Patterns of polydrug use among ketamine injectors in New York City

Recreational Ketamine Use among Individuals with Opioid Use Disorder: Demographics, Motivations, and Polysubstance Use

BACKGROUND

Data show that recreational ketamine use appears to be increasing. This study aimed to understand how ketamine fits into broader polysubstance use in individuals with opioid use disorder (OUD).

METHODS

Survey data were collected from a sample of treatment-seeking individuals with OUD in March 2022.

RESULTS

Of 301 respondents, 28.6% reported lifetime ketamine use. Ketamine use was more frequently reported among males (61.9% vs. 37%; p < 0.001) and less frequently reported among individuals in rural locations (33.6% vs 15.7%; p < 0.002). Most respondents (70.9%) used ketamine to achieve a desired psychoactive effect, and 46.4% used to self-treat a physical or mental health problem, including mental distress symptoms and mitigating opioid withdrawal symptoms or cravings. Polysubstance use involving ketamine was prevalent (70.7%) and included marijuana (64.9%), alcohol (61.4%), cocaine (36.8%), MDMA (36.8%), hallucinogens (31.6%), prescription opioids (29.8%), and illicit opioids (29.8%). Negative experiences while using ketamine were reported by 32.1% and included central nervous system complications and mental distress.

CONCLUSIONS

Among this sample of individuals with OUD, motivations for ketamine use are varied and polysubstance use is common. Such behaviors, even when attempting to self-treat OUD or other health problems may place individuals at risk for psychiatric or physical health conditions, including overdose or death.

Trends and characteristics in ketamine use among US adults with and without depression, 2015-2022

BACKGROUND

Ketamine's potential for treating depression has drawn increased clinical interest in recent years. However, despite growing therapeutic use, recreational use among individuals with depression remain underexplored.

METHODS

We analyzed data from the 2015-2022 National Survey on Drug Use and Health focusing on adults in the US. Trends in past-year ketamine use, overall and by depression status, were estimated separately for 2015-2019 and 2021-2022 due to methodological changes in the survey. We also delineated correlates of ketamine use in each period, focusing on depression, sociodemographic characteristics, and other past-year drug use.

RESULTS

Overall ketamine use prevalence increased from 2015 to 2019 (from 0.11 % to 0.20 %, an 81.8 % increase, p < 0.01) and from 2021 to 2022 (from 0.20 % to 0.28 %, a 40.0 % increase, p < 0.05). From 2015 to 2019, use increased among adults with and without depression (by 139.3 % [p < 0.05] and 66.7 % [p < 0.05], respectively), while from 2021 to 2022, an increase occurred only among those without depression (by 38.9 %, p < 0.05). Multivariable models revealed that depression was associated with increased odds of ketamine use in 2015-2019 (aOR = 1.80, 95 % CI: 1.12-2.89) but not in later years. New sociodemographic correlates emerged in 2021-2022, including adults aged 26-34 and those with a college degree being at higher odds for use. Various drugs (especially ecstasy/MDMA and gamma-hydroxybutyrate) were consistently associated with higher odds of use.

CONCLUSION

We identified differential patterns and correlates of ketamine use over time. Shifts may be related to the evolving ketamine landscape and/or changing survey methodology. Monitoring of use patterns is crucial to inform prevention and harm reduction strategies.

The effects of ketamine and methamphetamine on neurotransmitters, glutamate receptors, and conditioned place preference in rat

Combined methamphetamine (MA) and ketamine (KET) abuse is a serious issue. At present, however, few studies have explored the mechanism underlying their combined addiction. We established a rat conditioned place preference (CPP) model. We investigated the role of dopamine (DA), 5-hydroxytryptamine (5-HT), monoamine oxidase (MAO), glutamate receptor 1 (GluR1), and glutamate receptor 2 (GluR2) in combined MA and KET addiction. The expression levels of DA, 5-HT, and MAO were detected by enzyme-linked immunosorbent assay (ELISA), and the expressions levels of GluR1 and GluR2 were detected by western blotting. Our results showed that MA and KET successfully induced CPP in rats respectively, and KET enhanced MA-induced CPP effects, although not significantly, and KET can reduce the MA-induced increase in DA, 5-HT, MAO and promoted the MA-induced increase in GluR1 and GluR2. Therefore, it suggested that DA, 5-HT, MAO, GluR1, and GluR2 expression may be involved in the mechanism underlying MA and KET-induced drug addiction in rats. Moreover, When MA and KET are used in combination, KET appears to play a dual addictive and anti-addictive role in the regulation of MA addiction.

Occurrence of Z-drugs, benzodiazepines, and ketamine in wastewater in the United States and Mexico during the Covid-19 pandemic

Z-drugs, benzodiazepines and ketamine are classes of psychotropic drugs prescribed for treating anxiety, sleep disorders and depression with known side effects including an elevated risk of addiction and substance misuse. These drugs have a strong potential for misuse, which has escalated over the years and was hypothesized here to have been exacerbated during the COVID-19 pandemic. Wastewater-based epidemiology (WBE) constitutes a fast, easy, and relatively inexpensive approach to epidemiological surveys for understanding the incidence and frequency of uses of these drugs. In this study, we analyzed wastewater (n = 376) from 50 cities across the United States and Mexico from July to October 2020 to estimate drug use rates during a pandemic event. Both time and flow proportional composite and grab samples of untreated municipal wastewater were analyzed using solid-phase extraction followed by liquid chromatography-tandem mass spectrometry to determine loadings of alprazolam, clonazepam, diazepam, ketamine, lorazepam, nordiazepam, temazepam, zolpidem, and zaleplon in raw wastewater. Simultaneously, prescription data of the aforementioned drugs were extracted from the Medicaid database from 2019 to 2021. Results showed high detection frequencies of ketamine (90 %), lorazepam (87 %), clonazepam (76 %) and temazepam (73 %) across both Mexico and United States and comparatively lower detection frequencies for zaleplon (22 %), zolpidem (9 %), nordiazepam (<1 %), diazepam (<1 %), and alprazolam (<1 %) during the pandemic. Average mass consumption rates, estimated using WBE and reported in units of mg/day/1000 persons, ranged between 62 (temazepam) and 1100 (clonazepam) in the United States. Results obtained from the Medicaid database also showed a significant change (p < 0.05) in the prescription volume between the first quarter of 2019 (before the pandemic) and the first quarter of 2021 (pandemic event) for alprazolam, clonazepam and lorazepam. Study results include the first detections of zaleplon and zolpidem in wastewater from North America.

