Enzymatic assay for urine lactose in the assessment of recent intravenous abuse of buprenorphine.

Urine samples were analyzed for lactose to investigate if elevated lactose concentrations indicate recent (< 48 hours) intravenous abuse of substances containing lactose as an excipient. Elevated lactose levels were found in samples given by patients who had recently injected substances intravenously, verified by fresh injection marks. Urine lactose assay can support clinical and toxicological findings when assessing substance abuse.

Use of rapid fentanyl test strips among young adults who use drugs.

BACKGROUND: The overdose epidemic has been exacerbated by a dramatic increase in deaths involving illicitly manufactured fentanyl (IMF). Drug checking is a novel strategy to identify IMF in illicit drugs. We examined the uptake and acceptability of rapid fentanyl test strips among young adults. METHODS: From May to September 2017, we recruited 93 young adults in Rhode Island who reported injecting drugs or using heroin, cocaine, or illicitly obtained prescription pills in the past 30 days. Participants were asked to test either their urine after drug use (post-consumption) or a drug sample prior to use (pre-consumption) using rapid fentanyl test strips. After a questionnaire and a brief training, participants received ten strips for their personal use and were asked to return for a one-month follow-up visit, which assessed the uptake and acceptability of the rapid strips tests and the behavioral outcomes associated with receipt of a positive test. RESULTS: Of the 81 (87%) participants who returned for follow-up and who had complete data, the mean age was 27, 45 (56%) were male, and 37 (46%) were non-white. A total of 62 participants (77%) reported using at least one test strip. Of these, 31 (50%) received at least one positive result. A positive result was associated with older age, homelessness, heroin use, injection drug use, ever witnessing an overdose, and concern about overdose or drugs being laced with fentanyl (all p < 0.05). Receiving a positive result was significantly associated with reporting a positive change in overdose risk behavior between baseline and follow-up (p ≤ 0.01). Among all participants, 79 (98%) reported confidence in their ability to use the test strips and 77 (95%) wanted to use them in the future. CONCLUSIONS: Young adults reported high uptake and acceptability of fentanyl test strips to detect IMF in illicit drugs.

Urine drug screening for early detection of unwitting use of fentanyl and its analogues among people who inject heroin in Sydney, Australia.

INTRODUCTION AND AIMS: North America has witnessed a dramatic rise in fatal opioid overdoses due to the unwitting consumption of non-pharmaceutical fentanyl and its analogues. While some of the drivers of this crisis-including profitability and access to high-potency opioids through internet sources-also apply in Australia, to our knowledge, there have been no ongoing surveillance studies of local populations. Therefore, this pilot study aimed to detect unintentional fentanyl consumption among people who inject heroin through instant urine screening, and determine the feasibility and acceptability of voluntary urinalysis of clients at the Medically Supervised Injecting Centre, Kings Cross, Sydney. DESIGN AND METHODS: Brief surveys and urine drug screens were conducted with 67 participants in Wave 1 (October 2017) and 51 participants in Wave 2 (March 2018). Urine samples were tested with BTNX Rapid Response™ fentanyl urine strip test at a detection level of 20 ng/mL norfentanyl. These strips also cross-react to numerous fentanyl analogues. RESULTS: There were no cases where positive urine tests suggested unwitting fentanyl use detected in this study. DISCUSSION AND CONCLUSIONS: These negative findings contrast sharply with similar Canadian studies. While no cases of fentanyl-laced heroin use have been detected so far, we have demonstrated that this surveillance design is low-cost, feasible and scalable approach to monitoring the considerable public-health threat of undetected fentanyl and its analogues in Australia. Further validation of cross-reactivity of test strips would strengthen this method.

Evaluation of a fentanyl drug checking service for clients of a supervised injection facility, Vancouver, Canada.

