A study protocol for the N-ICE trial: A randomised double-blind placebo-controlled study of the safety and efficacy of N-acetyl-cysteine (NAC) as a pharmacotherapy for methamphetamine ("ice") dependence

How does a family history of psychosis influence the risk of methamphetamine-related psychotic symptoms: Evidence from longitudinal panel data

AIMS

To determine whether the risk of psychotic symptoms during weeks of methamphetamine use was dependent on, increased by, or independent of having a family history of psychosis.

DESIGN

Secondary analysis of 13 contiguous 1-week periods of data (1370 weeks). A risk modification framework was used to test each scenario.

SETTING

Geelong, Wollongong and Melbourne, Australia.

PARTICIPANTS

Participants in a randomized controlled trial of treatment for methamphetamine dependence (n = 148) who did not have a primary psychotic disorder on enrolment.

MEASUREMENTS

Psychotic symptoms in the previous week were defined as a score of 3+ on any of the Brief Psychiatric Rating Scale items of hallucinations, unusual thought content or suspiciousness. Any (vs no) methamphetamine use in the previous week was assessed using the Timeline Followback method. Self-reported family history of psychosis was assessed using the Diagnostic Interview for Psychosis.

FINDINGS

The risk of psychotic symptoms in the past week was independently associated with methamphetamine use in that week (relative risk [RR] = 2.3, 95% CI = 1.3-4.3) and with having a family history of psychosis (RR = 2.4, 95% CI = 0.9-7.0); the joint risk among participants with a family history of psychosis during weeks when they were using methamphetamine was large (RR = 4.0, 95% CI = 2.0-7.9). There was no significant interaction between a family history of psychosis and methamphetamine use in predicting psychotic symptoms (interaction RR = 0.7 95% CI = 0.3-1.8), but there was a small non-significant excess risk due to the interaction (0.20 95% CI = -1.63 to 2.03).

CONCLUSIONS

Among people dependent on methamphetamine, the relative risk of psychotic symptoms during weeks of methamphetamine use does not appear to be dependent on, or increased by, having a family history of psychosis. However, a family history of psychosis does appear to be an independent risk factor that contributes to the absolute risk of psychotic symptoms in this population.

Diagnostic accuracy for self-reported methamphetamine use versus oral fluid test as the reference standard in a methamphetamine-dependent intervention trial population

AIMS

Treatment of methamphetamine dependence requires monitoring of recent use or abstinence. Self-report is commonly used for routine monitoring, but the accuracy of self-report is not established. For the treating clinician, the key accuracy statistic is the negative predictive value (NPV). The study aim was to estimate the NPV of self-reported non-use of methamphetamine compared with an oral fluid reference standard.

DESIGN, SETTING AND PARTICIPANTS

This study was a secondary (subgroup) analysis from a randomized controlled pharmacotherapy trial. Three Australian outpatient addiction services took part. Particpants were 139 people dependent on methamphetamine.

MEASUREMENTS

Weekly oral fluid samples over 12 weeks to determine methamphetamine (and amphetamine) concentrations were used as the reference standard. Self-report of any methamphetamine use in the previous 7 days by the time-line follow-back method was the index test. Standard diagnostic accuracy statistics were calculated for all available paired episodes (n = 1134). Three NPV values were calculated: unadjusted NPV and NPV adjusted for clustering of observations through logistic regression and generalized estimating equation (GEE). We also calculated the NPVs for a range of prevalence rates of methamphetamine use, for the calculated levels of sensitivity and specificity.

FINDINGS

Sensitivity was 96.4% [95% confidence interval (CI) = 95-97.5], specificity was 63.7% (95% CI = 57.3-69.8) and positive predictive value (PPV) was 90.8% (95% CI = 88.8-92.6). The unadjusted NPV was 82.7% (95% CI = 76.5-87.9), adjusted NPV by logistic regression 82.7% (95% CI = 73.9-91.5) and GEE 76.8% (95% CI = 66.8-86.8). At a methamphetamine use prevalence of 5%, the estimated NPV would be 99.7% (95% CI = 99.6-99.9) and at 95% prevalence, 48.2% (95% CI = 39.6-57.0).

