Improvements in Toxicology Testing to Identify Fentanyl Analogs and Other Novel Synthetic Opioids in Fatal Drug Overdoses, Connecticut, January 2016–June 2019

Abstract

Objectives

Drug overdose deaths in Connecticut increasingly involve a growing number of fentanyl analogs and other novel nonfentanyl synthetic opioids (ie, novel synthetics). Current postmortem toxicology testing methods often lack the sophistication needed to detect these compounds. We examined how improved toxicology testing of fatal drug overdoses can determine the prevalence and rapidly evolving trends of novel synthetics.

Methods

From 2016 to June 2019, the Connecticut Office of the Chief Medical Examiner increased its scope of toxicology testing of suspected drug overdose deaths in Connecticut from basic to enhanced toxicology testing to detect novel synthetics. The toxicology laboratory also expanded its testing panels during this time. We analyzed toxicology results to identify and quantify the involvement of novel synthetics over time.

Results

From 2016 to June 2019, 3204 drug overdose deaths received enhanced toxicology testing; novel synthetics were detected in 174 (5.4%) instances. Ten different novel synthetics were detected with 205 total occurrences. Of 174 overdose deaths with a novel synthetic detected, most had 1 (n = 146, 83.9%) or 2 (n = 26, 14.9%) novel synthetics detected, with a maximum of 4 novel synthetics detected. Para-fluorobutyrylfentanyl/FIBF, furanylfentanyl, and U-47700 were most identified overall, but specific novel synthetics came in and out of prominence during the study period, and the variety of novel synthetics detected changed from year to year.

Conclusions

Enhanced toxicology testing for drug overdose deaths is effective in detecting novel synthetics that are not identified through basic toxicology testing. Identifying emerging novel synthetics allows for a timely and focused response to potential drug outbreaks and illustrates the changing drug market.

Fentanyl and fentanyl analogs have increasingly been implicated in drug overdose deaths in the United States. ^{1 -4} Connecticut is at particular risk for a proliferation of fentanyl, fentanyl analog, or other illicit opioid-derivative overdose deaths: in 2016, rates of opioid-involved overdose deaths in Connecticut surpassed national rates, and most overdose deaths involved illicit opioids. ⁵ In 2019, fentanyl and fentanyl analogs accounted for 82% of drug overdose deaths in Connecticut, up from 26% in 2015. ⁶ The number of fatal overdoses involving novel synthetic opioids and “designer opioids,” such as U-47700, AH-7921, and MT-45, also increased nationally. ^4,7,8 Fentanyl analogs and other nonfentanyl synthetic opioids are concerning because they often have higher potencies and pose a greater risk for overdose than other opioids. ^9,10

In 2013, fentanyl analogs first appeared on the illicit drug market with acetyl fentanyl and expanded quickly in subsequent years. ^1,11,12 Other novel synthetic opioids followed a similar pattern of emergence as recreational drugs. ¹³ These compounds are manufactured illicitly and can be difficult to control and regulate. ¹³ Small changes in chemical structures allow for a nearly limitless production of different analogs. ¹ The drug market continues to evolve as new fentanyl analogs and other novel synthetic opioids rapidly emerge. ^{3,7,13 -16}

The surge in various novel synthetic opioid derivatives adds a layer of complexity to forensic investigation casework. ¹⁴ More specific and sensitive toxicology testing equipment and analytical methods are needed to detect and distinguish the growing number of fentanyl analogs and other novel synthetic opioids. ^4,15 Despite the structural and pharmacologic similarities among fentanyl analogs, the small variations make detection of these compounds difficult because specialized testing capabilities are needed. ^2,9 The rapid emergence of new compounds presents an additional challenge as forensic scientists work to keep up with the ever-changing drug landscape. ^4,14 Supplemental Enhanced State Opioid Overdose Surveillance (ESOOS) funding from the Centers for Disease Control and Prevention (CDC) for enhanced toxicology testing enabled Connecticut to test for designer opioids, particularly fentanyl analogs.