BACKGROUND: British Columbia, Canada, is experiencing a public health emergency related to opioid overdoses driven by consumption of street drugs contaminated with illicitly manufactured fentanyl. This cross-sectional study evaluates a drug checking intervention for the clients of a supervised injection facility (SIF) in Vancouver. METHODS: Insite is a facility offering supervised injection services in Vancouver's Downtown East Side, a community with high levels of injection drug use and associated harms, including overdose deaths. During July 7, 2016, to June 21, 2017, Insite clients were offered an opportunity to check their drugs for fentanyl using a test strip designed to test urine for fentanyl. Results of the drug check were recorded along with information including the substance checked, whether the client intended to dispose of the drug or reduce the dose and whether they experienced an overdose. Logistic regression models were constructed to assess the associations between drug checking results and dose reduction or drug disposal. Crude odds ratios (OR) and 95% confidence intervals (CI) were reported. RESULTS: About 1% of the visits to Insite during the study resulted in a drug check. Out of 1411 drug checks conducted by clients, 1121 (79.8%) were positive for fentanyl. Although most tests were conducted post-consumption, following a positive pre-consumption drug check, 36.3% (n = 142) of participants reported planning to reduce their drug dose while only 11.4% (n = 50) planned to dispose of their drug. While the odds of intended dose reduction among those with a positive drug check was significantly higher than those with a negative result (OR = 9.36; 95% CI 4.25-20.65), no association was observed between drug check results and intended drug disposal (OR = 1.60; 95% CI 0.79-3.26). Among all participants, intended dose reduction was associated with significantly lower odds of overdose (OR = 0.41; 95% CI 0.18-0.89). CONCLUSIONS: Although only a small proportion of visits resulted in a drug check, a high proportion (~ 80%) of the drugs checked were contaminated with fentanyl. Drug checking at harm reduction facilities such as SIFs might be a feasible intervention that could contribute to preventing overdoses in the context of the current overdose emergency.

Substance use patterns associated with recent exposure to fentanyl among people who inject drugs in Vancouver, Canada: A cross-sectional urine toxicology screening study.

INTRODUCTION: Vancouver, Canada is experiencing an opioid overdose crisis where fentanyl, a potent, synthetic opioid contaminating the illicit drug supply, has been detected in the majority of fatal overdose cases. Despite its growing presence throughout North America, few studies have characterized exposure to fentanyl among people who use illicit drugs (PWUD). We sought to identify the prevalence and correlates of fentanyl exposure among PWUD in Vancouver. METHODS: Data were derived from cohort studies of PWUD in Vancouver. In June-October 2016, we administered multi-panel urine drug screens (UDS) to detect recent exposure to fentanyl and eight other substances. Multivariable logistic regression was used to identify substance use patterns associated with recent fentanyl exposure among participants who injected drugs in the past six months (PWID). RESULTS: Among 669 PWUD including 250 (37.4%) females and 452 (67.6%) PWID, 97 (14.5%) tested positive for fentanyl. All these individuals also tested positive for other substances, most commonly for morphine/heroin (89.9%), amphetamine/methamphetamine (75.3%) and cocaine (74.2%). A fentanyl detection rate was significantly higher among PWID (19.7%) compared to non-injection drug users (3.9%) (p<0.001). In multivariable analyses, younger age (adjusted odds ratio [AOR]: 0.96) and testing positive for morphine/heroin (AOR: 6.73), buprenorphine (AOR: 4.25), amphetamine/methamphetamine (AOR: 3.26), cocaine (AOR: 2.92) and cannabis (AOR: 0.52) remained independently associated with fentanyl exposure (all p<0.05). CONCLUSION: With one in five PWID being exposed to fentanyl, there is an urgent need to design and scale up interventions to reduce overdose risk, including a range of opioid agonist therapies.

Monitoring Intravenous Abuse of Methadone or Buprenorphine in Opiate Maintenance Treatment (OMT): A Simple and Fast LC-MS-MS Method for the Detection of Disaccharides in Urine Samples.

