Naltrexone for heroin dependence treatment in St. Petersburg, Russia

Naltrexone may be more effective for treating opioid (heroin) dependence in Russia than in the U.S. because patients are mostly young and living with their parents, who can control medication compliance. In this pilot study we randomized 52 consenting patients who completed detoxification in St. Petersburg to a double blind, 6-month course of biweekly drug counseling and naltrexone, or counseling and placebo naltrexone. Significant differences in retention and relapse favoring naltrexone were seen beginning at 1 month and continuing throughout the study. At the end of 6 months, 12 of the 27 naltrexone patients (44.4%) remained in treatment and had not relapsed as compared to 4 of 25 placebo patients (16%; p<0.05). Since heroin dependence is the main way HIV is being spread in Russia, naltrexone is likely to improve treatment outcome and help reduce the spread of HIV if it can be made more widely available.     

Does pregnancy affect outcome of methadone maintenance treatment?

Studies of pregnant women receiving methadone maintenance have tended to focus on teratogenic, prenatal, and neonatal issues. We are not aware of any controlled studies comparing pregnant to non-pregnant heroin-addicted women in methadone treatment. This article presents findings from a study examining treatment outcome between pregnant and non-pregnant participants in a metropolitan methadone-maintenance program. Participants were 51 pregnant women and 51 non-pregnant women enrolled in a methadone maintenance program between 1994 and 2003. Groups were compared on demographic characteristics, psychiatric comorbidity, urinalysis results and retention rates. Groups were comparable in terms of most demographic characteristics and severity of addiction at intake. Groups did not differ significantly in terms of urinalysis results or retention rates. While most women reduced their drug use, a majority of both groups continued to use illicit drugs at least occasionally. Psychiatric comorbidity was significantly different with the non-pregnant group being more psychiatrically disordered. Clinical implications are discussed.     

HIV/AIDS risk behaviors and correlates of injection drug use among drug users in Pakistan

We studied prevalence and correlates of injection drug use, awareness of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), and risky behaviors among drug users serviced by a nongovernmental organization catering to drug users in three Pakistani cities (Quetta, Peshawar, and Rawalpindi). Logistic regression analysis was used to identify correlates of injection drug use. Of 608 drug users, 99.8% were male; median age was 32 years, and 44% were married. Most (79.8%) were Pakistani; 15.3% were Afghani. The majority used heroin (98.7%), mostly by inhalation; 15.2% injected drugs. Only 41% had heard of HIV/AIDS, and 30% had been paid for donating blood. Injection drug use and needle sharing were highest in Quetta. Injecting drug users (IDUs) were nearly twice as likely to have donated blood and to have heard about HIV/AIDS compared to other drug users. Interventions to discourage transitions to injection, increase HIV testing, and safeguard the blood supply in Pakistan are urgently needed.     

The reinstatement model of drug relapse: history,methodology and major findings

Rational and objectives. The reinstatement model is currently used in many laboratories to investigate mechanisms underlying relapse to drug seeking. Here, we review briefly the history of the model and describe the different procedures that have been used to study the phenomenon of reinstatement of drug seeking. The results from studies using pharmacological and neuroanatomical techniques to determine the neuronal events that mediate reinstatement of heroin, cocaine and alcohol seeking by acute priming injections of drugs, drug-associated cues and environmental stressors are summarized. In addition, several issues are discussed, including (1) the concordance between the neuronal mechanisms involved in drug-induced reinstatement and those involved in drug reward and discrimination, (2) the role of drug withdrawal states and periods in reinstatement of drug seeking, (3) the role of neuronal adaptations induced by exposure to drugs in relapse, and (4) the degree to which the rat reinstatement model provides a suitable preclinical model of relapse to drug taking. Conclusions. The data derived from studies using the reinstatement model suggest that the neuronal events that mediate drug-, cue- and stress-induced reinstatement of drug seeking are not identical, that the mechanisms underlying drug-induced reinstatement are to some degree different from those mediating drug discrimination or reward, and that the duration of the withdrawal period following cocaine and heroin self-administration has a profound effect on reinstatement induced by drug cues and stress. Finally, there appears to be a good correspondence between the events that induce reinstatement in laboratory animals and those that provoke relapse in humans.     