Overdoses and deaths related to the use of ketamine and its analogues: a systematic review

Background: Although the misuse of ketamine constitutes a worldwide issue, ketamine is quickly taking its place as a therapeutic option in the management of several mental disorders. However, the use of ketamine and/or its analogues, as well as combinations with other drugs, can be fatal.Objective: To outline the cases of overdoses and deaths related to the use of ketamine and/or its analogues, as reported in the scientific literature. To investigate if ketamine is safe in a therapeutic context, particularly in its use as an antidepressant.Methods: Electronic searches were performed on three medical databases. Articles describing cases of overdose and/or death associated with ketamine and/or its analogues were included. After the removal of duplicates, title analysis and full-text analysis, 34 articles were included in this review.Results: Eighteen articles described fatal cases and sixteen described overdoses. Poly-substance use was mentioned in 53% of the selected articles. Most cases were males and the ages varied from two to 65 years old. A total of 312 overdose cases and 138 deaths were reported. In both death reports and overdose cases, ketamine was preponderant: 89.1% and 79%, respectively. No cases of overdose or death related to the use of ketamine as an antidepressant in a therapeutic setting were found; most of the deaths occurred in the circumstances of polydrug use and overdoses left no sequelae.Conclusion: There is legitimate concern about the risks involving the use of ketamine and its analogues, especially in recreational settings. On the other hand, ketamine as medicine is considered safe and it is listed as an essential medicine by the World Health Organization. Although clinicians must remain vigilant, this should not deter appropriate prescription.

Clinical and behavior characteristics of individuals who used ketamine

This study aims to depict and compare clinical characteristics and risk behavior among groups of individuals using ketamine, polydrugs or smoking cigarette. A total of 185 drug-using participants and 49 smokers participated in this study. A cross-sectional interview was used to collect information on demographics, drug- and sex-related behaviors, HIV serostatus, lower urinary tract symptoms (LUTS), behavioral dispositions. N-back memory test was used to measure short-term memory. Result shows that 10 participants (5.41%) were HIV positive and 14 (7.57%) having LUTS. Individuals with ketamine and polydrugs use have significantly worse drug-related problem than cigarette smokers. Compared to cigarette smokers and ketamine users, individuals with polydrug users scored significantly higher on impulsivity measures. Cigarette smokers performed significantly better than the other two groups on the memory tests. A few patients had been infected with HIV and diagnosed with LUTS. Findings support that memory on short term recalls of patients with ketamine use might be impaired. Study findings warrants the necessarily of further study on influences of using ketamine.

Causes and Consequences of Drug Abuse: A Comparison Between Synthetic Drug and Heroin Users in Urban China

This article examined the differences in causes and health consequences between synthetic drug and heroin abuse in urban China. Two-group comparisons were conducted to quantify differences in individual characteristics, causes of drug use, and HIV/STI risky sexual behavior between synthetic drug and heroin users; logistic regressions were employed to assess the net effect of synthetic drug use on risky sexual behavior. Results revealed that causes of synthetic drug use differed from those of heroin use; a combination of the knowledge gap concerning the harmful impact of synthetic drugs and the lesser punishment for their use appeared a main reason behind the shift from heroin to synthetic drugs; and synthetic drug use was a significant and powerful risk factor for HIV/STI risky sexual behavior. Educational and behavioral interventions are urgently needed to prevent the initiation of synthetic drug use among users to reduce their HIV/STI risky sexual behavior.

Potential Risks of Ecological Momentary Assessment Among Persons Who Inject Drugs

BACKGROUND

Ecological momentary assessment (EMA)-which often involves brief surveys delivered via mobile technology-has transformed our understanding of the individual and contextual micro-processes associated with legal and illicit drug use. However, little empirical research has focused on participant's perspective on the probability and magnitude of potential risks in EMA studies.

OBJECTIVES

To garner participant perspectives on potential risks common to EMA studies of illicit drug use.

METHODS

We interviewed 38 persons who inject drugs living in San Diego (CA) and Philadelphia (PA), United States. They completed simulations of an EMA tool and then underwent a semi-structured interview that systematically explored domains of risk considered within the proposed revisions to the Federal Policy for the Protection of Human Subjects or the "Common Rule." Interviews were transcribed verbatim and coded systematically to explore psychological, physical, social, legal, and informational risks from participation.

RESULTS

Participants perceived most risks to be minimal. Some indicated that repetitive questioning about mood or drug use could cause psychological (i.e., anxiety) or behavioral risks (i.e., drug use relapse). Ironically, the questions that were viewed as risky were considered motivational to engage in healthy behaviors. The most cited risks were legal and social risks stemming from participant concerns about data collection and security.

IMPORTANCE

Improving our understanding of these issues is an essential first step to protect human participants in future EMA research. We provide a brief set of recommendations that can aid in the design and ethics review of the future EMA protocol with substance using populations.

Concurrent polysubstance use in a longitudinal study of US youth: associations with sexual orientation

AIMS

To estimate longitudinal associations between self-reported sexual orientation and past-year polysubstance use among youth, and test how gender, age and early onset of tobacco and alcohol use contributed to variation in polysubstance use.

DESIGN

Longitudinal community-based cohort of US adolescents from the Growing Up Today Study (GUTS 1) (n = 16 873) followed from ages 12-29 years.

SETTING

United States of America.

PARTICIPANTS

A total of 13 519 individuals (7839 females; 5680 males) who responded to at least one of five self-administered questionnaires from 1999 to 2010. Ninety-three per cent reported their race/ethnicity as non-Hispanic white.

MEASUREMENTS

Multivariable repeated measures generalized estimating equations estimated relative risks (RRs) of concurrent polysubstance use (i.e. past 12-month use of three or more substances) comparing sexual orientation minority youth [i.e. mostly heterosexual (MH), bisexual (BI), gay/lesbian (GL)] to their same-gender, completely heterosexual (CH) counterparts. Mediation analyses tested whether early onset of tobacco and/or alcohol use explained relationships between sexual orientation and concurrent polysubstance use.