The detection of disaccharides in urine is under investigation to act as a marker for intravenous abuse of disaccharide formulations, like liquid methadone with syrup (sucrose), methadone tablets (lactose and sucrose), or buprenorphine tablets (lactose). As the detection time in urine has not yet been investigated and a routine method for detecting disaccharides is still lacking, a study was performed to estimate the window of detection in urine after intravenous consumption of disaccharides. Furthermore, an analytical LC-MSMS method for the quantification of sucrose and lactose in urine was validated. The method was applied to urine samples of intravenous substitute consumers, with urine being sampled before intravenous use of substitutes and approximately 30 minutes later. Twenty users provided information regarding their most recent prior intravenous consumption. Disaccharides were detectable in all 20 urine samples about 30 minutes after consumption. A cut off for both disaccharides of 40mg/L was used. Based on these conditions 81% of the persons who consumed in a time frame of 24 hours ago showed positive results for disaccharides. The study showed that the validated LC-MSMS method with an easy and fast workup is usable for daily routine in the laboratory. It might be helpful for methadone and buprenorphine prescribing physicians to check whether the opiate maintenance treatment patient takes his or her substitution medicines orally as intended, or continues with intravenous misuse by injecting substitution medicines instead of heroin.

Enzymatic assays for detecting lactose and sucrose in urine to reveal intravenous drug abuse with emphasis on buprenorphine.

Buprenorphine and methadone are commonly used medications for opioid maintenance treatment (OMT), using sublingual and oral administration, respectively. Although beneficial for OMT, these drugs can also be abused by intravenous administration. In intravenous abuse cases, the adjuvants lactose and sucrose are excreted in urine without hydrolysis to monosaccharides, since there are no disaccharidases in the blood. We validated enzymatic methods for the analysis of lactose and sucrose in urine. The analytical performance of both assays was considered appropriate for detecting intravenous drug abuse. The principle was proven by analyzing 93 postmortem (PM) urine samples for lactose, following comprehensive toxicological drug screening. In addition, 32 clinical urine samples from potential drug abusers were analyzed to assess the effect of PM changes on the assay. The mean level of lactose was low in clinical samples and relatively low in PM samples in which no drugs were found. Markedly elevated levels were seen in many of the buprenorphine positive samples, suggesting intravenous administration. Enzymatic methods could provide a simple and cost effective way to assess the intravenous administration of OMT drugs or drugs of abuse. Very high levels of glucose in urine may interfere with the assays. Furthermore, other causes for elevated urine disaccharides, such as hypolactasia and increased intestinal permeability, need to be considered in the interpretation of the results. Copyright © 2016 John Wiley & Sons, Ltd.

Identifying cases of heroin toxicity where 6-acetylmorphine (6-AM) is not detected by toxicological analyses.

PURPOSE: Heroin has a half-life of 2-6 min and is metabolized too quickly to be detected in autopsy samples. The presence of 6-acetylmophine (6-AM) in urine, blood, or other samples is convincing evidence of heroin use by a decedent, but 6-AM itself has a half-life of 6-25 min before it is hydrolyzed to morphine, so 6-AM may not be present in sufficient concentration to detect in postmortem samples. Codeine is often present in heroin preparations as an impurity and is not a metabolite of heroin. Studies report that a ratio of morphine to codeine greater than one indicates heroin use. We hypothesize that the ratio of morphine to codeine in our decedents abusing drugs intravenously will be no different in individuals with 6-AM present than in individuals where no 6-AM is detected, and we report our study of this hypothesis. METHODS: All accidental deaths investigated by the Jefferson County Coroner/Medical Examiner Office from 2010 to 2013 with morphine detected in blood samples collected at autopsy were reviewed. Five deaths where trauma caused or contributed to death were excluded from the review. The presence or absence of 6-AM and the concentrations of morphine and codeine were recorded for each case. The ratio of morphine to codeine was calculated for all decedents. Any individual in whom no morphine or codeine was detected in a postmortem sample was excluded from further study. Absence or presence of drug paraphernalia or evidence of intravascular (IV) drug use was documented in each case to identify IV drug users. The proportion of the IV drug users with and without 6-AM present in a postmortem sample was compared to the M/C ratio for the individuals. RESULTS: Of the 230 deaths included in the analysis, 103 IV drug users with quantifiable morphine and codeine in a postmortem sample were identified allowing for calculation of an M/C ratio. In these IV drug users, the M/C ratio was greater than 1 in 98 % of decedents. When controlling for the absence or presence of 6-AM there was no statistically significant difference in the proportion of IV drug users when compared to non IV drug users with an M/C ratio of greater than 1 (p = 1.000). CONCLUSION: The M/C ratio in IV drug users, if greater than 1, is seen in deaths due to heroin toxicity where 6-AM is detected in a postmortem sample. This study provides evidence that a M/C ratio greater than one in an IV drug user is evidence of a death due to heroin toxicity even if 6-AM is not detected in the blood. Using the M/C ratio, in addition to scene and autopsy findings, provides sufficient evidence to show heroin is the source of the morphine and codeine. Listing heroin as a cause or contributing factor in deaths with evidence of IV drug abuse and where the M/C ratio exceeds 1 will improve identification of heroin fatalities, which will allow better allocation of resources for public health initiatives.