CONCLUSIONS

Self-report of no recent methamphetamine use appears to be sufficiently accurate to be clinically useful at the expected prevalence rates of methamphetamine use in clinical treatment settings. If generalizable to clinical settings, where these tests are routinely conducted, this may permit a reduction in the frequency and cost of oral fluid assays.

N-acetyl cysteine in the treatment of cannabis use disorder: A systematic review of clinical trials

BACKGROUND AND AIM

Cannabis is the most consumed illicit drug globally, with a high risk of developing cannabis use disorder (CUD). No approved pharmacological treatment exists for CUD, but N-Acetyl Cysteine (NAC) has shown promising results in different clinical studies. This study aims to conduct a systematic review of NAC clinical trials for the treatment of CUD.

METHODS

Systematic review of randomized controlled trials (RCTs) was conducted to determine the effect of NAC for the treatment of cannabis dependence/cannabis use disorder (CUD). Articles were electronically searched across different databases using PubMed, Google Scholar, EMBASE, Cochrane Library, Medline and PsycINFO from inception to June 2021. Several study characteristics, including study duration, sample size, study population and age group, intervention, adverse effects, and outcome measure were extracted. A PICO table was used for data extraction.

RESULTS

We included 08 RCTs in the qualitative analysis. The risk of bias (RoB) was assessed according to Cochrane RoB criteria, and a 5 point grading system according to the Oxford Centre for Evidence-Based Medicine was used to rate the methodological quality (level of evidence) of the included articles. Mild and well-tolerated adverse events were reported in the placebo and NAC group.

CONCLUSIONS

The studies collectively offer mixed results, although the strength of the evidence available on which to make a recommendation is strong. NAC has shown to be effective in promoting abstinence, medication adherence and reducing cannabis use and craving among cannabis dependent users. This review also suggests recommendations for future research.

N-acetylcysteine (NAC) for methamphetamine dependence: A randomised controlled trial

BACKGROUND

Methamphetamine dependence is a significant global health concern for which there are no approved medications. The cysteine prodrug, N-acetylcysteine (NAC), has been found to ameliorate glutamate dysregulation in addiction, and to reduce craving for methamphetamine and other drugs. We evaluated the efficacy and safety of NAC as a pharmacotherapy for methamphetamine dependence.

METHODS

A parallel double-blind randomised placebo-controlled trial of people dependent on methamphetamine recruited from Geelong, Melbourne and Wollongong, Australia, between July 2018 and December 2019. Participants were randomised to receive either 12 weeks of oral NAC (2400 mg/day) or matched placebo, delivered as a take-home medication. The primary outcome was methamphetamine use, measured in two ways: (a) change in days of use in the past 4 weeks from baseline to weeks 4, 8 and 12, assessed using the Timeline Followback; and (b) methamphetamine-positive oral fluid samples taken weekly. Analyses were intention-to-treat and based on imputed data. Secondary outcomes were craving, severity of dependence, withdrawal severity and psychiatric symptoms (depression, suicidality, hostility and psychotic symptoms). Significance levels were p < 0.025 for primary outcomes and p < 0.01 for secondary outcomes. Adverse events were compared between groups by system organ class. The study was prospectively registered, ACTRN12618000366257.

RESULTS

Participants (N = 153; 59% male, mean [SD] age 38 [8]) were randomised to placebo (n = 77) or NAC (n = 76). Both groups had a median (IQR) of 24 (15-28) days of methamphetamine use in the 4 weeks prior to baseline. Both groups significantly reduced methamphetamine use (mean [SE] reduction of 7.3 [1.2]) days for placebo, 6.8 [1.2] for NAC) but NAC did not reduce days of methamphetamine use more than placebo (group difference of 0.5 days, 97.5% CI -3.4-4.3). There was no significant effect of NAC on methamphetamine-positive oral fluid samples (placebo 79%, NAC 76%; mean difference -2.6, 97.5% CI -12.6-7.4). NAC did not significantly reduce craving, severity of dependence, withdrawal, suicidality, depression, hostility or psychotic symptoms relative to placebo. Adverse events did not differ significantly between placebo and NAC groups.

INTERPRETATION

These findings suggest that take-home oral NAC has no significant effect on methamphetamine use or most clinically related outcomes amongst people who are dependent on the drug.