FINDINGS

Compared with their same-gender CH peers, sexual minorities evidenced higher risk for concurrent polysubstance use over all repeated measures [risk ratios (RRs) for sexual minority subgroups: from 1.63-2.91, P-values: <0.001] and for all age groups (RRs: from 1.50-4.04, P-values: < 0.05-< 0.001), except GL males aged 18-20 years. Differences between sexual minorities and CHs were larger among females than males (P-values for sexual orientation × gender interactions were < 0.05 for MHs and BIs), and among younger versus older ages (P-values for sexual orientation × age interactions were < 0.05, except for BI males). Sexual minorities' younger age of smoking and/or drinking initiation contributed to their elevated polysubstance use (% of effect explained was between 9.4-24.3, P-values: 0.04-< 0.001), except among GL males.

CONCLUSIONS

Sexual minority youth in the United States, and in particular younger females, appear to be at disproportionate risk for concurrent past-year polysubstance use. Early onset of smoking and drinking may contribute to elevated risk of polysubstance use among sexual minorities.

Prevalence and Patterns of Prescription Drug Misuse among Young Ketamine Injectors

In recent years, epidemiological monitoring data has indicated sharp increases in prescription drug misuse. Despite these increases, little is known about the context or patterns associated with prescription drug misuse, particularly among youth or young injection drug users (IDUs). A three-city study of 213 young IDUs found prescription drug misuse to be pervasive, specifically the use of opioids and benzodiazepines. Particular practices not commonly associated with prescription drugs were reported, such as sniffing, smoking, and injection. Associated health risks included initiation into injection drug use, polydrug use, drug overdose, and drug dependency. A greater awareness of the potential health risks associated with prescription drug misuse should be incorporated into services that target IDUs, including street outreach, syringe exchanges, and drug treatment.

Patterns of drug use, risky behavior, and health status among persons who inject drugs living in San Diego, California: a latent class analysis

BACKGROUND

Among persons who inject drugs (PWID), polydrug use (the practice of mixing multiple drugs/alcohol sequentially or simultaneously) increases risk for HIV transmission and unintentional overdose deaths. Research has shown local drug markets influence drug use practices. However, little is known about the impact of drug mixing in markets dominated by black tar heroin and methamphetamine, such as the western United States.

METHODS

Data were collected through an ongoing longitudinal study examining drug use, risk behavior, and health status among PWID. Latent class analysis (LCA) was used to identify patterns of substance use (heroin, methamphetamine, prescription drugs, alcohol, and marijuana) via multiple administration routes (injecting, smoking, and swallowing). Logistic regression was used to identify behaviors and health indicators associated with drug use class.

RESULTS

The sample included 511 mostly white (51.5%) males (73.8%), with mean age of 43.5 years. Two distinct classes of drug users predominated: methamphetamine by multiple routes (51%) and heroin by injection (49%). In multivariable logistic regression, class membership was associated with age, race, and housing status. PWID who were HIV-seropositive and reported prior sexually transmitted infections had increased odds of belonging to the methamphetamine class. Those who were HCV positive and reported previous opioid overdose had an increased odds of being in the primarily heroin injection class (all P-values < .05).

CONCLUSION

Risk behaviors and health outcomes differed between PWID who primarily inject heroin vs. those who use methamphetamine. The findings suggest that in a region where PWID mainly use black tar heroin or methamphetamine, interventions tailored to sub-populations of PWID could improve effectiveness.

Associations between prescription opioid injection and Hepatitis C virus among young injection drug users

OBJECTIVE

Hepatitis C virus (HCV) incidence has been increasing among young injection drug users (IDUs). This analysis examined whether the emerging practice of prescription opioid (PO) injection is associated with self-reported HCV among young IDUs.

METHODS

Young IDUs (n = 162) aged 18-25-years-old who indicated recent misuse of prescription drugs were sampled in New York and Los Angeles during 2009-2011. Participants reported lifetime PO injection history and results from their most recent HCV test as well as demographic characteristics and lifetime drug use. Bivariate analyses examined relationships between covariates and both lifetime PO injection and HCV positivity. Poisson regression examined the associations between lifetime PO injection, HCV positivity, and significant covariates.

RESULTS

A majority reported lifetime PO injection (72.2%) and 30.9% self-reported being HCV positive. Lifetime PO injectors were nearly three times more likely to report being HCV positive than non-PO injectors (adjusted incidence rate ratio (AIRR): 2.69, p<0.05) after controlling for socio-demographic and other drug use variable. Additionally, substituting POs for heroin (AIRR: 2.27, p<0.05), growing up in a lower social class (AIRR: 1.67, p<0.05), age (AIRR: 1.12, p<0.05), age of injection initiation (AIRR: 0.87, p<0.001), and history of being prescribed stimulants (AIRR: 0.64, p<0.05) were independently associated with HCV positivity.

CONCLUSIONS

Findings suggest that PO injection should be given further consideration as a contributing factor to rising HCV infection among young adults in the US.

A typology of prescription drug misuse: a latent class approach to differences and harms

INTRODUCTION AND AIMS

Prescription drug misuse is a considerable problem among young adults, and the identification of types of misuse among this population remains important for prevention and intervention efforts. We use latent class analysis to identify possible distinct latent groups of prescription drug misusers across multiple prescription drug types (pain killers, sedatives and stimulants).

DESIGN AND METHODS

Our data are comprised of a sample of 404 young adults recruited from nightlife scenes via time-space sampling. Through the specification of a zero-inflated Poisson latent class analysis, we evaluate differences in class membership by various demographic factors as well as assess the relationship between class membership and health outcomes, including indications of dependence, problems associated with substance use and mental health.

RESULTS

Our assessment of fit indices led to a four-class solution (dabblers, primary stimulant users, primary downers users and extensive regulars). No demographic differences existed between latent classes. The extensive regular class report the greatest number of symptoms related to dependence, greatest number of problems related to misuse and the greatest mental health problems. The dabblers report the fewest problems and symptoms, while the other two classes experiences problems and symptoms in between the classes on the extremes.

DISCUSSION AND CONCLUSIONS

Prevention efforts should take into account that young adults who misuse prescription drug have different profiles of misuse, and there may be a need for varied interventions to target these different types of misuse.

Use of synthetic cathinones and cannabimimetics among injection drug users in San Diego, California

BACKGROUND

Use of synthetic cathinones (SC) and cannabimimetics (i.e., "THC homologues" [TH]) is associated with adverse health effects. We investigated the epidemiology of synthetic drug use among a cohort of injection drug users (IDUs) in San Diego, California.

METHODS

We used logistic regression analysis to identify correlates of SC and TH use among 485 IDUs enrolled from June 2012 to September 2013.

