Assessing market competition and vendors’ size and scope on AlphaBay

Illuminating the dark web market of fraudulent identity documents and personal information: An international and Australian perspective

From the beginnings of Silk Road in 2011, anonymous online marketplaces have continued to grow despite the best efforts of law enforcement. While these ever-present marketplaces remain flooded with illicit drugs and related paraphernalia, the sale and distribution of fraudulent identity documents remains a persistent problem, with these items consistently appearing for sale on both the open and dark web. While fraudulent Australian documents are some of the most popular products for sale, there is still much that is unknown about the Australian criminal market and its place within anonymous online marketplaces. Given the success of previous research in understanding the illicit drug trade through examining these marketplaces, this work examines two markets to gain an understanding of where Australian document fraud sits within this digital ecosystem. Two anonymous online marketplaces were crawled across 2020 and 2021, White House Market (WHM), and Empire Market. This data was extracted and examined to identify trends within both the international online market and the online market specifically for Australian documents, both of which have been relatively underexplored in the online space. To help illuminate the features of the market, the types of documents for sale, supply and demand trends, and trafficking flows along with vendor-related trends (e.g. product diversification and presence across markets) were examined. Each market was examined individually and then, where possible, comparisons were drawn to gain a more holistic understanding of the online fraudulent document market, with a specific focus on Australian products. Results indicate that, while the fraudulent document portion of the market is small, it is diverse, with numerous different identity-related products for sale, the most common being driver's licences from the United States (U.S.) and Australia, with digital documents dominating the whole marketplace. Overall, the most popular U.S. products were those that could be used to facilitate identity fraud, with the most popular Australian products being driver's licences and ID packs, likely linked to the presence of the 100-point identity check system used in Australia. This study demonstrates that anonymous online marketplaces have thus far been under-utilised in the study of the fraudulent document market, and that to properly understand the illicit market for fraudulent documents and personal information both the online and physical sides of the market should be considered. This information, if properly utilised, can improve the current understanding of this persistent criminal environment, building on previous research and assisting policymakers in making informed decisions.

Comparison of strength and adulteration between illicit drugs obtained from cryptomarkets versus off-line

BACKGROUND AND AIMS

Drugs sold on cryptomarkets are thought to have lower levels of adulteration and higher strength compared with those sourced off-line. The present study aimed to determine whether cryptomarket and off-line-sourced 3,4-methylenedioxy-N-methamphetamine (MDMA), cocaine, amphetamine, methamphetamine and lysergic acid diethylamide (LSD) differed in adulteration and strength.

DESIGN AND SETTING

A between-groups design was used to compare cryptomarket versus off-line-sourced drugs. Regression analyses controlling for year and service were conducted. Drug-checking services were conducted in Spain (Energy Control) and the Netherlands (Drugs Information and Monitoring System).

CASES

The cases comprised drug samples that underwent drug checking between 2016 and 2021 and were expected to contain MDMA (tablets; n = 36 065; powder: n = 6179), cocaine (n = 11 419), amphetamine (n = 6823), methamphetamine (n = 293) and LSD (n = 1817).

MEASUREMENTS

Drugs were measured for (1) matching the advertised substance (i.e. containing any amount of the expected substance); (2) strength; (3) presence of adulteration; and (4) number of adulterants.

FINDINGS

The expected drug was more likely to be identified when sourced from cryptomarkets versus off-line for MDMA tablets [adjusted odds ratio (AOR) = 2.10, 95% confidence interval (CI) = 1.28-3.43], MDMA powder (AOR = 2.64, CI = 1.55-4.51), cocaine (AOR = 3.65, CI = 1.98-6.71) and LSD (AOR = 1.75, CI = 1.13-2.72). Cryptomarket-sourced MDMA powder (β = 0.03, P = 0.012), cocaine (β = 0.08, P < 0.001) and methamphetamine (β = 0.15, P = 0.028) were statistically significantly higher in strength than substances from off-line sources. Conversely, MDMA tablets (β = -0.01, P = 0.043) and amphetamine (β = -0.07, P < 0.001) from cryptomarkets were statistically significantly lower in strength than from off-line sources. MDMA powder (AOR = 0.53, CI = 0.33-0.86) and cocaine (AOR = 0.66, CI = 0.55-0.79) were statistically significantly less likely to be adulterated if sourced from cryptomarkets. However, amphetamine (AOR = 1.54, CI = 1.25-1.90) and LSD (AOR = 1.31, CI = 1.00-1.71) were found to be more likely to be adulterated when purchased from cryptomarkets. Cocaine from cryptomarkets exhibited fewer adulterants (incidence rate ratio = 0.71, CI = 0.60-0.85).