This study examined how enhanced forensic toxicology testing can determine the prevalence and evolving trends of fentanyl analogs and other novel synthetic opioids in fatal drug overdoses. Before implementation of enhanced toxicology testing, the involvement of fentanyl analogs and other novel synthetic opioids in drug overdose deaths was not known in Connecticut, because these substances were not detected by basic toxicology testing methods. Tracking the rapidly changing illicit opioid market is important in designing innovative prevention efforts to reduce the incidence of opioid overdose deaths. This study examined the effectiveness of enhanced toxicology testing in detecting these emerging compounds and may serve as a model for other medical examiners’ and coroners’ offices to respond to drug overdose outbreaks and surveil the shifting drug market in a timely manner.

Methods

In 2017, the Connecticut Department of Public Health (CT DPH) received supplemental funding through an ESOOS cooperative agreement from CDC. CT DPH provided funding to the Connecticut Office of the Chief Medical Examiner (CT OCME) to support enhancements to toxicology testing of fatal drug overdoses to detect novel and emerging fentanyl analogs and other novel synthetic opioids. CT OCME applied these funds to increase its depth and scope of toxicology testing by upgrading from basic testing panels with limited compounds to more complex and comprehensive expanded toxicology testing panels.

Expanded testing panels included up to 14 fentanyl analogs and other novel synthetic opioid derivatives and more than 200 other compounds. CT OCME ordered supplemental specialized directed testing on a case-by-case basis to confirm the detection of certain atypical compounds that were not included in the expanded screen. CT OCME requested additional designer opioid tests as needed for the express purpose of identifying up to 21 fentanyl analogs and other novel synthetic opioids. We used the term enhanced toxicology testing to include all expanded testing panels, designer opioid testing panels, and any other currently available specialized directed testing to precisely identify fentanyl analogs or other novel synthetic opioids.

CT OCME ordered routine drug screening on all suspected drug overdose deaths that its office investigated. NMS Labs (Horsham, Pennsylvania) performed toxicology testing on blood, tissue, fluid, serum/plasma, and/or urine samples from suspected drug overdose deaths using high-performance liquid chromatography/time of flight–mass spectrometry and high-performance liquid chromatography/tandem mass spectrometry analytical methods. Throughout the toxicology testing period, NMS Labs regularly updated its testing panels to reflect the most current and newly emerging compounds. ¹⁷ Consequently, the scope of toxicology testing panels shifted over time as NMS Labs added or removed different compounds, resulting in an evolving array of fentanyl analog and other novel synthetic opioid analytes.

The current list of fentanyl analogs and other novel synthetic opioids tested included 3-methylmethoxyacetylfentanyl, 4-ANPP (despropionyl fentanyl), 4-methylmethoxyacetylfentanyl, acetyl fentanyl, acryl fentanyl, butyrylfentanyl, carfentanil, cis-3-methylfentanyl, cyclopropylfentanyl, furanylfentanyl, isobutyrylfentanyl, methoxyacetylfentanyl, ortho-fluorofentanyl, para-fluorobutyrylfentanyl, para-fluorofentanyl, para-fluoroisobutyrylfentanyl (FIBF), THF-F, trans-3-methylfentanyl, U-47700, U-49900, U-51754, and valeryl fentanyl.

We analyzed toxicology data on all unintentional drug overdose deaths occurring in Connecticut from January 1, 2016, through June 30, 2019. Beginning in 2017, ESOOS funding supported the increased use of enhanced toxicology testing. CT OCME ordered retrospective enhanced toxicology testing on all 2017 deaths and a selection of 2016 deaths when the presence of a fentanyl analog or other novel synthetic opioid was suggested but required specialized testing to confirm its presence. Most (96%) samples tested were blood samples, and the remaining 4% were a combination of tissue, fluid, serum/plasma, and urine samples. Delayed overdose deaths in which blood or urine samples from hospital admission were unavailable did not undergo postmortem toxicology testing. In those instances, CT OCME certified the drug overdose deaths based on circumstances, hospital toxicology testing, and/or testing of drug samples at the scene.

