid visual information processing task and the digit symbol substitution test. Intravenous methamphetamine enhanced cognitive performance, attention, and concentration among recently withdrawn methamphetamine addicts--an effect that hitherto had not been well characterized. Topiramate's cognitive effects were mixed and rather paradoxical, with a tendency to improve attention and concentration both alone and in the presence of methamphetamine while worsening psychomotor retardation. No deleterious interaction occurred between topiramate and methamphetamine on any of these cognitive processes. While clinical studies with topiramate should prepare participants for possible psychomotor retardation, the cognitive effects profile observed would not likely present an important obstacle to compliance in motivated patients. Topiramate's complicated cognitive effects among methamphetamine addicts need more comprehensive examination.

Background: Massive hypertensive crises relating to cerebrovascular accidents such as strokes or ruptured aneurysms, or cardiovascular dysfunction and toxicity, are an important cause of morbidity and mortality associated with cocaine or methamphetamine use. Experimentally administered, pharmacologically effective doses of cocaine and methamphetamine may serve as a model for studying the effects of these drugs on hemodynamic response and for examining the potential utility of the antihypertensive and dihydropyridine-class calcium channel antagonist isradipine to block these effects. We therefore examined, in two separate experiments of similar design conducted contemporaneously, the hemodynamic effects of cocaine or methamphetamine in the presence and absence of isradipine., Methods: In both experiments (total N = 31), isradipine pretreatment was provided to cocaine- or methamphetamine-dependent male and female subjects before intravenous administration of low and high doses of cocaine (0.325 or 0.650 mg/kg) or methamphetamine (15 or 30 mg), respectively, on separate test days., Results: Both cocaine and methamphetamine administration produced predicted elevations in blood pressure (with peak response between 1 and 3 min after infusion). Apart from tachycardia, no arrhythmias were reported. Isradipine significantly reduced stimulant-associated increases in all measures of blood pressure except pulse pressure, but tended to enhance the effects of these drugs on heart rate., Conclusions: Clinical studies are needed to determine whether isradipine is therapeutically efficacious in preventing hypertensive crises and the associated cerebrovascular and cardiovascular sequelae in cocaine- or methamphetamine-dependent individuals. As there is no established pharmacotherapy for treating cocaine or methamphetamine dependence, identification of a medication that reduces the harmful medical consequences of these drugs would be scientifically and clinically important.

Rationale: While the effects of d-amphetamine in increasing performance have been established, there is a paucity of information on the effects of methamphetamine on cognition in drug-naive subjects, and no published information on the effects of intravenous methamphetamine administration in dependent individuals. The dihydropyridine-class calcium channel antagonist, isradipine, has been posited as a putative treatment to prevent methamphetamine-associated hypertensive crisis and its sequelae. Yet, isradipine's effects on cognitive performance in methamphetamine-dependent individuals are not known., Objective: Since individuals whose dependence on methamphetamine is attributable to the need to enhance performance may be loath to take a cognition-impairing medication, even for the treatment of life-threatening hypertensive crisis, it would be important to determine isradipine's effects on performance., Methods: We therefore examined in a blinded, placebo-controlled, crossover design the cognitive effects of low and high doses of intravenous methamphetamine (15 mg and 30 mg, respectively) in both the presence and absence of isradipine., Results: Intravenous d-methamphetamine produced dose-dependent increases in attention, concentration, and psychomotor performance. Isradipine, both with and without methamphetamine, had a modest effect to decrease attention., Conclusion: Our results do not support the further testing of isradipine as a medication for improving the cognitive impairments that have been associated with chronic methamphetamine use.

Abstract Rationale: Dopamine (DA) pathways in the midbrain mediate d-methamphetamine's rewarding effects associated with its abuse liability. Isradipine, a dihydropyridine-class calcium channel antagonist, reduces the rewarding effects of psychostimulants such as cocaine and d-amphetamine, presumably by antagonizing these central DA pathways. This is the first experiment to test the hypothesis that the rewarding effects of dmethamphetamine, like other psychostimulants, can be reduced by isradipine. Objective: We studied the effects of high dose isradipine (0.21 mg/kg orally), on the positive subjective effects associated with the abuse liability of low and high dose d-methamphetamine (0.21 mg/kg and 0.42 mg/kg orally, respectively). Methods: Using a double-blind, double-dummy, placebo-controlled, Latin-Square, cross-over design, 18 healthy male and female volunteers received each of the following six treatments separated by a rest period of 2-7 days: a) placebo+placebo; b) low-dose d-methamphetamine+placebo); c) highdose d-methamphetamine+placebo; d) high dose isradipine+placebo); e) low-dose d-methamphetamine+high dose isradipine, and f) high-dose d-methamphetamine+high dose isradipine. Results: d-Methamphetamine produced orderly increases in positive subjective measures of both stimulation and mood. Pre-treatment with isradipine significantly reduced some of these positive subjective effects and craving for d-methamphetamine. Conclusion: Isradipine as an anti-reward or craving reducing medication is a promising therapeutic agent for the treatment of d-methamphetamine dependence. [ABSTRACT FROM AUTHOR]