CONCLUSION

The relationship between on-line drug market-places and substance quality varies depending on both the specific substance and the dynamics of the cryptomarket.

Criminal clickbait: a panel data analysis on the attractiveness of online advertisements offering stolen data

Introduction

Few studies have examined the sales of stolen account credentials on darkweb markets. In this study, we tested how advertisement characteristics affect the popularity of illicit online advertisements offering account credentials. Unlike previous criminological research, we take a novel approach by assessing the applicability of knowledge on regular consumer behaviours instead of theories explaining offender behaviour.

Methods

We scraped 1,565 unique advertisements offering credentials on a darkweb market. We used this panel data set to predict the simultaneous effects of the asking price, endorsement cues and title elements on advertisement popularity by estimating several hybrid panel data models.

Results

Most of our findings disconfirm our hypotheses. Asking price did not affect advertisement popularity. Endorsement cues, including vendor reputation and cumulative sales and views, had mixed and negative relationships, respectively, with advertisement popularity.

Discussion

Our results might suggest that account credentials are not simply regular products, but high-risk commodities that, paradoxically, become less attractive as they gain popularity. This study highlights the necessity of a deeper understanding of illicit online market dynamics to improve theories on illicit consumer behaviours and assist cybersecurity experts in disrupting criminal business models more effectively. We propose several avenues for future experimental research to gain further insights into these illicit processes.

Uncertainty and risk: A framework for understanding pricing in online drug markets

BACKGROUND

The pricing of illicit drugs is typically approached within the risks and prices framework. Recent sociological and economic studies of prices in online drug markets have stressed the centrality of reputation for price formation. In this paper, we propose an account of price formation that is based on the risks and prices framework, but also incorporates internal social organization to explain price variation. We assess the model empirically, and extend the current empirical literature by including payment methods and informal ranking as influences on drug pricing.

METHODS

We apply our model to estimate the prices of cannabis, cocaine, and heroin in two online drug markets, cryptomarkets (n = 92.246). Using multilevel linear regression, we assess the influence of product qualities, reputation, payment methods, and informal ranking on price formation.

RESULTS

We observe extensive quantity discounts varying across substances and countries, and find premia and discounts associated with product qualities. We find evidence of payment method price adjustment, but contrary to expectation we observe conflicting evidence concerning reputation and status. We assess the robustness of our findings concerning reputation by comparing our model to previous approaches and alternative specifications.

CONCLUSION

We contribute to an emerging economic sociological approach to the study illicit markets by developing an account of price formation that incorporates cybercrime scholarship and the risks and prices framework. We find that prices in online drug markets reflect both external institutional constraint and internal social processes that reduce uncertainty.

The success rate of online illicit drug transactions during a global pandemic

Background and Aims

In the months following the onset of the COVID-19 pandemic, the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA; 2020) observed an increased use of cryptomarkets, which led them to question whether cryptomarkets constituted a more convenient channel via which to distribute illicit drugs without any in-person contact. However, as more countries' borders closed, the likelihood is that cryptomarkets have been negatively impacted. We aim to measure and understand the success rate of transactions on cryptomarkets during the ongoing COVID-19 pandemic, through recourse to self-reported data that documents the outcome of cryptomarket transactions.

Methods

To collect self-reported data on cryptomarket transactions, we launched a platform where participants can enter information about their prior activities on cryptomarkets. The sample consists of 591 valid self-reports that were received between January 1st, 2020 and August 21st, 2020.

Results

The number of unsuccessful transactions increased concurrently with the global spread of the pandemic. Both the international and inter-continental nature of the transactions and the severity of the crisis in the vendor's country are significantly associated with delivery failure.

Conclusions

Drug cryptomarkets may have been disrupted due to the pandemic. The results lead to two opposing explanations for unsuccessful transactions. One explanation for the lower success rate is the inability of drug dealers to deliver on past promises that were made in good faith, while the second points towards opportunistic and abusive behaviour by drug dealers.