RESULTS

Seven percent of participants reported ever using SC and 30% reported ever using TH. In multivariate logistic regression, age and recent hospitalization were significantly associated with odds of SC use (Adjusted Odds Ratio [AOR] 0.93, 95% Confidence Interval [C.I.] 0.90, 0.97; and AOR 2.34 95% C.I. 1.00, 5.49, respectively) and TH use (AOR 0.96, 95% C.I. 0.94, 0.98; and AOR 2.62, 95% C.I. 1.47, 4.68, respectively). Use of methamphetamine (AOR 9.35, 95% C.I. 1.20, 72.79) and club drugs in the past six months (AOR 3.38, 95% C.I. 1.17, 9.76) were significantly associated with SC use. Being on probation/parole (AOR 2.42, 95% C.I. 1.44, 4.07), initiating injection drug use with stimulants (AOR 1.89 95% C.I. 1.13, 3.16), and past six-month marijuana (AOR 9.22, 95% C.I. 4.49, 18.96) and prescription drug use (AOR 1.98, 95% C.I. 1.20, 3.27) were significantly associated with TH use.

CONCLUSIONS

A considerable proportion of IDU use synthetic drugs and may experience harms associated with their use. Findings have implications for criminal justice system management. Prevention efforts should emphasize the risks associated with rapidly changing synthetic formulations, and the potential harms associated with polydrug use.

Self-reported prevalence of dependence of MDMA compared to cocaine, mephedrone and ketamine among a sample of recreational poly-drug users

BACKGROUND

Evidence regarding MDMA (ecstasy) dependence and the most suitable criteria for its assessment are controversial. This study aimed to assess the prevalence of last year symptoms of dependence upon MDMA compared to cocaine, mephedrone and ketamine among a large global non-treatment seeking sample.

METHODS

A cross-sectional anonymous online survey was promoted by a UK-based dance music website between 15 November 2010 and 1 January 2011. Endorsement of DSM-IV (Diagnostic and Statistical Manual of Mental Disorders) dependence criteria was sought from all last year users of MDMA, cocaine, mephedrone and ketamine. Reporting ≥3 dependence symptoms was indicative of dependence. Logistic regression models with Generalized Estimating Equations were used to compare dependence symptoms between groups.

RESULTS

MDMA users were more likely to report ≥3 DSM-IV dependence symptoms compared to users of cocaine (odds ratio OR 0.81, 95% confidence interval CI 0.71-0.93), mephedrone (OR 0.91, 95%CI 0.78-1.06) and ketamine (OR 0.52, 95%CI 0.44-0.62) (p<0.001). MDMA users were less likely to report desire to use less or get help compared to users of other substances (p<0.001). MDMA got the highest rating of pleasurable high (mean 8.2±1.7) and lowest rating for risk of harm (mean 2.7±2.4).

CONCLUSIONS

Our results highlight the self-reported dependence potential of MDMA but low desire to use less or get help. MDMA's pleasurable effects may compensate for drug-related problems and, therefore, DSM-IV criteria may not be suitable for assessing MDMA dependence. Further research is needed on the ability of DSM-V to assess MDMA dependence.

Patients on Opioid Substitution Treatment in the Republic of Macedonia: What Do Treatment Demand Data Tell Us?

AIM: The aim of the survey is to analyze national data from opioid substitution treatment (OST) medical records and to compare it with the data from EU countries.MATERIAL AND METHODS: The survey is quantitative analytical cross-sectional study conducted in the period September - December 2013. Medical records from all patients on OST at national level during the year 2012 were analyzed. EMCDDA questionnaire from treatment protocol 3.0 was used. Data for OST patients on MMT was take from all 12 public treatment facilities, three private centers and 3 prisons. Data for OST patients on buprenorphine was taken from public clinic as the only one responsible for this type of treatment.RESULTS: A comprehensive network, diverse models of treatment intervention exists in the MKD. Total number of OST patients in 2012 in all treatment facilities was 1857 (1356 are in public, 141 in private, 360 in prison settings) 10% are on Buprenorphine and 90% are on Methadone, 52% in age group 20-34. Ratio of male to female heroin clients is 9:1; 162 are female (9 %); 107(66%) are in treatment in the age group 20-34. Average number of OST patients is 0.1% of the total population in each of the 10 cities analyzed. The mean age at first heroin use is 18 years. 40% of patients haven’t high school. With their family lives 65% of OST patients; 487 patients (36%) have children; 80% of patients use of benzodiazepines.CONCLUSION: Although treatment network of drug addiction is quite developed, perceived need for further capacity building and increase the quality of medical care implies increasing the availability, diversification in terms of sensitivity to cultural differences, gender, age, ethnicity, as well as the treatment of dependence of different types of psychoactive substances.

Ketamine use among regular tobacco and alcohol users as revealed by respondent driven sampling in Taipei: prevalence, expectancy, and users' risky decision making

The popularity of ketamine for recreational use among young people began to increase, particularly in Asia, in 2000. To gain more knowledge about the use of ketamine among high risk individuals, a respondent-driven sampling (RDS) was implemented among regular alcohol and tobacco users in the Taipei metropolitan area from 2007 to 2010. The sampling was initiated in three different settings (i.e., two in the community and one in a clinic) to recruit seed individuals. Each participant was asked to refer one to five friends known to be regular tobacco smokers and alcohol drinkers to participate in the present study. Incentives were offered differentially upon the completion of an interview and successful referral. Information pertaining to drug use experience was collected by an audio computer-assisted self-interview instrument. Software built for RDS analyses was used for data analyses. Of the 1,115 subjects recruited, about 11.7% of the RDS respondents reported ever having used ketamine. Positive expectancy of ketamine use was positively associated with ketamine use; in contrast, negative expectancy inversely associated with ketamine use. Decision-making characteristics as measured on the Iowa Gambling Task using reinforcement learning models revealed that ketamine users learned less from the most recent event than both tobacco- and drug-naïve controls and regular tobacco and alcohol users. These findings about ketamine use among young people have implications for its prevention and intervention.

Concurrent and simultaneous polydrug use: latent class analysis of an Australian nationally representative sample of young adults

BACKGROUND

Alcohol use and illicit drug use peak during young adulthood (around 18-29 years of age), but comparatively little is known about polydrug use in nationally representative samples of young adults. Drawing on a nationally representative cross-sectional survey (Australian National Drug Strategy Household Survey), this study examines polydrug use patterns and associated psychosocial risk factors among young adults (n = 3,333; age 19-29).