We analyzed toxicology results to identify and quantify the involvement of fentanyl analogs and other novel nonfentanyl synthetic opioids (ie, novel synthetics). We excluded fentanyl itself and acetyl fentanyl from the novel synthetics definition because NMS Labs added both to the basic toxicology scope of testing due to their common presence in postmortem samples. We also excluded the compound 4-ANPP from the definition of novel synthetics because it is a metabolite of fentanyl and several fentanyl analogs as well as an intermediate compound generated in the manufacture of fentanyl. ⁹ Therefore, the presence of 4-ANPP could not definitively indicate the involvement of fentanyl analogs. ³ Our study did not require institutional review board approval by the CT DPH Human Investigations Committee because it did not involve human subjects research.

Statistical Analysis

We calculated descriptive statistics using univariate analyses to quantify the frequency and percentage of novel synthetic overdose deaths, overall and by year, for each compound detected. We also graphed the distribution of novel synthetic deaths by date of death and by compound to visualize how the array of novel synthetics evolved over time.

Results

From January 1, 2016, through June 30, 2019, CT OCME certified 3535 unintentional (accidental) drug overdose deaths that occurred in Connecticut. CT OCME ordered postmortem toxicology testing in 97.7% (n = 3453) of those deaths (Table). Toxicology testing was high throughout the study period, ranging from 97.5% (908 of 931) in 2016 to 98.2% (540 of 550) in the first half of 2019. CT OCME ordered enhanced toxicology testing on 92.8% (3204 of 3453) of deaths that underwent any postmortem toxicology testing. The percentage of drug overdose deaths that received enhanced toxicology testing increased during the study period: 77.3% (702 of 908) in 2016, 96.8% (977 of 1009) in 2017, 99.0% (986 of 996) in 2018, and 99.8% (539 of 540) in the first half of 2019.

Table.

Unintentional drug overdose deaths with novel synthetics detected, by year, Connecticut, January 1, 2016, through June 30, 2019 ^a

Variable	January 1 to December 31, 2016	January 1 to December 31, 2017	January 1 to December 31, 2018	January 1 to June 30, 2019	Total
All drug overdoses, no.	931	1033	1021	550	3535
Any toxicology testing	908 (97.5)	1009 (97.7)	996 (97.6)	540 (98.2)	3453 (97.7)
Enhanced toxicology testing b	702 (77.3)	977 (96.8)	986 (99.0)	539 (99.8)	3204 (92.8)
Any novel synthetic c	29 (4.1)	81 (8.3)	54 (5.5)	10 (1.9)	174 (5.4)
Acryl fentanyl	0	5 (0.5)	0	0	5 (0.2)
Butyryl/isobutyrylfentanyl d	0	8 (0.8)	1 (0.1)	1 (0.2)	10 (0.3)
Carfentanil	0	9 (0.9)	0	0	9 (0.3)
Cyclopropylfentanyl	0	5 (0.5)	1 (0.1)	0	6 (0.2)
Furanylfentanyl	17 (2.4)	25 (2.6)	0	0	42 (1.3)
Methoxyacetylfentanyl	0	4 (0.4)	6 (0.6)	0	10 (0.3)
para-Fluorobutyrylfentanyl/FIBF d	3 (0.4)	28 (2.9)	40 (4.1)	6 (1.1)	77 (2.4)
para-Fluorofentanyl	0	1 (0.1)	0	0	1 (<0.1)
U-47700	12 (1.7)	21 (2.1)	3 (0.3)	0	36 (1.1)
Valeryl fentanyl	0	0	6 (0.6)	3 (0.6)	9 (0.3)

^aAll values are number (percentage) unless otherwise indicated.

^bEnhanced toxicology testing includes all expanded testing panels, designer opioid testing panels, and any other currently available specialized directed testing to precisely identify fentanyl analogs or other novel nonfentanyl synthetic opioids.

^cAny novel synthetic includes fentanyl analogs and other novel nonfentanyl synthetic opioids. Fentanyl, acetyl fentanyl, and 4-ANPP are excluded from the definition.