Online Black-Markets: An Investigation of a Digital Infrastructure in the Dark

This paper investigates the functioning of Online Black-Markets (OBMs), i.e. a digital infrastructure operating in the Dark Net that enables the exchange of illegal goods such as drugs, weapons and fake digital identities. OBMs exist notwithstanding adverse conditions such as police interventions, scams and market breakdowns. Relying on a longitudinal case study, we focus on the dynamics of interactions among actors and marketplace technologies and we identify three mechanisms explaining OBMs operations. In particular, we show that OBMs infrastructure is the result of commoditization, platformization and resilience processes. Our contribution relies on the identification of community-based mechanisms that generate the OBMs infrastructure, extending the current understanding of e-commerce and social commerce.

Illicit drug prices and quantity discounts: A comparison between a cryptomarket, social media, and police data

BACKGROUND

Illicit drugs are increasingly sold on cryptomarkets and on social media. Buyers and sellers perceive these online transactions as less risky than conventional street-level exchanges. Following the Risks & Prices framework, law enforcement is the largest cost component of illicit drug distribution. We examine whether prices on cryptomarkets are lower than prices on social media and prices reported by law enforcement on primarily offline markets.

METHODS

Data consists of online advertisements for illicit drugs in Sweden in 2018, scraped from the cryptomarket Flugsvamp 2.0 (n = 826) and collected with digital ethnography on Facebook (n = 446). Observations are advertisements for herbal cannabis (n = 421), cannabis resin, hash (n = 594), and cocaine (n = 257) from 156 sellers. Prices are compared with estimates from Swedish police districts (n = 53). Three multilevel linear regression models are estimated, one for each drug type, comparing price levels and discount elasticities for each platform and between sellers on each platform.

RESULTS

Price levels are similar on the two online platforms, but cocaine is slightly more expensive on social media. There are quantity discounts for all three drug types on both platforms with coefficients between -0.10 and -0.21. Despite the higher competition between sellers on cryptomarkets, prices are not lower compared to social media. Online price levels for hash and cocaine are similar to those reported by police at the 1 g level.

CONCLUSION

Mean prices and quantity discounts are similar in the two online markets. This provides support for the notion that research on cryptomarkets can also inform drug market analysis in a broader sense. Online advertisements for drugs constitute a new detailed transaction-level data source for supply-side price information for research.

Preliminary findings of the impact of COVID-19 on drugs crypto markets

BACKGROUND

The COVID-19 pandemic has had unprecedented consequences on the world economy. The impact of the pandemic on illicit drug market remains scant. We expose the potential consequences the COVID-19 pandemic could have on the ability of people who use drugs to source their illicit drugs via cryptomarkets.

METHODS

We analyzed 262 self-reported submissions of illicit drug transactions on the darkweb. The self-reports include the date of the transaction, the types of illicit drugs bought/sold, and whether the shipment of the illicit drugs succeeded, had issues (ex. unusually long delivery, an error in the type of drug shipped, quantity or concentration of the drug), or failed.

RESULTS

Between January 1st, 2020 and March 21, 2020, successful deliveries represented 60% to 100% of transactions. Starting on March 21 however, the share of shipments that had issues or failed increased rapidly and represented a majority of all shipments. At the peak of the market disruption, the successful deliveries represented only 21% of all transactions.

CONCLUSION

Illicit drug transactions on the darkweb were disrupted at the same time as lockdowns were put in place in the United States and in the United Kingdom. While no causation link can be established, the correlation suggests that lockdowns could have disrupted drug cryptomarkets activities. We discuss the market disruption in light of the literature.

