Clinical review: Major consequences of illicit drug consumption

Effects of cocaine hydrolase on cocaine self-administration under a PR schedule and during extended access (escalation) in rats

RATIONALE AND OBJECTIVES

Previously, Albu-CocH, a cocaine hydrolase derived from human butyrylcholinesterase, blocked cocaine-induced reinstatement of drug seeking in rats. In the present study, rats were treated with Albu-CocH while self-administering cocaine under a progressive ratio (PR) schedule during 2-h sessions and under a fixed-ratio 1 (FR 1) schedule during 6-h sessions.

METHODS

In experiment 1, rats were treated with saline or Albu-CocH (2 or 4 mg/kg) before a single 2-h cocaine (0.2 mg/kg) self-administration (PR) session. In experiment 2, rats were treated with Albu-CocH or saline for the first seven of the 21-day 6-h sessions prior to cocaine (0.2 or 0.4 mg/kg) self-administration sessions (FR 1).

RESULTS

In experiment 1, Albu-CocH (vs saline) reduced cocaine infusions immediately following treatment compared with sessions pretreatment and posttreatment. In experiment 2, the Albu-CocH-treated groups (vs saline) showed an initial twofold to threefold increase in 0.2 and 0.4 mg/kg cocaine infusions over the 7 days of treatment, but they decreased to the infusion levels of saline controls by day 7. Cocaine (0.4 mg/kg) intake in the saline-treated group was elevated during the last 3 days of 6-h access compared with the first 3 days, indicating an escalation effect. Responding for 0.4 mg/kg (but not 0.2 mg/kg) cocaine during 2-h sessions after the 21 days of 6-h access was elevated in the saline groups (compared with 2-h sessions before long access) but not in the Albu-CocH-treated groups.

CONCLUSIONS

Albu-CocH decreased cocaine infusions under the PR schedule, indicating a reduced reward value of cocaine (experiment 1). However, Albu-CocH, compared with saline, temporarily increased cocaine infusions during long access. The post-long access 2-h cocaine intake was not increased in the Albu-CocH-treated groups as it was in the saline-treated groups. Albu-CocH is an effective agent for reducing cocaine reward under conditions of low cocaine exposure and chronic treatment.

Non-medical use of prescription drugs and sexual risk behavior in young adults

In recent years, the non-medical use of prescription drugs (without a doctor's prescription) has increased dramatically, particularly in young adults. Previous work has noted associations between the non-medical use of prescription drugs and the use of illicit drugs, and associations between the use of illicit drugs and sexual risk behavior. Investigations examining associations between the non-medical use of prescription drugs (NMUPD) and sexual risk behavior are sparse. In the present study, undergraduate students (n=435) ages 18-25 completed an instrument assessing these behaviors. Overall, 35.6% of participants reported NMUPD. Individuals who reported NMUPD were more likely to also report the use of alcohol, marijuana, ecstasy, cocaine, methamphetamine, and poppers. Participants who indicated they had used prescription medications without a doctor's consent had significantly higher rates of sexual risk behavior, including more sexual partners and more instances of unprotected sex in the previous 3 months. Results suggest that a significant minority of young adults are using prescription medication recreationally and are risking negative consequences, including the potential for addiction, dangerous interactions between prescription and recreational drugs, and greater risk for contracting sexually transmitted infections.

Comparative neuroscience of stimulant-induced memory dysfunction: role for neurogenesis in the adult hippocampus

The discovery that the addictive drugs impair neurogenesis in the adult hippocampus has prompted the elaboration of new biological hypotheses to explain addiction and drug-induced cognitive dysfunction. Considerable evidence now implicates the process of adult neurogenesis in at least some critical components of hippocampal-dependent memory function. In experimental models, psychomotor stimulant drugs produce alterations in the rate of birth, survival, maturation and functional integration of adult-born hippocampal neurons. Thus some of the deleterious consequences of drug abuse on memory could result from the neurotoxic actions of drugs on adult hippocampal neurogenesis. In this review, we will first summarize preclinical and clinical literature on the disruptive effects of drugs such as cocaine and ecstasy in the areas of learning, memory and attention. We will also summarize data that document the widespread effects of stimulant drugs on progenitor activity and precursor incorporation in the adult dentate gyrus. Finally, we will examine evidence that supports the involvement of hippocampal neurogenesis in specific aspects of learning and memory function and we will consider critically the hypothesis that some of the negative consequences of drug abuse on cognition might be ascribed to deficits in adult hippocampal neurogenesis. Evidence suggests that stimulant abuse impacts negatively on at least four areas of memory/cognitive function that may be influenced by adult hippocampal neurogenesis: contextual memory, spatial memory, working memory and cognitive flexibility.