Experiences with urine drug testing by police among people who inject drugs in Bangkok, Thailand.

BACKGROUND: Thailand has relied on drug law enforcement in an effort to curb illicit drug use. While anecdotal reports suggest that Thai police frequently use urine toxicology to identify drug users, little is known about the prevalence or impacts of this practice among people who inject drugs (IDU). Therefore, we sought to examine experiences with urine drug testing by police among IDU in Bangkok. METHODS: Data were derived from a community-recruited sample of IDU in Bangkok participating in the Mitsampan Community Research Project between July and October 2011. We assessed the prevalence and correlates of being subjected to urine toxicology testing by police using multivariate Poisson regression. RESULTS: In total, 438 IDU participated in this study, with 293 (66.9%) participants reporting having been tested for illicit drugs by police. In multivariate analyses, reports of drug testing by police were independently and positively associated with younger age (adjusted prevalence ratio [APR]: 1.28), a history of methamphetamine injection (APR: 1.22), a history of incarceration (APR: 1.21), having been in compulsory drug detention (APR: 1.43), avoiding healthcare (APR: 1.15), and HIV seropositivity (APR: 1.19), and negatively associated with access to voluntary drug treatment (APR: 0.82) (all p<0.05). CONCLUSION: A high proportion of IDU in Bangkok were subjected to drug testing by police. Young people and methamphetamine injectors were more likely to have been tested. The findings indicate that drug testing by police is associated with the compulsory drug detention system and may be interfering with IDU's access to healthcare and voluntary drug treatment. These findings raise concern about the widespread practice of drug testing by police and its associated impacts.

Outcome assessment of a triangular clinic as a harm reduction intervention in Rajaee-Shahr Prison, Iran.

BACKGROUND: Transmission of the human immunodeficiency virus (HIV) among incarcerated injection drug users (IDU) is a health epidemic in the Islamic Republic of Iran. Triangular clinics (TCs) were established in prisons as a harm reduction measure to decrease the risk of HIV transmission and other blood-borne infections. The objective of this study was to assess the immediate outcomes of one TC among male IDUs in Iran's Rajaee-Shahr prison. METHODS: This study was conducted in two stages between 2003 and 2005. In the preparatory stage, focus group data was collected to update the prison's TC education and medical interventions and construct the self-report questionnaire. In stage two, 150 male IDUs were recruited in a closed cohort study design to assess the immediate outcome of the TC. Participants were measured at baseline and followed up to six months to measure their drug use, attitude toward and knowledge of high risk behaviours, serological conversion for HIV, HBV and HCV, and engagement in risky behaviors. The TC outcomes were determined through random urine analysis testing, a self-administered questionnaire and behaviour report cards, and viral infection testing. RESULTS: The findings of the urine analyses indicated a minimal yet consistent decrease in drug use over the six months. The pre and post- self-administered questionnaire data relayed a modest change in IDU risky behaviours associated with sexual practices; this was greater in comparison to the knowledge and attitude measures. It was determined that age may have a detrimental effect as may viral infections (HIV and HBV) on knowledge, attitude and behavior change. Both education and employment may have a protective effect. Data collected from the self-report behaviour cards similarly showed a modest reduction in high risk practices. At the six month follow-up, only one case became HIV positive, 9 HCV and 17 HBV. CONCLUSIONS: Considering that HIV is concentrated among Iranian prisoners who inject drugs at a high level, the results of this study indicate that TCs are a possible effective intervention. However, many prisoners continued with risky behaviors even if they were participating in harm reduction measures, such as methadone maintenance therapy.