New psychoactive substances on dark web markets: From deal solicitation to forensic analysis of purchased substances

The dark web scene has been drawing the attention of law enforcement agencies and researchers alike. To date, most of the published works on the dark web are based on data gained by passive observation. To gain a more contextualized perspective, a study was conducted in which three vendors were selected on the "Dream Market" dark web marketplace, from whom subsequently several new psychoactive substances (NPS) were ordered. All transactions were documented from the initial drug deal solicitation to the final qualitative analysis of all received samples. From the selected vendors, a total of nine NPS samples was obtained, all of which were analyzed by NMR, HRMS, LC-UV, and two also by x-ray diffraction. According to our analyses, four of the five substances offered under already known NPS names contained a different NPS. The selected vendors therefore either did not know about their product, or deliberately deceived the buyers. Furthermore, two of three obtained samples of purportedly novel NPS were identified as already documented substances sold under a different name. However, the third characterized substance sold as "MPF-47700" was a novel, yet uncharacterized, NPS. Finally, we received a single undeclared substance, later identified as 5F-ADB. In addition to chemical analysis of the nine obtained NPS samples, the methodology used also yielded contextual information about the accessibility of NPS on the dark web, the associated purchase process, and the modus operandi of three NPS vendors. Direct participation in dark web marketplaces seems to provide additional layers of information useful for forensic studies.

Ranking potentially harmful Tor hidden services: Illicit drugs perspective

Cryptomarkets on the dark web have emerged as a hub for the sale of illicit drugs. They have made it easier for the customers to get access to illicit drugs online while ensuring their anonymity. The easy availability of potentially harmful drugs has resulted in a significant impact on public health. Consequently, law enforcement agencies put a lot of effort and resources into shutting down online markets on the dark web. A lot of research work has also been conducted to understand the working of customers and vendors involved in the cryptomarkets that may help the law enforcement agencies. In this research, we present a ranking methodology to identify and rank top markets dealing in harmful illicit drugs. Using named entity recognition, a harm score of a drug market is calculated to indicate the degree of threat followed by the ranking of drug markets. The top-ranked markets are the ones selling the most harmful drugs. The rankings thus obtained can be helpful to law enforcement agencies by locating specific markets selling harmful illicit drugs and their further monitoring.

Interpol review of controlled substances 2016-2019

This review paper covers the forensic-relevant literature in controlled substances from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Reputation transferability across contexts: Maintaining cooperation among anonymous cryptomarket actors when moving between markets

BACKGROUND

Buyers and sellers of illegal drugs in cryptomarkets have been found to overcome trust issues created by anonymity and the lack of legal protection with the help of reputation systems. Cryptomarkets rarely operate for longer than a year before closing or getting shut down due to external shocks, such as law enforcement operations. This results in large flows of users migrating between market platforms. An important question in order to better understand why cryptomarkets recover quickly after external shocks is: to what extent can reputation be carried over between different markets? This problem is non-trivial given the anonymity of cryptomarket users and the fact that reputation is tied to a user's online identity. Here we analyze conditions under which sellers choose to migrate with the same identity and whether reputation history from previous cryptomarkets yields benefits in new contexts.

METHODS

We analyze sellers' migration in three cryptomarkets (Abraxas, Agora and AlphaBay) and follow their reputation history by linking user accounts between marketplaces using the Grams database. We use longitudinal multi-level regression models to compare market success of migrant and non-migrant sellers. In total, the data contains more than 7,500 seller account and 2.5 million buyers' reputational feedback messages over a period of 3 years.

FINDINGS

It is predominantly the successful sellers with a large number of sales and high reputation who choose to migrate and maintain their identity using cryptographic methods after market closures. We find that reputation history from previous markets creates a competitive advantage to migrant sellers compared to market entrants.

CONCLUSION

Reputation transferability embeds cryptomarket users beyond a single market platform, which incentivizes cooperative behavior. The results also suggest that reputation transferability might contribute to a quick recovery of online drug trade after shutdowns and accumulation of market share in the hands of a small fraction of successful sellers.

An evidence synthesis of strategies, enablers and barriers for keeping secrets online regarding the procurement and supply of illicit drugs