METHOD

The use of a broad range of licit and illicit drugs were examined, including alcohol, tobacco, cannabis, cocaine, hallucinogens, ecstasy, ketamine, GHB, inhalants, steroids, barbiturates, meth/amphetamines, heroin, methadone/buprenorphine, other opiates, painkillers, and tranquilizers/sleeping pills. Latent class analysis was employed to identify patterns of polydrug use.

RESULTS

Polydrug use in this sample was best described using a 5-class solution. The majority of young adults predominantly used alcohol only (52.3%), alcohol and tobacco (34.18%). The other classes were cannabis, ecstasy, and licit drug use (9.4%), cannabis, amphetamine derivative, and licit drug use (2.8%), and sedative and alcohol use (1.3%). Young adult males with low education and/or high income were most at risk of polydrug use.

CONCLUSION

Almost half of young adults reported polydrug use, highlighting the importance of post-high school screening for key risk factors and polydrug use profiles, and the delivery of early intervention strategies targeting illicit drugs.

Control over drug acquisition, preparation and injection: Implications for HIV and HCV risk among young female injection drug users

Young female injection drug users (IDUs) are at risk for HIV/HCV, and initiating the use of a new drug may confer additional and unexpected risks. While gender differences in the social context of injection drug use have been identified, it is unknown whether those differences persist during the initiation of a new drug. This mixed-methods study examined the accounts of 30 young female IDUs in Los Angeles, CA, USA from 2004 to 2006, who described the social context of initiating injection drug use and initiating ketamine injection. The analysis aimed to understand how the social context of young women's injection events contributes to HIV/HCV risk. Women's initiation into ketamine injection occurred approximately 2 years after their first injection of any drug. Over that time, women experienced changes in some aspects of the social context of drug injection, including the size and composition of the using group. A significant proportion of women described injection events characterized by a lack of control over the acquisition, preparation, and injection of drugs, as well as reliance on friends and sexual partners. Findings suggest that lack of control over drug acquisition, preparation, and injection may elevate women's risk; these phenomena should be considered as a behavioral risk factor when designing interventions.

Gender differences in abusers of amphetamine-type stimulants and ketamine in southwestern China

The objective of this study was to investigate abuse conditions of new-type drugs for users who are seeking treatment, gender differences, and differences between the amphetamine-type stimulants (ATS) users and mixed amphetamine-type stimulants and ketamine (ATS+K) poly-drug users. A retrospective analysis was conducted of patients with a final diagnosis of the substance use disorder according to the Diagnoses and Statistical Manual of Mental Disorders Fourth Edition (DSM-IV) who underwent treatment for exposure to new-type drugs at the mental health center of the West China Hospital from March 2009 to May 2011. A questionnaire was used to collect information about socio-demographics, drug abuse conditions and psychiatric co-morbidities. Male subjects were older (p=0.026), had low level education (p=0.003), were less previously married (p<0.001), were more likely to be employed and to hold higher status jobs (p=0.007); 77.1% of subjects had a psychotic disorder, 28.0% of subjects had a mood disorder, 39.7% had an anxiety disorder, and 45.0% had a cognitive impairment disorder. More men used methamphetamine MA (p<0.001), tobacco (p=0.014) and more than one drug substance (p=0.004) compared to women; women were more vulnerable to mood disorders (p=0.034) than men. For the males, the ATS+K patients were more likely to use 3, 4-methylenedioxymethamphetamine MDMA (p<0.001) and develop more psychotic disorders (p=0.04) than the ATS patients; for females, the ATS+K patients were more likely to use MDMA (p=0.002), alcohol (p=0.014) and develop more cognitive impairment disorder (p=0.034). The present study found that the new-type drug patients have a high degree of psychiatric morbidities; more men were using MA, tobacco and multi-substance and more women patients experience mood disorder in the gender differences. For the males, the ATS+K patients were more likely to use MDMA (3, 4-methylenedioxymethamphetamine) and develop more psychotic disorders than the ATS patients; for females, the ATS+K patients were more likely to use MDMA, alcohol and develop more cognitive impairment disorder. These results suggested that the psychiatrists should focus on the mood disorder among females, psychotic disorders among males who abuse ATS and ketamine, and cognitive impairment disorder for the females who abuse ATS and ketamine.

Cocaine use trajectories of club drug-using young adults recruited using time-space sampling

Cocaine is the most widely used club drug. Yet, little is known about how patterns of cocaine use vary over time among young adults of diverse gender and sexual identities. This study used latent class growth analysis to identify trajectories of cocaine use over a year and explored individual and substance use factors associated with these trajectories. A sample of 400 young adults (mean age=23.9 years) with recent club drug use were recruited from New York City bars and nightclubs using time-space sampling. Participants completed quantitative measures at baseline, 4-, 8- and 12-months follow-up. A 4-class model fit the data best. Patterns were: Consistent use (48%), Inconsistent use (14%), Decreasing Likelihood of use (28%), and Consistent non-use (11%). Those most likely to be in the Consistent use class had the highest frequency of baseline club drug dependence (χ2 (3, 397)=15.1, p<.01), cocaine dependence (χ2 (3, 397) = 18.9, p<.01), recent alcohol use (χ2 (3, 397)=12.48, p<.01), and drug sensation-seeking (χ2 (3, 397)=9.03, p<.01). Those most likely to be in the Consistent Non-use class had the highest frequency of baseline marijuana use (χ2 (3, 397)=2.71, p<.05). Contrary to hypotheses, there were no differences in most-likely trajectory class by gender/sexual-orientation, age, ethnicity, education, employment status, or income. Findings highlight the diversity of cocaine use patterns over time among young adults, and the personal and substance use characteristics that are associated with each.

Longitudinal trajectories of ketamine use among young injection drug users

BACKGROUND

Ketamine is a dissociative anaesthetic that became increasingly popular in the club and rave scene in the 1980s and 1990s. Reports surfaced in the late 1990s indicating that ketamine was being injected in several U.S. cities by young injection drug users (IDUs). Since all studies on ketamine injection were cross-sectional, a longitudinal study was undertaken in 2005 to determine: characteristics of young IDUs who continue to inject ketamine; frequency of ketamine injection over an extended time period; risks associated with ongoing ketamine injection; and environmental factors that impact patterns of ketamine use.