Behavioural and biochemical responses to methamphetamine are differentially regulated by mGlu2 and mGlu3 metabotropic glutamate receptors in male mice

Group II metabotropic glutamate receptors (mGlu2 and mGlu3 receptors) shape mechanisms of methamphetamine addiction, but the individual role played by the two subtypes is unclear. We measured methamphetamine-induced conditioned place preference (CPP) and motor responses to single or repeated injections of methamphetamine in wild-type, mGlu2^-/-, and mGlu3^-/-mice. Only mGlu3^-/-mice showed methamphetamine preference in the CPP test. Motor response to the first methamphetamine injection was dramatically reduced in mGlu2^-/-mice, unless these mice were treated with the mGlu5 receptor antagonist, MTEP. In contrast, methamphetamine-induced sensitization was increased in mGlu3^-/-mice compared to wild-type mice. Only mGlu3^-/-mice sensitized to methamphetamine showed increases in phospho-ERK1/2 levels in the nucleus accumbens (NAc) and free radical formation in the NAc and medial prefrontal cortex. These changes were not detected in mGlu2^-/-mice. We also measured a series of biochemical parameters related to the mechanism of action of methamphetamine in naïve mice to disclose the nature of the differential behavioural responses of the three genotypes. We found a reduced expression and activity of dopamine transporter (DAT) and vesicular monoamine transporter-2 in the NAc and striatum of mGlu2^-/-and mGlu3^-/-mice, whereas expression of the DAT adaptor, syntaxin 1A, was selectively increased in the striatum of mGlu3^-/-mice. Methamphetamine-stimulated dopamine release in striatal slices was largely reduced in mGlu2^-/-, but not in mGlu3^-/-, mice. These findings suggest that drugs that selectively enhance mGlu3 receptor activity or negatively modulate mGlu2 receptors might be beneficial in the treatment of methamphetamine addiction and associated brain damage.

Cognitive insight, medication adherence and methamphetamine cessation in people enrolled in a pharmacotherapy trial for methamphetamine use

BACKGROUND

The current study examined correlates of cognitive insight in people enrolled in a methamphetamine pharmacotherapy trial; whether cognitive insight at the start of the trial predicted medication adherence and reductions in methamphetamine use during the trial; and, whether insight would remain stable over the trial or improve with reductions in methamphetamine use.

METHODS

A subset of people enrolled in a 12-week randomised placebo-controlled pharmacotherapy trial for methamphetamine dependence completed the Beck Cognitive Insight Scale, comprising subscales for Self-Reflection and Self-Certainty, at baseline (n = 152) and at week 12 (n = 79). Medication adherence was expressed as the percentage of non-missed doses measured using eCAP™ technology. Methamphetamine use days were assessed using the Timeline Followback.

RESULTS

At baseline, greater Self-Reflection was correlated with more severe methamphetamine withdrawal, and hostility, whereas Self-Certainty was correlated with less education and longer duration of methamphetamine use. No relationship was found between BCIS subscales at baseline and medication adherence (Self-Reflection b[SE] = -0.73 [0.43] p = .09; Self-Certainty b[SE] = -0.31 [0.48] p = .52,). Neither BCIS subscale was predictive of reduced methamphetamine use at 12 weeks (Self-Reflection b[SE] = 0.001 [0.01] p = .95 Self-Certainty b[SE] = -0.003 [0.01], p = .74). Self-Reflection decreased over the trial (t = 3.42, p = .001) but this was unrelated to change in methamphetamine use (Self-Reflection, b[SE] = -1.68 [1.16] p = .15) Change in methamphetamine use was found to be a significant predictor of Self-Certainty at 12 weeks (b [SE] = -2.71 [1.16] p = .02).

CONCLUSIONS

We found no evidence that cognitive insight predicted medication adherence or methamphetamine reduction in people engaged in this trial. Ongoing or increased methamphetamine use predicted increased Self-Certainty at 12 weeks.