Cannabinoid modulation of the reinforcing and motivational properties of heroin and heroin-associated cues in rats

Rationale Recently, we provided evidence for a cannabinoid mechanism in relapse to cocaine seeking in rats. There is also increasing evidence for functional cross-talk between cannabinoid and opioid systems in several physiological processes. Objectives This study was designed to evaluate whether the cannabinoid system plays a role in mediating the reinforcing and motivational effects of heroin and heroin-paired stimuli. Methods Male Wistar rats were trained to self-administer heroin (50 μg/kg per infusion) on fixed (FR5) or progressive ratio schedules of reinforcement in the presence of a discriminative and discrete heroin-associated cue. The selective cannabinoid CB1 antagonist SR141716A was given 30 min before the session to determine its effect on responding for heroin. Separate groups of rats were subjected to extinction training during which heroin-associated cues were absent and no heroin was delivered. During subsequent reinstatement tests, the effects of the cannabinoid agonist HU210 and the antagonist SR141716A on reinstatement of heroin seeking were evaluated. Results The cannabinoid antagonist dose-dependently reduced responding for heroin on the FR5 schedule and to a greater extent on the progressive ratio schedule. HU210 (20 μg/kg) reinstated heroin seeking behaviour following a 2-week extinction period, whereas SR141716A dose-dependently attenuated heroin seeking that was provoked by a priming injection of heroin (0.25 mg/kg) and heroin seeking that was triggered by re-exposure to heroin paired stimuli. Conclusions The results show that the reinforcing and motivational effects of heroin and heroin-paired stimuli are mediated, at least in part, by activation of cannabinoid CB1 receptors. Therefore, the present study provides a rationale for the use of cannabinoid antagonists in the treatment of opiate addiction.     

High levels of morphine-6-glucuronide in street heroin addicts

Rationale In the body, heroin is rapidly transformed to 6-acetylmorphine (6-AM) and then to morphine, that in turn is mainly metabolized to morphine-3-glucuronide (M3G) and, at lesser extent, to morphine-6-glucuronide (M6G). Unlike M3G, M6G is a potent opioid agonist. Intravenous heroin abusers (IHU) are exposed to a wide array of drugs and contaminants that might affect glucuronidation. Objectives We assessed plasma and urine concentrations of M3G and M6G in four groups of subjects: the first two included long-term IHU either exposed to street heroin (n=8) or receiving a single IV injection of morphine (n=4), while the other two groups included non-IHU patients receiving acute IV (n=8) or chronic oral (n=6) administrations of morphine. Methods After solid phase extraction plasma and urine concentrations of morphine metabolites were determined by HPLC analyses. Results M3G accounted for the greater part of morphine glucuronides detected in body fluids of non-IHU patients treated with morphine. This pattern of metabolism remained stable across 15 days of oral administration of incremental doses of morphine. In contrast, the two groups of IHU (street heroin taking or morphine-treated subjects) showed a reduction of blood and urine M3G concentrations in favor of M6G. Consequently, M6G/M3G ratio was significantly higher in the two IHU groups in comparison with the non-IHU groups. Conclusions Chronic exposure to street heroin causes a relative increase in concentrations of the active metabolite, M6G. Since the pattern of M6G action seems closer to heroin than to morphine, the increased synthesis of M6G observed in IHU may prolong the narrow window of heroin effects.     

Effects of MDMA exposure on the conditioned place preference produced by other drugs of abuse

Rationale. MDMA is a serotonergic neurotoxin but few pre-clinical studies have found long-term behavioural consequences. As human users of MDMA are polydrug users, it is important to investigate whether the behavioural effects of other drugs are modulated by prior exposure to MDMA. Objectives. This study investigated whether pretreatment with a multiple high dose regimen of MDMA altered the rewarding effects of other drugs of abuse. Methods. Adult male Lister Hooded rats (n=10/group) were pretreated with 10 mg/kg MDMA or 1 ml/kg saline vehicle IP every 2 h for 6 h. Fourteen days later, conditioned place preference (CPP) to d-amphetamine (3 mg/kg), cocaine (20 mg/kg), ethanol (2.0 g/kg), heroin (0.5 mg/kg), or MDMA (10 mg/kg) was assessed. Results. In general, MDMA pretreatment had no effect on drug reward or habituation to the place conditioning apparatus. However, in contrast to saline pretreated rats, those animals receiving MDMA failed to show CPP after ethanol. Conclusion. MDMA pretreatment reduced the rewarding properties of ethanol. This finding may represent a functional consequence of MDMA-induced neurotoxicity. By extrapolation, human users of MDMA may be exposed to an increase in risks associated with alcohol abuse. Electronic Publication     