METHODS

Young IDUs aged 16-29 with a history of injecting ketamine (n=101) were recruited from public locations in Los Angeles and followed during a 2-year longitudinal study. A semi-structured instrument captured quantitative and qualitative data on patterns of ketamine injection and other drug use. A statistical model sorted IDUs who completed three or more interviews (n=66) into three groups based upon patterns of ketamine injection at baseline and follow-up. Qualitative analysis focused on detailed case studies within each group.

RESULTS

IDUs recruited at baseline were typically in their early 20s, male, heterosexual, white, and homeless. Longitudinal injection trajectories included: "Moderates," who injected ketamine several times per year (n=5); "Occasionals," who injected ketamine approximately once per year (n=21); and "Abstainers," who did not inject any ketamine during follow-up (n=40). Findings suggest that ketamine is infrequently injected compared to other drugs such as heroin, cocaine, and methamphetamine. Most IDUs who begin injecting ketamine will stop or curb use due to: negative or ambivalent experiences associated with ketamine; an inability to find the drug due to declining supply; or maturing out of injecting drugs more generally.

CONCLUSION

Reducing ketamine injection among young IDUs may best be accomplished by targeting particular groups of IDUs identified in this study, such as homeless youth and homeless travellers.

Gender and sexuality in the field: a female ethnographer's experience researching drug use in dance clubs

This article provides an account of a female ethnographer's experience accessing participants and observing drug-using behaviors in highly sexualized dance clubs. Specifically, it describes how the researcher as a gendered and sexualized self can compromise safety and inhibit access while also serving as an advantage to establishing rapport. The author describes how various methods were employed to appear as part of the cultural scene and access participants, while avoiding, and responding to, unwanted sexual advances. To address such challenges, the author provides both practical and procedural suggestions for researchers and research institutions.

Typology of club drug use among young adults recruited using time-space sampling

The present study examined patterns of recent club drug use among 400 young adults (18-29) recruited using time-space sampling in NYC. Subjects had used at least one of six club drugs (methylenedioxymethamphetamine (MDMA), ketamine, gamma-hydroxybutyrate (GHB), cocaine, methamphetamine, and D-lysergic acid diethylamide (LSD)) within the prior 3 months. We used latent class analysis (LCA) to estimate latent groups based on patterns of recent club drug use and examined differences in demographic and psychological variables by class. A 3-class model fit the data best. Patterns were: Primary cocaine users (42% of sample), Mainstream users (44% of sample), and Wide-range users (14% of sample). Those most likely to be Primary cocaine users were significantly less likely to be heterosexual males and had higher educational attainment than the other two classes. Those most likely to be Wide-range users were less likely to be heterosexual females, more likely to be gay/bisexual males, dependent on club drugs, had significantly greater drug and sexual sensation seeking, and were more likely to use when experiencing physical discomfort or pleasant times with others compared to the other two groups. Findings highlight the utility of using person-centered approaches to understand patterns of substance use, as well as highlight several patterns of club drug use among young adults.

THE FIRST INJECTION EVENT: DIFFERENCES AMONG HEROIN, METHAMPHETAMINE, COCAINE, AND KETAMINE INITIATES

This article describes how the drug type injected at the first injection event is related to characteristics of the initiate, risk behaviors at initiation, and future drug-using trajectories. A diverse sample (n=222) of young injection drug users (IDUs) were recruited from public settings in New York, New Orleans, and Los Angeles during 2004 and 2005. The sample was between 16 and 29 years old, and had injected ketamine at least once in the preceding two years. Interview data was analyzed both quantitatively and qualitatively. Young IDUs initiated with four primary drug types: heroin (48.6%), methamphetamine (20.3%), ketamine (17.1%), and cocaine (14%). Several variables evidenced statistically significant relationships with drug type: age at injection initiation, level of education, region of initiation, setting, mode of administration, patterns of self-injection, number of drugs ever injected, current housing status, and their hepatitis C virus (HCV) status. Qualitative analyses revealed that rationale for injection initiation and subjective experiences at first injection differed by drug type.

Causes and consequences of increasing club drug use in China: a descriptive assessment

Club drugs have quickly become the most widespread "drugs of abuse" in China. Using data from a convenience sample of 730 club drug users in Shanghai in 2006 , we explored the causes and consequences of club drug use. Descriptive analyses suggest that club drug use is typically polydrug use. Polydrug use is strongly associated with weakened social control, drug use social influences, and a sensation-seeking personality; in addition, it is associated with more negative health and social consequences. Both polydrug and single-club-drug users are at high risk of sexually acquiring and/or transmitting HIV. The study's limitations are noted, and future research is suggested.

Multiple drug use and polydrug use amongst homeless traveling youth

Diverse forms of drug use are an emerging theme within research on young people and substance use. This manuscript, based on a three city study of health risks amongst young injection drug users, explores multiple drug use and polydrug use amongst a subset of homeless youth referred to as "travelers." In particular, we outline characteristics of homeless traveler youths and the various ways in which they practiced multiple drug use and polydrug use. From here, we discuss some theoretical and public health implications of multiple drug use and polydrug use amongst this particular population.

A TYPOLOGY OF DRUG-RELATED OFFENDING AMONG YOUNG HOMELESS INJECTION DRUG USERS

Research indicates a link between drug use and offending, particularly amongst high-risk individuals, such as homeless youth. The extent to which such youth interpret their offending as being related to their drug use, though, is understudied. This manuscript investigates the interpretations of drug-related offenses offered by 151 primarily white, male, homeless IDUs aged 16-29 years. Youth were asked specific questions about their drug-related offenses during in-depth interviews as part of a larger study investigating health risks surrounding drug injection between 2004 and 2006. The first section of the manuscript outlines offenses youth revealed committing either in pursuit of or after using a variety of substances. The second part of the manuscript examines the overall context (motivation, environment), and provides a seven-tiered typology of drug-related offending based on youth's interpretations, linking certain drugs to specific offenses within particular contexts. From here, some theoretical and practical implications of the findings are discussed.