Hepatitis C treatment in a co-located mental health and alcohol and drug service using a nurse-led model of care

Hepatitis C virus (HCV) is more prevalent among people with experience of severe mental illness compared to the general population, due in part to higher levels of injecting drug use. Delivering HCV care through mental health services may reduce barriers to care and improve outcomes. A nurse-led HCV program was established in a co-located mental health and addiction service in Melbourne, Australia. People with a history of injecting drug use, including current use, were referred for HCV testing by nurses, with support provided on-site from a general practitioner and remotely from infectious disease and hepatology specialists. A nurse practitioner, general practitioner or specialists were able to prescribe HCV treatment. One-hundred and thirty people were referred to the nurse-led service, among whom 112 (86%) were engaged in care. Of those 112, 84 (75%) were found to have detectable HCV RNA, 70 (83%) commenced treatment; 28 (40%) prescriptions were nurse initiated, 19 (27%) were general practitioner initiated and 20 (29%) were prescribed from hospital clinics or elsewhere. All people with an SVR result (48/70) achieved HCV cure (intention to treat SVR 69%, per-protocol SVR 100%). Treatment commencement was highest among people prescribed opioid agonist therapy (28/29, 96%) compared to those who were not (18/26, 69%). In conclusion, a nurse-led, HCV service for people with severe mental illness including pathways to specialist support when needed can achieve high treatment uptake and cure. Further implementation work is required to improve treatment uptake, particularly among people not prescribed opioid agonist therapy, and to improve follow-up for SVR testing.

The Multifaceted Therapeutic Role of N-Acetylcysteine (NAC) in Disorders Characterized by Oxidative Stress

Oxidative stress, which results in the damage of diverse biological molecules, is a ubiquitous cellular process implicated in the etiology of many illnesses. The sulfhydryl-containing tripeptide glutathione (GSH), which is synthesized and maintained at high concentrations in all cells, is one of the mechanisms by which cells protect themselves from oxidative stress. N-acetylcysteine (NAC), a synthetic derivative of the endogenous amino acid L-cysteine and a precursor of GSH, has been used for several decades as a mucolytic and as an antidote to acetaminophen (paracetamol) poisoning. As a mucolytic, NAC breaks the disulfide bonds of heavily cross-linked mucins, thereby reducing mucus viscosity. In vitro, NAC has antifibrotic effects on lung fibroblasts. As an antidote to acetaminophen poisoning, NAC restores the hepatic GSH pool depleted in the drug detoxification process. More recently, improved knowledge of the mechanisms by which NAC acts has expanded its clinical applications. In particular, the discovery that NAC can modulate the homeostasis of glutamate has prompted studies of NAC in neuropsychiatric diseases characterized by impaired glutamate homeostasis. This narrative review provides an overview of the most relevant and recent evidence on the clinical application of NAC, with a focus on respiratory diseases, acetaminophen poisoning, disorders of the central nervous system (chronic neuropathic pain, depression, schizophrenia, bipolar disorder, and addiction), cardiovascular disease, contrast-induced nephropathy, and ophthalmology (retinitis pigmentosa).

Complications Related to Sexualized Drug Use: What Can We Learn From Literature?

Chemsex is described as the use of specific psychoactive substances (PS) during sexual activity to sustain, enhance, disinhibit or facilitate the sexual experience. It preferentially concerns men who have sex with men (MSM). They use new synthetic substances like cathinones, methamphetamines, gamma-butyrolactone/gamma-hydroxybutyrate (GBL/GHB), ketamine, and cocaine. The prevalence of chemsex varies from 3 to 31% during lifetime. The Internet has participated significantly in the evolution of sexual behaviors, both in terms of sexual dating and the availability of new synthetic substances. The advent of geolocation applications contributed to the development of chemsex. The literature describes many complications linked to these sexual practices; the main clinical effects related to cathinones consumption were psychiatric symptoms; agitation, hallucinations, anxiety, suicidal ideation, paranoia, and confusion. Regular GBL/GHB consumption alter cognitive functions, particularly memory and emotion management. Use of these drugs in party and play is dramatically associated with high-risk sexual behaviors. The prevalence of hepatitis B, hepatitis C syphilis, and HIV is higher in men who use methamphetamine and Viagra and/or who declared they practiced slamming, chemsex, and fisting. Other sexually transmitted infections (STIs) such as gonorrhea have increased with methamphetamine and GHB/GBL use. Actually, the care of individuals who practice Chemsex in a problematic way is currently not codified, but the use of integrative and specific interventions is necessary.