Manejo do paciente com transtornos relacionados ao uso de substância psicoativa na emergência psiquiátrica

OBJETIVO: Transtornos por uso de substâncias são prevalentes em setores de emergência gerais e psiquiátricos, atingindo taxas de 28% das ocorrências em prontos-socorros gerais. Todavia, profissionais dos setores de emergência identificam menos que 50% dos casos de problemas relacionados ao álcool. Este artigo visa fornecer base fundamentada em evidências para o tratamento específico a pacientes que preencham os critérios diagnósticos de transtornos por uso de substâncias e que se apresentam ao pronto-socorro em quadros de intoxicação ou abstinência. MÉTODO: Uma revisão sobre o tema foi realizada na base de dados Medline, usando-se os descritores "intoxicação aguda", "abstinência", "álcool", "cocaína", "cannabis", "opioides", "inalantes" e "manejo", tendo o inglês como idioma. RESULTADOS E CONCLUSÃO: O cuidado de pessoas com transtornos por uso de substâncias deve conter: avaliação completa (médica geral e psiquiátrica), tratamento dos quadros diagnosticados (abstinência, intoxicação e quadros clínicos que caracterizem uma emergência), sensibilização do paciente para realizar tratamento, se for necessário, e elaboração de encaminhamento.

Effects of T-type calcium channel blockers on cocaine-induced hyperlocomotion and thalamocortical GABAergic abnormalities in mice

RATIONALE

Repetitive cocaine exposure has been shown to induce GABAergic thalamic alterations. Given the key role of T-type (Ca(V)3) calcium channels in thalamocortical physiology, the direct involvement of these calcium channels in cocaine-mediated effects needs to be further explored.

OBJECTIVE

The objective of this study was to investigate the effect of T-type calcium channel blockers on acute and repetitive cocaine administration that mediates thalamocortical alterations in mice using three different T-type blockers: 2-octanol, nickel, and mibefradil.

METHODS

During in vitro experiments, whole-cell patch-clamp recordings were conducted in ventrobasal (VB) thalamic neurons from mice treated with acute repetitive cocaine administration (3 x 15 mg/kg, i.p., 1 h apart), under bath application of mibefradil (10 μM), 2-octanol (50 μM), or nickel (200 μM). After systemic administration of T-type calcium channel blockers, we evaluated locomotor activity and also recorded GABAergic neurotransmission onto VB neurons in vitro.

RESULTS

Bath-applied mibefradil, 2-octanol, or nickel significantly reduced both GABAergic neurotransmission and T-type currents of VB neurons in cocaine-treated mice. In vivo i.p. pre-administration of either mibefradil (20 mg/kg and 5 mg/kg) or 2-octanol (0.5 mg/kg and 0.07 mg/kg) significantly reduced GABAergic mini frequencies onto VB neurons. Moreover, both mibefradil and 2-octanol were able to decrease cocaine-induced hyperlocomotion.

CONCLUSION

The results shown in this study strongly suggest that T-type calcium channels play a key role in cocaine-mediated GABAergic thalamocortical alterations, and further propose T-type channel blockers as potential targets for future pharmacological strategies aimed at treating cocaine's deleterious effects on physiology and behavior.

Agonist-like pharmacotherapy for stimulant dependence: preclinical, human laboratory, and clinical studies

A variety of natural and synthetic agents have long been used for stimulant properties, with nontherapeutic use producing multiple waves of stimulant abuse and dependence. The multitude of effects of stimulants exist on continua, and accordingly, here we characterize stimulant abuse/dependence and candidate pharmacotherapies in this manner. Behavioral therapy and medications have been investigated for treatment of stimulant abuse/dependence. Effectiveness of some behavioral interventions has been demonstrated. Most medications studied have been found to lack efficacy. However, an expanding literature supports use of agonist-like medications to treat stimulant abuse/dependence, a strategy effective for nicotine and opiate dependence. The agonist-like conceptualization for stimulant dependence posits that medications with properties similar to that of the abused drug, but possessing lesser abuse liability, will normalize neurochemistry and stabilize behavior, thus reducing drug use. Data suggest use of a range of medications, from l-dopa/carbidopa to amphetamine preparations, depending on the severity of use. This report reviews preclinical, human laboratory, and clinical trial data supporting the agonist-like approach, including risks and benefits. Future directions for development of agonist-like medications are also discussed.