Polydrug use among club-going young adults recruited through time-space sampling

The Club Drugs and Health Project was supported by a grant from the National Institute on Drug Abuse (R01-DA014925-02, Jeffrey T. Parsons, Principal Investigator). Christian Grov was supported as a postdoctoral fellow in the Behavioral Sciences training in drug abuse research program sponsored by Public Health Solutions and the National Development and Research Institutes, Inc. (NDRI) with funding from the National Institute on Drug Abuse (T32 DA07233). The authors recognize the contributions of the Club Drug and Health Project team-Michael Adams, Virginia Andersen, Anthony Bamonte, Jessica Colon, Armando Fuentes, Sarit A. Golub, Chris Hietikko, Eda Inan, Juline Koken, Jose E. Nanin, Anthony Surace, Julia Tomassilli, Jon Weiser, Brooke E. Wells, and the recruitment team. An earlier version of this paper was presented at the 2008 meeting of the College on Problems of Drug Dependence (CPDD). Though some researchers have indicated club drug users are more likely to be polydrug users, there remains little known about the prevalence and specific combinations of the substances they use. Between 2004 and 2006, and using time-space sampling, a stratified sample of 400, 18-29-year-old New York City club-going, drug-using young adults were recruited into the Club Drugs and Health Project. Most participants (91.7%) had engaged in polydrug usage and 1,670 combinations of drugs were reported. Ecstasy (86.6% of users) and cocaine (85.7% of users) were the two most-frequently reported club drugs used in combination with other substances. In terms of poly-club drug combinations, ecstasy appeared to be the "universal compliment" as this drug was most often cited in combinations with other club drugs (specifically ecstasy + ketamine, ecstasy + cocaine, ecstasy + gamma hydroxybutyrate or GHB). Other frequently cited drug combinations included cocaine and marijuana, ecstasy and marijuana, LSD and marijuana, and cocaine and alcohol. These data highlight the need to develop drug health-education and prevention messages targeted at polydrug usage.

Molecular and contextual markers of hepatitis C virus and drug abuse

The spread of hepatitis C virus (HCV) infection involves a complex interplay of social risks, and molecular factors of both virus and host. Injection drug abuse is the most powerful risk factor for HCV infection, followed by sexual transmission and additional non-injection drug abuse factors such as co-infection with other viruses and barriers to treatment. It is clearly important to understand the wider context in which the factors related to HCV infection occur. This understanding is required for a comprehensive approach leading to the successful prevention, diagnosis, and treatment of HCV. An additional consideration is that current treatments and advanced molecular methods are generally unavailable to socially disadvantaged patients. Thus, the recognition of behavioral/social, viral, and host factors as components of an integrated approach to HCV is important to help this vulnerable group. Equally important, this approach is key to the development of personalized patient treatment - a significant goal in global healthcare. In this review, we discuss recent findings concerning the impact of drug abuse, epidemiology, social behavior, virology, immunopathology, and genetics on HCV infection and the course of disease.

Settings and functions related to simultaneous use of alcohol with marijuana or cocaine among clients in treatment for substance abuse

OBJECTIVES

The paper identifies the central theoretical components for developing a typology of alcohol use with other substances. The settings and functions related to the simultaneous use of alcohol with marijuana or cocaine are examined using a dataset from a study of treatment clients in Ontario, Canada (data collected between the years 2003 and 2005).

METHODS

A cross-sectional design was used where patients 18 years or older completed a self-administered questionnaire upon admission to various treatment programs. Clients who reported using marijuana (n = 499) or cocaine (n = 375) in the past year were asked how often they use these substances in combination with alcohol.

FINDINGS

Simultaneous use is very common among treatment clients, with differences in the settings and functions associated with alcohol used in combination with cocaine or marijuana, and by various sociodemographic characteristics. The study's limitations are noted.

Predictors and comparisons of polydrug and non-polydrug cocaine use in club subcultures

BACKGROUND/OBJECTIVES

Club drug users have been shown to tend towards patterns of polydrug use, which has been linked to adverse health outcomes, such as impaired mental health, overdose, dependence, infectious disease exposure, and decreased cognitive functioning.

METHODS

We analyzed data from the Club Drugs and Health Project, a study designed to examine the patterns and contexts of club drug use among young adults. Four-hundred recent club drug users were recruited through time-space sampling.

RESULTS

Among recent cocaine users (n = 361), 61.2% were polydrug users. Male gender was predictive of polydrug cocaine use (OR = 1.66). Gay, lesbian, and bisexual (GLB) sexual orientation, White race, and Non-Latino ethnicity were not. No differences in mental health factors were found between cocaine polydrug users and users of only cocaine. However, polydrug users were significantly more likely to score high on drug-related sensation seeking as well as to use drugs to deal with unpleasant emotions and to have pleasant times with others.

CONCLUSIONS

Prevention and intervention efforts should account for contextual and motivational factors in attempting to reduce polydrug use and its negative effects.

"Research chemicals": tryptamine and phenethylamine use among high-risk youth

Tryptamines and phenethylamines are two broad categories of psychoactive substances with a long history of licit and illicit use. Profiles of users of recently emerging tryptamines and phenethylamines are nonexistent, however, since surveillance studies do not query the use of these substances. This manuscript describes the types, modes of administration, onset of use, and context of use of a variety of lesser known tryptamines and phenethylamines among a sample of high-risk youth. Findings are based upon in-depth interviews with 42 youth recruited in public settings in Los Angles during 2005 and 2006 as part of larger study examining health risks associated with injecting ketamine. Youth reported that their use of tryptamines and phenethylamines was infrequent, spontaneous, and predominately occurred at music venues, such as festivals, concerts, or raves. Several purchased a variety of these "research chemicals" from the Internet and used them in private locations. While many described positive experiences, reports of short-term negative health outcomes included nausea, vomiting, diarrhea, disorientations, and frightening hallucinations. These findings, based upon pilot study data, move toward an epidemiology of tryptamine and phenethylamine use among high-risk youth.

Towards an Explanation of Subjective Ketamine Experiences among Young Injection Drug Users

Ketamine is a dissociative anesthetic with powerful sedative and hallucinogenic properties. Despite the wide variability in reported subjective experiences, no study has attempted to describe the particular factors that shape these experiences. This manuscript is based upon a sample of 213 young injection drug users recruited in New York, New Orleans, and Los Angeles with histories of ketamine use. Qualitative interviews focused on specific ketamine events, such as first injection of ketamine, most recent injection of ketamine, and most recent experience sniffing ketamine. Findings indicate that six factors impacted both positive and negative ketamine experiences: polydrug use, drug using history, mode of administration, quantity and quality of ketamine, user group, and setting. Most subjective experiences during any given ketamine event were shaped by a combination of these factors. Additionally, subjective ketamine experiences were particularly influenced by a lifestyle characterized by homelessness and traveling.