Disaccharides in urine samples as markers of intravenous abuse of methadone and buprenorphine.

Methadone and buprenorphine are commonly used as oral substitutes in opiate maintenance programs to treat persons who are dependent on heroin. During these programs, patients are not allowed to continue using illicit drugs. Abstinence can easily be monitored by urine tests with immunochemical methods. It is well known that the intravenous abuse of heroin substitutes like methadone or buprenorphine has become common as well. The methadone-prescribing physician has no opportunity to check whether the opiate maintenance treatment patient takes his substitution medicines orally as intended or continues with his intravenous misuse now substituting the methadone instead of injecting heroin. In Germany, substitutes are available as liquids and tablets that contain carbohydrates as adjuvants. Sucrose is used to increase viscosity in liquids, while lactose is needed for pressing tablets (e.g., Methaddict® and Subutex®). In case of oral ingestion, disaccharides are broken down into monosaccharides by disaccharidases in the small intestine. These monosaccharides are absorbed into the blood stream by special monosaccharide transporters. Disaccharidases do not exist in blood, thus sucrose and lactose are not split if substitute medicines are injected intravenously. Our assumption, therefore, was that they are excreted unchanged in urine. We investigated a method for the detection of disaccharides in urine as markers of intravenous abuse of substitutes. Urine samples of 26 intravenous substitute abusers showed all positive results for lactose (76.9%) and/or sucrose (73.1%). The method is assumed to be useful to detect intravenous abuse of substitutes.

Promethazine misuse among methadone maintenance patients and community-based injection drug users.

OBJECTIVE: Promethazine has been reported to be misused in conjunction with opioids in several settings. Promethazine misuse by itself or in conjunction with opioids may have serious adverse health effects. To date, no prevalence data for the nonmedical use of promethazine have been reported. This study examines the prevalence and correlates of promethazine use in 2 different populations in San Francisco, California: methadone maintenance clinic patients and community-based injection drug users (IDUs). METHODS: We analyzed urine samples for the presence of promethazine and reviewed the clinical records for 334 methadone maintenance patients at the county methadone clinic. Separately, we used targeted sampling methods to recruit and survey 139 community-based opioid IDUs about their use of promethazine. We assessed prevalence and factors associated with promethazine use with bivariate and multivariate statistics. RESULTS: The prevalence of promethazine-positive urine samples among the methadone maintenance patients was 26%. Only 15% of promethazine-positive patients had an active prescription for promethazine. Among IDUs reporting injection of opiates in the community-based survey, 17% reported having used promethazine in the past month; 24% of the IDUs who reported being enrolled in methadone treatment reported using promethazine in the past month. CONCLUSIONS: The finding that one-quarter of methadone maintenance patients in a clinic or recruited in community settings have recently used promethazine provides compelling evidence of significant nonmedical use of promethazine in this patient population. Further research is needed to establish the extent and nature of nonmedical use of promethazine.

Effects of a randomized contingency management intervention on opiate abstinence and retention in methadone maintenance treatment in China.