This systematic review attempts to understand how people keep secrets online, and in particular how people use the internet when engaging in covert behaviours and activities regarding the procurement and supply of illicit drugs. With the Internet and social media being part of everyday life for most people in western and non-western countries, there are ever-growing opportunities for individuals to engage in covert behaviours and activities online that may be considered illegal or unethical. A search strategy using Medical Subject Headings terms and relevant key words was developed. A comprehensive literature search of published and unpublished studies in electronic databases was conducted. Additional studies were identified from reference lists of previous studies and (systematic) reviews that had similar objectives as this search, and were included if they fulfilled our inclusion criteria. Two researchers independently screened abstracts and full-texts for study eligibility and evaluated the quality of included studies. Disagreements were resolved by a consensus procedure. The systematic review includes 33 qualitative studies and one cross-sectional study, published between 2006 and 2018. Five covert behaviours were identified: the use of communication channels; anonymity; visibility reduction; limited posts in public; following forum rules and recommendations. The same technologies that provide individuals with easy access to information, such as social networking sites and forums, digital devices, digital tools and services, also increase the prevalence of inaccurate information, loss of privacy, identity theft and disinhibited communication. This review takes a rigorous interdisciplinary approach to synthesising knowledge on the strategies adopted by people in keeping secrets online. Whilst the focus is on the procurement and supply of illicit drugs, this knowledge is transferrable to a range of contexts where people keep secrets online. It has particular significance for those who design online/social media applications, and for law enforcement and security agencies.

An insight into the sale of prescription drugs and medicine on the AlphaBay cryptomarket

Internet access has provided new ways to trade goods. Unlike conventional legal sale sites, cryptomarkets facilitate exchanges in a context where the anonymity of participants is warranted. The aim of this article was to obtain a better understanding of the trafficking of prescription drugs and medicine on the AlphaBay cryptomarket. The results showed that alprazolam, oxycodone, and Adderall were the most offered prescription drugs while alprazolam, diazepam, and oxycodone were the most sold substances. The sale was dominated by North America, Australia, and Western European countries. The revenue of prescription drugs was estimated to be more than US$65 million since the creation of AlphaBay, a small market in comparison with the worldwide legal pharmaceutical market’s estimate of US$1.3 trillion in 2020. Digital traces offer a complementary way to understand the trafficking of prescription drugs and medicine and to identify the most prolific vendors and their implication in this trafficking.

Sellers' risk perceptions in public and private social media drug markets

INTRODUCTION

From the early use of pagers and cellular phones to the darknet and smartphones, technological developments have facilitated drug deals in various ways, especially by altering time and space boundaries. Traditional drug market literature theorises about how physical markets, within which sellers act according to their risk perceptions and motivation, are led by supply, demand, and enforcement. However, there is an almost absolute research gap in understanding how this relates to digital markets and social media markets in particular. It is expected that the plasticity of technology makes digital markets highly mouldable so that the sellers are able to shape markets according to their use.

RESEARCH AIM

The aim of the study is to describe and understand drug dealing on social media within the structure of existing markets. We aim to do so by analysing how drug sellers' risk perceptions and motivations form and are formed by social media technology.

METHODS

We conducted a three-month digital ethnographic study on Facebook and Instagram in the five Nordic countries (Denmark, Finland, Iceland, Norway, and Sweden), as well as 107 semi-structured qualitative interviews with sellers (2/3 of the sample) and buyers (1/3 of the sample) using online markets within the same countries.

RESULTS

Drug dealing on social media varies according to the structure of the chosen media and users' risk perceptions and motivations. Two market forms are suggested: 1) public digital markets (e.g., Facebook groups and Instagram) allow sellers to expand their customer lists, but the risk is quite high, while 2) private digital markets are based on one-on-one communication and demand greater knowledge but are perceived as more secure. Sellers choose which media to use and how to use them based on perceived risk and, therefore, have a significant impact on the formation of social media drug markets.

Should we smoke it for you as well? An ethnographic analysis of a drug cryptomarket environment

INTRODUCTION

Why aren't cryptomarkets more widely used? Researchers from a wide array of fields have attempted to answer this question by studying the size of drug cryptomarkets, the substances trafficked, and their structure. In this paper we address the potential acceptance of drug cryptomarkets by studying their perceived ease of use.

METHODS

This paper draws on observational data collected over 350 h of unstructured observation during an ethnographic study conducted in April-September 2016 of the two most prominent drug cryptomarkets at the time, in addition to seven face-to-face semi-structured qualitative interviews.

ANALYSIS

Use of cryptomarkets relies on specialised knowledge. The administrators of the cryptomarkets do not play a publicly visible role in facilitating or easing cryptomarket use while simultaneously expecting cryptomarket users to exhibit self-reliance. We argue that the current levels of complexity and obfuscation constructed in the cryptomarket environment act as a barrier to the widespread acceptance of this technology.