HIV Sexual Risk Behaviors among Ketamine and Non-Ketamine Using Criminal Offenders Prior to Prison Entry

This study is the first to examine ketamine use and its association with HIV sexual risk behaviors among a criminal offending population in the United States. Data were collected from 716 inmates as part of the Transitional Case Management (TCM) protocol within the Criminal Justice Drug Abuse Treatment Studies (CJ-DATS) cooperative agreement. Bivariate analyses were used to identify differences between ketamine users (n=44) and non-ketamine users (n=672). Three Poisson regression models were used to identify the significant correlates of high risk sexual behaviors in the 30 days prior to incarceration-- (1) number of times had unprotected sex while high, (2) number of times had unprotected vaginal sex, and (3) number of times had unprotected anal sex. Results indicate that ketamine was a significant correlate in all of the Poisson regression models. Findings add to the literature and indicate that ketamine use may be a marker for engaging in HIV risk behaviors among criminal offenders.

Timing of alcohol and other drug use

Many Americans who drink alcohol are polydrug users--that is, they also use other psychoactive drugs, such as nicotine, pharmaceuticals, cannabis, and other illicit substances. Polydrug use is a general term that describes a wide variety of substance use behaviors. Different types of polydrug use can be described with regard to the timing of the ingestion of multiple substances. Concurrent polydrug use (CPU) is the use of two or more substances within a given time period, such as a month or a year. Simultaneous polydrug use (SPU) is the use of two or more substances in combination (i.e., at the same time or in temporal proximity) (Grant and Harford 1990a). Thus, although all simultaneous polydrug users are, by definition, concurrent users, concurrent users may or may not be simultaneous users. This article describes the functions of SPU for substance users, as well as the measurement, prevalence, patterns, and consequences of SPU.

First injection of ketamine among young injection drug users (IDUs) in three U.S. cities

Ketamine, a dissociative anesthetic, has emerged as an increasingly common drug among subgroups of young injection drug users (IDUs) in cities across the United States. In-depth qualitative interviews were conducted with 213 young IDUs aged 16-28 years recruited in New York, New Orleans, and Los Angeles between 2004 and 2006. While some initiated injection drug use with ketamine, the drug was more frequently injected by IDUs with extensive polydrug using histories. IDUs initiating with ketamine commonly self-injected via an intramuscular mode of administration. The injection group provided crucial knowledge and material resources that enabled the injection event to occur, including ketamine, syringes, and injection skills. Injection paraphernalia was commonly shared during the first injection of ketamine, particularly vials of pharmaceutically-packaged liquid ketamine. Injection events infrequently occurred in a rave or club and more typically in a private home, which challenges ketamine's designation as a 'club' drug. The first injection of ketamine was a noteworthy event since it introduced a novel drug or new mode of administration to be further explored by some, or exposed others to a drug to be avoided in the future. Risk reduction messages directed towards young IDUs should be expanded to include ketamine.

Patterns of ketamine use among young injection drug users

Ketamine is a dissociative anesthetic that has emerged as an increasingly popular choice among young drug users. Recent research indicates the presence of hidden populations of young people who inject ketamine in New York and other U.S. cities. Applying an ethno-epidemiological approach, the authors recruited 40 young injection drug users (IDUs) (< 25 years old) in New York City to explore health risks associated with ketamine use. This analysis looks at the varying patterns and frequencies of ketamine injection by examining personal, social, and cultural aspects of these young people's lives. We learned that drug-using histories, experiential dimensions, sociocultural characteristics, and associations with other young people help account for the different patterns of injecting ketamine within the sample. In particular, these findings indicate that young people who were more frequent ketamine injectors had the following characteristics: initiated injection drug use with ketamine; enjoyed the effects of ketamine, were stably housed; lived in the vicinity of New York City; and associated with others who also injected ketamine.

Ketamine : from medicine to misuse

This review describes the medical, research and recreational uses of ketamine, an anaesthetic derivative of phencyclidine that has dissociative, analgesic and psychedelic properties. Ketamine has a complex mechanism of action that is further complicated by stereoselectivity; however, antagonism of glutamate NDMA receptors is thought to underlie its analgesic, dissociative and neuroprotective effects. While ketamine use in medical and veterinary settings is well documented and has a good safety record, the increase in its unregulated use outside of such controlled environments is a cause for concern. The impact on higher centres in the brain, particularly altered perception of auditory, visual and painful stimuli, results in a general lack of responsive awareness that puts the recreational user at (often unrecognised) risk of personal harm. The perceptual and mood changes observed in those who have consumed ketamine are highly sensitive to age, dose, route of administration, previous experience and setting. At low doses, stimulant effects predominate and the effect of environmental conditions are significant; with higher doses, psychedelic effects predominate and the effect of the environment diminishes. The potential of ketamine as a novel clinical and research tool is matched by its abuse potential outside medical settings.

Adolescent drug & alcohol use in the 21st century

Screening for drug abuse should be a part of adolescent health maintenance visits. Good interviewing skills using open-ended, nonjudgmental questions in a private setting may elicit a history of drug abuse. A detailed and comprehensive history is important to recognize family dynamics, early behavioral changes (Table 5, see page 198), comorbid psychiatric conditions, and the adolescent's attitude toward substances of abuse. A good physical exam may reveal clinical sequelae of drug abuse. Testing for drug abuse should be done with the patient's consent except in cases where judgment is impaired. Periodic screening for drugs is a part of drug treatment and rehabilitation. The typical pediatrician is not equipped to provide drug counseling and treatment to the abusing adolescent. Specialized referral centers would be ideal, and clinicians need to be aware of local resources in their communities. Anticipatory guidance explaining the ill effects of drugs is mandatory. Prevention should be aimed at increasing public awareness of the consequences of drug abuse, improving parenting techniques, and introducing school-based drug prevention programs. The fight against substance abuse needs to be a community effort in which the individual, the family and the primary care physician play important roles.

Club drugs as causal risk factors for HIV acquisition among men who have sex with men: a review

We reviewed medical and psychology databases for articles published between January 1980 and August 2005 demonstrating associations between HIV/Sexually Transmitted Infection risk and club drug use. Seventy-four articles were reviewed, of which 30 provided adjusted risk ratios for associations between HIV/sexually transmitted infection risk and club drug use among men who have sex with men. Definitions and lists of club drugs were broad and inconsistent. We constructed a conceptual framework of biologically plausible pathways for causation. Using Hill's criteria to examine club drugs as causal risk factors for HIV, we found the most evidence for methamphetamine and volatile nitrites; however, more studies are needed.