AIMS: Methadone maintenance treatment has been made available in China in response to the rapid spread of human immunodeficiency virus (HIV), but high rates of dropout and relapse are problematic. The aim of this study was to apply and test if a contingency management (or motivational incentives) intervention can improve treatment retention and reduce drug use. DESIGN: Random assignment to usual care with (n = 160) or without (n = 159) incentives during a 12-week trial. Incentives participants earned draws for a chance to win prizes on two separate tracks targeting opiate-negative urine sample or consecutive attendance; the number of draws increased with continuous abstinence or attendance. SETTING: Community-based methadone maintenance clinics in Shanghai and Kunming. PARTICIPANTS: The sample was 23.8% female, mean age was 38, mean years of drug use was 9.4 and 57.8% had injected drugs in the past 30 days. MEASUREMENTS: Treatment retention and negative drug urine. FINDINGS: Relative to the treatment-as-usual (control) group, better retention was observed among the incentive group in Kunming (75% versus 44%), but no difference was found in Shanghai (90% versus 86%). Submission of negative urine samples was more common among the incentive group than the usual care (74% versus 68% in Shanghai, 27% versus 18% in Kunming), as was the longest duration of sustained abstinence (7.7 weeks versus 6.5 in Shanghai, 2.5 versus 1.6 in Kunming). The average total prize amount was 371 Yuan (or $55) per participant (527 for Shanghai versus 216 in Kunming). CONCLUSIONS: Contingency management improves treatment retention and drug abstinence in methadone maintenance treatment clinics in China, although there can be considerable site differences in magnitude of effects.

A comparison of aripiprazole, methylphenidate, and placebo for amphetamine dependence.

OBJECTIVE: Problems related to illegal amphetamine use have become a major public health issue in many developed countries. To date, evidence on the effectiveness of psychosocial treatments has remained modest, and no pharmacotherapy has proven effective for amphetamine dependence. METHOD: Individuals meeting DSM-IV criteria for intravenous amphetamine dependence (N=53) were randomly assigned to receive aripiprazole (15 mg/day), slow-release methylphenidate (54 mg/day), or placebo for 20 weeks. The study was terminated prematurely due to unexpected results of interim analysis. An intention-to-treat analysis was used. The primary outcome measure was the proportion of amphetamine-positive urine samples. RESULTS: Patients allocated to aripiprazole had significantly more amphetamine-positive urine samples than patients in the placebo group (odds ratio=3.77, 95% CI=1.55-9.18), whereas patients who received methylphenidate had significantly fewer amphetamine-positive urine samples than patients who had received placebo (odds ratio=0.46, 95% CI=0.26-0.81). CONCLUSIONS: Methylphenidate is an effective treatment for reducing intravenous drug use in patients with severe amphetamine dependence.

Needle exchange and injection drug use frequency: a randomized clinical trial.

Despite a lack of evidence that needle exchange programs (NEPs) cause an increase in injection drug use, there are still concerns over fostering increased injection behavior with NEPs. The design was a randomized controlled trial conducted from May 1997 to June 2000 comparing injection drug users (IDUs) who are randomly assigned to have access to an NEP versus training in how to purchase needles and syringes (NS) at pharmacies. Of 653 IDUs recruited into the study, 600 were randomized: 426 were followed-up at 6 months, and 369 were followed-up at 12 months. Four hundred ninety were followed up at least once. There was no difference in the number of injections over time between the NEP and the Pharmacy Sales arms of the study or in the percentage of positive urine test results over time between the NEP and the Pharmacy Sales arms of the study for morphine and amphetamine. The decrease in the presence of cocaine was marginally greater between the arms of the study. The results do not support the hypothesis of NEPs causing an increase in injection drug use. This clinical trial provides the strongest evidence to date that needle exchanges do not produce this negative effect.

The duration time of urine morphine detection in heroin addicts by radioimmunoassay.