DISCUSSION

Through studying cryptomarkets' potential for widespread use we have shed light on current barriers to their growth requirement of specialised knowledge in order to use cryptomarkets and no public efforts to bridge the knowledge gap on behalf of cryptomarket administrators. As cryptomarkets continue to develop the ease of use of these platforms are bound to change, and with them the likelihood that cryptomarket usage may increase.

Nonmedical prescription psychiatric drug use and the darknet: A cryptomarket analysis

Background

Nonmedical prescription psychiatric drug use (NMPDU) is an increasing global health problem, with recent concern focusing on darknet cryptomarkets as sources of procurement. There is a shortage of evidence regarding comparative worldwide NMPDU trends, due in part to data collection difficulties. This problem is particularly marked for non-opioid drugs, particularly those psychiatric drugs which act on the central nervous system (CNS) and have high misuse potential and are associated with high levels of dependency and fatal overdose. This paper therefore has two goals: 1) to report on the kinds of psychiatric prescription drugs available on cryptomarkets, and 2) to use this data to uncover temporal and geographical trends in sales of these products, potentially informing policy regarding NMPDU more generally.

Method

Digital trace data collected from 31 cryptomarkets in operation between September 2013 and July 2016 was analysed by country of origin descriptively and for trends in the sales for 7 psychiatric drug groupings, based on their main indication or intended use in psychiatric practice.

Results

Sedatives (such as diazepam and alprazolam) and CNS stimulants (mainly Adderall, modafinil and methylphenidate) had the greatest share of sales, but usage and trends varied by location. The UK has high and rising levels of sedative sales, whilst the USA has the greatest stimulant sales and increasing sedative rates. Sales of drugs used in the treatment of opioid dependency are also substantial in the USA. The picture is less clear in mainland Europe with high sales levels reported in unexpected Central and Northern European countries. There is evidence of a move towards the more potent sedative alprazolam – already implicated as a source of problematic NMPDU in the USA – in Australia and the UK. Sales of drugs such as antidepressants, antipsychotics, mood stabilisers and antidementia drugs – all drugs with limited abuse potential – were negligible, indicating minimal levels of online cryptomarket procurement for self-medicating mental health problems.

Conclusion

Predominantly, psychiatric drugs with potent sedative, stimulant or euphoriant effects are sold on cryptomarkets and this varies by country. With some caveats regarding the limitations of cryptomarket digital trace data taken into account, the study of trends of these products sold online over time may offer a novel and increasingly important window onto wider drug purchasing habits.

Effect of restricting the legal supply of prescription opioids on buying through online illicit marketplaces: interrupted time series analysis

OBJECTIVE

To examine the effect on the trade in opioids through online illicit markets ("cryptomarkets") of the US Drug Enforcement Administration's ruling in 2014 to reschedule hydrocodone combination products.

DESIGN

Interrupted time series analysis.

SETTING

31 of the world's largest cryptomarkets operating from October 2013 to July 2016.

MAIN OUTCOME MEASURES

The proportion of total transactions, advertised and active listings for prescription opioids, prescription sedatives, prescription steroids, prescription stimulants, and illicit opioids, and the composition of the prescription opioid market between the US and elsewhere.

RESULTS

The sale of prescription opioids through US cryptomarkets increased after the schedule change, with no statistically significant changes in sales of prescription sedatives, prescription steroids, prescription stimulants, or illicit opioids. In July 2016 sales of opioids through US cryptomarkets represented 13.7% of all drug sales (95% confidence interval 11.5% to 16.0%) compared with a modelled estimate of 6.7% of all sales (3.7% to 9.6%) had the new schedule not been introduced. This corresponds to a 4 percentage point yearly increase in the amount of trade that prescription opioids represent in the US market, set against no corresponding changes for comparable products or for prescription opioids sold outside the US. This change was first observed for sales, and later observed for product availability. There was also a change in the composition of the prescription opioid market: fentanyl was the least purchased product during July to September 2014, then the second most frequently purchased by July 2016.

CONCLUSIONS

The scheduling change in hydrocodone combination products coincided with a statistically significant, sustained increase in illicit trading of opioids through online US cryptomarkets. These changes were not observed for other drug groups or in other countries. A subsequent move was observed towards the purchase of more potent forms of prescription opioids, particularly oxycodone and fentanyl.