Prevalence of mental disorders in primary care: results from the diagnosis and treatment of mental disorders in primary care study (DASMAP)

OBJECTIVE

Previous epidemiological studies have revealed a high prevalence of mental disorders among primary care (PC) patients. However, most studies have methodological limitations (e.g. absence of structured clinical interviews, two-phase designs) that affect the generalizability of their results. The main objective of the present study was to estimate the lifetime and 12-month prevalence of mental disorders in the PC of Catalonia (Spain), using structured clinical interviews and a one-phase design.

METHODS

One-phase cross-sectional survey. A representative probability sample without replacement of individuals aged 18 years or older attending PC for a medical visit were interviewed between October 2005 and March 2006. The interviews included SCID-I for depressive and anxiety disorders and the MINI interview for other mental disorders. A total of 3,815 patients from 77 PC centres were included in the statistical analyses.

RESULTS

45.1% of respondents reported at least one lifetime mental disorder and 30.2% reported at least one mental disorder in the previous 12 months. The most common mental disorders were major depression (9.6%), panic disorder (7.0%), specific phobia (6.6%), and generalized anxiety disorder (3.8%). There was a high comorbidity between mood and anxiety disorders, as well as between mental disorders and some chronic physical conditions.

CONCLUSIONS

There is a high prevalence and comorbidity of mental disorders in the PC of Catalonia. Public health policies should reinforce the role of family physicians in the detection and treatment of persons with mental disorders.

Management of injecting drug users admitted to hospital

General hospital clinicians frequently deal with injecting drug users because substance use has diverse medical and psychiatric complications. Non-specialist clinicians often initiate management when specialist consultation is not available or accepted by the patient. Here, we summarise evidence for the management of hospitalised injecting drug users. The first challenge is to engage a drug user into medical care. A non-judgmental approach towards patients and acceptance of their lifestyle choices facilitates engagement. Pragmatic clinical goals can be negotiated and achieved. We also describe common conditions of injecting drug users. Accurate diagnosis and appropriate management focus on common issues such as intoxication, withdrawal, pain management, drug seeking, psychological comorbidity, behavioural difficulties, and pregnancy. Effective management can reduce the medical and social effect of these conditions and is not difficult.

Effects of cocaine esterase following its repeated administration with cocaine in mice

BACKGROUND

A bacterial cocaine esterase (CocE) produces robust protection and reversal of cocaine toxicity. The aim of this study was to investigate how effectiveness of CocE was changed following its repeated administration together with cocaine.

METHODS

Cocaine toxicity was quantified by measuring the occurrence of convulsions and lethality in mice. Immunologic responses of CocE were determined using ELISA. In the protection experiment, i.v. CocE 0.3mg was given 1min before a lethal dose of i.p. cocaine 180mg/kg. In the rescue experiment, i.v. CocE 0.3mg was given 1min after the occurrence of convulsions elicited by i.p. cocaine 100mg/kg. In both treatment paradigms, four trials were conducted in the same animals with a 2-week interval.

RESULTS

CocE retained its effectiveness to protect or rescue mice during the first two trials and these mice did not show an immune response. In contrast, CocE's effectiveness was gradually reduced in the last two trials, accompanied by 10- and 100-fold increases in anti-CocE antibody titers. Nevertheless, effectiveness of CocE could be partially recovered by increasing the dose of CocE. In addition, escalating the dose of CocE from the minimum effective dose for repeated administration could also retain CocE's effectiveness longer and slow the production of anti-CocE antibodies.

CONCLUSIONS

These results indicate that CocE is a weak antigen and it can maintain its protective and rescuing ability initially against cocaine-induced toxicity. Decreased effectiveness of CocE following repeated use can be partially improved by adjusting the dose and frequency of CocE treatment.

The virtual gateway: opening doors in delirium teaching and learning

Delirium is a common, serious and potentially preventable problem. It is argued here that knowledge and skills for effective assessment and treatment of delirium cannot be considered 'specialist'. Rather, delirium is a problem that requires a healthcare team approach to assessing patients, identifying risks or symptoms and reducing precipitating factors. Research from the preceding decade suggests that the clinical reality is falling short of this ideal with the result that many cases of delirium go undetected and many precipitating factors are not reduced where this is indeed possible. This presents a challenge for the education of nursing and medical students and for the development of qualified staff in practice. The current paper outlines an educational approach, e-learning, which increases access for learners, integrates knowledge and skill development and promotes active, problem-based learning.