Similar enhancement of the discriminative stimulus effects of cocaine and GBR 12909 by heroin in squirrel monkeys

RATIONALE AND OBJECTIVES: Heroin previously was shown to engender partial cocaine-like discriminative stimulus (DS) effects in squirrel monkeys. The present study assessed the degree to which heroin modified the DS effects of cocaine and the cocaine-like DS effects of the selective dopamine transport blocker GBR 12909. METHODS AND RESULTS: In squirrel monkeys discriminating cocaine (0.3 mg/kg) from saline, cocaine and GBR 12909 dose-dependently engendered levels of responding on the cocaine-associated lever greater than or equal to 90% (full substitution). Heroin engendered full substitution for cocaine in two monkeys, partial substitution (75%) in a third monkey, and no substitution in the fourth monkey. When administered as a pretreatment, heroin shifted the dose-response function for cocaine to the left in the three monkeys for which heroin engendered cocaine-lever responding, but did not alter the DS effects of cocaine in the fourth monkey. Heroin pretreatment also shifted the dose-response function for the cocaine-like DS effects of GBR 12909 to the left in the former three monkeys, and did not alter the effects of GBR 12909 in the fourth monkey. Isobolographic analysis of the DS effects of cocaine-heroin and GBR 12909-heroin combinations in the former three monkeys revealed that the potencies of the combinations were not different from predicted values based on dose-additive effects. CONCLUSIONS: These findings show that heroin can enhance similarly the DS effects of cocaine and GBR 12909, suggesting that activation of dopaminergic systems underlies enhancement of the interoceptive effects of cocaine by heroin.     

Buprenorphine sublingual tablets: effects on IV heroin self-administration by humans

RATIONALE: Studies have shown that buprenorphine, a partial mu opioid agonist, effectively reduces heroin taking. While previous research with buprenorphine utilized a liquid formulation, a tablet formulation is proposed for clinical use. However, because recent research suggests that the liquid and tablet differ in bio-availability, it is unclear what dose of the buprenorphine tablet effectively antagonizes the reinforcing effects of heroin. OBJECTIVE: The present study was designed to compare the effects of two sublingual doses of buprenorphine maintenance on heroin self-administration. METHODS: Eight heroin-dependent men participated in a 6-week, double-blind, placebo-controlled inpatient study to evaluate the reinforcing effects of intravenous heroin (0, 6.25, 12.5, 25 mg) during maintenance on 8 or 16 mg sublingual buprenorphine. Participants first sampled the available dose of heroin, and then were allowed to respond under a progressive ratio schedule for either heroin or $20. For each heroin dose, one sample session and three choice sessions occurred. Two sessions per day were conducted. A sample session was followed by the first choice session on one day, and the second and third choice sessions occurred on the following day. These sessions were conducted while participants were maintained on daily doses of 8 or 16 mg buprenorphine (3 weeks each). RESULTS: Relative to placebo, 12.5 and 25 mg heroin produced significant increases in break point values under both maintenance dose conditions. The mean break point value for 12.5 mg heroin was significantly lower under 16 mg buprenorphine, compared to 8 mg. CONCLUSIONS: These results demonstrate that the reinforcing effects of heroin were not fully antagonized by these doses of the tablet formulation of buprenorphine, and that 16 mg buprenorphine reduced heroin self-administration relative to 8 mg.     

纳曲酮长效缓释剂包埋术100例临床分析

目的：验证纳洛酮冲击疗法、纳曲酮冲击疗法的临床效果,探讨纳曲酮长效缓释剂包埋术的防复吸效能。方法：需脱毒者采用NTX冲击疗法或NLX冲击疗法快速脱毒,次日进行NTX长效缓释剂包埋术,观察冲击疗法临床效果,随访出院后稽延性戒断症状及防复吸效能。结果：100例中,已完成脱毒者7例,采用NTX冲击治疗者36例,采用NLX冲击治疗者57例,次日进行包埋术,无一例出现严重戒断症状,冲击成功率100%,出现无菌性炎症4例,稽延性戒断症均在1个月以内消除,半年操守率96.8%。结论：NLX或NTX冲击疗法具有时间短、脱毒快、彻底、成功率高的优点,经得起临床验证。NTX长效缓释剂有较好的防复吸效能,很有临床实用价值。