Clinical and demographic characteristics of people who smoke versus inject crystalline methamphetamine in Australia: Findings from a pharmacotherapy trial

INTRODUCTION AND AIMS

There has been a rapid increase in smoking crystalline methamphetamine in Australia. We compare the clinical and demographic characteristics of those who smoke versus inject the drug in a cohort of people who use methamphetamine.

DESIGN AND METHODS

Participants (N = 151) were dependent on methamphetamine, aged 18-60 years, enrolled in a pharmacotherapy trial for methamphetamine dependence, and reported either injecting (n = 54) or smoking (n = 97) methamphetamine. Measures included the Timeline Followback, Severity of Dependence Scale, Amphetamine Withdrawal Questionnaire, Craving Experience Questionnaire and the Brief Psychiatric Rating Scale (symptoms of depression, hostility, psychosis and suicidality). Simultaneous regression was used to identify independent demographic correlates of smoking methamphetamine and to compare the clinical characteristics of participants who smoked versus injected.

RESULTS

Compared to participants who injected methamphetamine, those who smoked methamphetamine were younger and less likely to be unemployed, have a prison history or live alone. Participants who smoked methamphetamine used methamphetamine on more days in the past 4 weeks than participants who injected methamphetamine (26 vs. 19 days, P = 0.001); they did not differ significantly in their severity of methamphetamine dependence, withdrawal, craving or psychiatric symptoms (P > 0.05). After adjustment for demographic differences, participants who smoked had lower craving [b (SE) = -1.1 (0.5), P = 0.021] and were less likely to report psychotic symptoms [b (SE) = -1.8 (0.7), P = 0.013] or antidepressant use [b (SE) = -1.1 (0.5), P = 0.022].

DISCUSSION AND CONCLUSIONS

Smoking crystalline methamphetamine is associated with a younger less marginalised demographic profile than injecting methamphetamine, but a similarly severe clinical profile.

Pharmacological Treatment of Methamphetamine/Amphetamine Dependence: A Systematic Review

BACKGROUND

Stimulant drugs are second only to cannabis as the most widely used class of illicit drug globally, accounting for 68 million past-year consumers. Dependence on amphetamines (AMPH) or methamphetamine (MA) is a growing global concern. Yet, there is no established pharmacotherapy for AMPH/MA dependence. A comprehensive assessment of the research literature on pharmacotherapy for AMPH/MA dependence may inform treatment guidelines and future research directions.

METHODS

We systematically reviewed the peer-reviewed literature via the electronic databases PubMed, EMBASE, CINAHL and SCOPUS for randomised controlled trials reported in the English language examining a pharmacological treatment for AMPH/MA dependence or use disorder. We included all studies published to 19 June 2019. The selected studies were evaluated for design; methodology; inclusion and exclusion criteria; sample size; pharmacological and (if included) psychosocial interventions; length of follow-up and follow-up schedules; outcome variables and measures; results; overall conclusions and risk of bias. Outcome measures were any reported impact of treatment related to AMPH/MA use.

RESULTS

Our search returned 43 studies that met our criteria, collectively enrolling 4065 participants and reporting on 23 individual pharmacotherapies, alone or in combination. Disparate outcomes and measures (n = 55 for the primary outcomes) across studies did not allow for meta-analyses. Some studies demonstrated mixed or weak positive signals (often in defined populations, e.g. men who have sex with men), with some variation in efficacy signals dependent on baseline frequency of AMPH/MA use. The most consistent positive findings have been demonstrated with stimulant agonist treatment (dexamphetamine and methylphenidate), naltrexone and topiramate. Less consistent benefits have been shown with the antidepressants bupropion and mirtazapine, the glutamatergic agent riluzole and the corticotropin releasing factor (CRF-1) antagonist pexacerfont; whilst in general, antidepressant medications (e.g. selective serotonin reuptake inhibitors [SSRIs], tricyclic antidepressants [TCAs]) have not been effective in reducing AMPH/MA use.

CONCLUSIONS

No pharmacotherapy yielded convincing results for the treatment of AMPH/MA dependence; mostly studies were underpowered and had low treatment completion rates. However, there were positive signals from several agents that warrant further investigation in larger scale studies; agonist therapies show promise. Common outcome measures should include change in use days. Future research must address the heterogeneity of AMPH/MA dependence (e.g. coexisting conditions, severity of disorder, differences between MA and AMPH dependence) and the role of psychosocial intervention.