Heroin is one of the most seriously abused drugs and its consumption is illegal. Therefore, the detection of the drug in addicts has to be highly accurate and reliable. Morphine detection in urine is the most common method to confirm consumption. Several methods of morphine detection in urine are described such as Latex Agglutination Inhibition (LAI), Thin Layer Chromatography (TLC), Radioimmunoassay (RIA), High Performance Liquid Chromatography (HPLC) and Gas Chromatography and Mass Spectrophotometry (GC/MS). In this study, we performed Radioimmunoassay (RIA) because it is rapid and cheap. Sixty-three male heroin addicts, average age 32 years, with an average time of heroin administration of about 3 years were studied. They used on average Q.635 grams of heroin per day. The time of detection in the urine after the last heroin administration to the first urine testing was about 8.5 hours, over 3-4 days. The amount of morphine in the urine was 17,897.9 ng/ml. Nevertheless, we found that morphine could be detected in the urine every day for seven days. The decreasing rate of daily morphine detection in the urine was 88.4, 74.2, 64.2, 57.1, 63.3 and 44.8 per cent. But there was no significant difference in the route of administration.

Voucher-based reinforcement of cocaine abstinence in treatment-resistant methadone patients: effects of reinforcement magnitude.

Voucher-based reinforcement of cocaine abstinence has been one of the most effective means of treating cocaine abuse in methadone patients, but it has not been effective in all patients. This study was designed to determine if we could promote cocaine abstinence in a population of treatment-resistant cocaine abusing methadone patients by increasing the magnitude of voucher-based abstinence reinforcement. Participants were 29 methadone patients who previously failed to achieve sustained cocaine abstinence when exposed to an intervention in which they could earn up to $1155 in vouchers (exchangeable for goods/services) for providing cocaine-free urines. Each patient was exposed in counterbalanced order to three 9-week voucher conditions that varied in magnitude of voucher reinforcement. Patients were exposed to a zero, low and high magnitude condition in which they could earn up to $0, $382, or $3480 in vouchers for providing cocaine-free urines. Analyses for 22 patients exposed to all three conditions showed that increasing voucher magnitude significantly increased patients' longest duration of sustained cocaine abstinence (P<0.001) and percent of cocaine-free urines (P<0.001), and significantly decreased patients' reports of cocaine injections (P=0.024). Almost half (45%) of the patients in the high magnitude condition achieved >/=4 weeks of sustained cocaine abstinence, whereas only one patient in the low and none in the zero magnitude condition achieved more than 2 weeks. Reinforcement magnitude was a critical determinant of the effectiveness of this abstinence reinforcement intervention.

Functional magnetic resonance imaging of the acute effect of intravenous heroin administration on visual activation in long-term heroin addicts: results from a feasibility study.

This preliminary report is the first demonstration of the acute effects of diacetylmorphine (heroin) administration on functional activation in the human brain using functional magnetic resonance imaging (fMRI). Four opiate addicts who received regular prescriptions for heroin, underwent fMRI using a visual activation paradigm before and after a dose of 30 mg heroin. All four showed a decrease after the heroin dose in the extent of significant activation. This method shows promise for sequential scanning to determine brain activity in response to different drugs and routes of drug administration.

Estimating the number of HIV-infected injection drug users in Bangkok: a capture--recapture method.

OBJECTIVES: The purpose of the study was to estimate the number of injection drug users infected with the human immunodeficiency virus (HIV) in Bangkok to allow planning for health services for this population. METHODS: A two-sample capture-recapture method was used. The first capture listed all persons on methadone treatment for opiate addiction from April 17 through May 17, 1991, at 18 facilities in Bangkok. The second capture involved urine testing of persons held at 72 Bangkok police stations from June 3 through September 30, 1991. Persons whose urine tests were positive for opiate metabolites or methadone were included on the second list. RESULTS: The first capture comprised 4064 persons and the recapture 1540 persons. There were 171 persons included on both lists, yielding an estimate of 36,600 opiate users in Bangkok. Existing data indicate that 89% of opiate users in Bangkok inject drugs and that about one third are infected with HIV, yielding an estimate of approximately 12,000 HIV-infected injection drug users in Bangkok in 1991. CONCLUSIONS: During the 1990s the number of cases of acquired immunodeficiency syndrome (AIDS) and other HIV-related diseases, including tuberculosis, in the population of HIV-infected injection drug users in Bangkok will increase dramatically, placing new demands on existing health care facilities. The capture-recapture method may be useful in estimating difficult-to-count populations, including injection drug users.