^dThe toxicology tests cannot distinguish between isomers butyrylfentanyl and isobutyrylfentanyl and isomers para-fluorobutyrylfentanyl and para-fluoroisobutyrylfentanyl (FIBF), so they were reported together as butyryl/isobutyrylfentanyl and para-fluorobutyrylfentanyl/FIBF, respectively.

Enhanced toxicology testing identified at least 1 novel synthetic compound in 5.4% (174 of 3204) of drug overdose deaths during the study period (Table). The percentage of deaths involving novel synthetics doubled from 4.1% (29 of 702) in 2016 to 8.3% (81 of 977) in 2017, then decreased to 5.5% (54 of 986) in 2018 and 1.9% (10 of 539) in the first half of 2019.

Of the 174 identified novel synthetic deaths, most had 1 (n = 146, 83.9%) or 2 (n = 26, 14.9%) different novel synthetics detected; 1 (0.6%) death had 3 novel synthetics detected and 1 (0.6%) death had 4 novel synthetics detected. Enhanced toxicology testing identified 10 different novel synthetics with 205 total occurrences. Overall, enhanced toxicology testing identified para-fluorobutyrylfentanyl/FIBF, furanylfentanyl, and U-47700 as the most common novel synthetics (Table).

The array of identified novel synthetics evolved over time, with specific compounds sporadically coming in and out of prominence (Figure). For example, enhanced toxicology testing detected furanylfentanyl, U-47700, and para-fluorobutyrylfentanyl/FIBF in 2016, but furanylfentanyl and U-47700 disappeared by mid-2018. Para-fluorobutyrylfentanyl/FIBF persisted throughout the study period. During 2017, acryl fentanyl, butyryl/isobutyrylfentanyl, para-fluorofentanyl, carfentanil, cyclopropylfentanyl, and methoxyacetylfentanyl emerged, but only butyryl/isobutyrylfentanyl, cyclopropylfentanyl, and methoxyacetylfentanyl sustained and continued to be detected after December 2017. Valeryl fentanyl did not appear until the second half of 2018 but continued to be identified through June 2019.

Figure.

Number of unintentional drug overdose deaths with novel synthetics detected, by date of death, Connecticut, January 2016–June 2019.

The frequency of various novel synthetics shifted from year to year (Figure). In 2016, enhanced toxicology testing detected only 3 different novel synthetics (furanylfentanyl, U-47700, and para-fluorobutyrylfentanyl/FIBF), and furanylfentanyl was the most common occurrence. During 2017, enhanced toxicology testing detected 9 different novel synthetics and identified para-fluorobutyrylfentanyl/FIBF as the most frequent, followed closely by furanylfentanyl and U-47700. In 2018, the number of different novel synthetics fell to 6, but para-fluorobutyrylfentanyl/FIBF still predominated. Enhanced toxicology testing detected para-fluorobutyrylfentanyl/FIBF in 4.1% (40 of 986) of drug overdose deaths in 2018, resulting in the highest percentage of any novel synthetic in any single year. From January through June 2019, enhanced toxicology testing identified only 3 different novel synthetics, of which para-fluorobutyrylfentanyl/FIBF was the most common.

Discussion

Enhanced toxicology testing allowed CT DPH to identify and analyze overdose deaths involving novel synthetics and related trends over time. Throughout the study period, enhanced toxicology testing identified at least 1 novel synthetic in about 5% of drug overdose deaths with enhanced toxicology testing. This finding is consistent with data from another study in which <5% of opioid-involved overdose deaths involved a fentanyl analog other than acetylfentanyl. ¹⁸ In Connecticut, the percentage of deaths involving novel synthetics jumped more than 100% from 2016 to 2017. During the same time frame, the percentage of fatal drug overdoses that received enhanced toxicology testing rose by 25%. A portion of the surge in novel synthetic–involved overdose deaths during this period could be attributed to the enhanced toxicology screening. As enhanced toxicology testing became more routine over time, the identification of novel synthetics in postmortem samples was likely to grow in tandem. However, the rapid increase in novel synthetic–involved overdose deaths in 2017 corresponded with similar national trends. According to the National Forensic Laboratory Information System, the number of drug submissions testing positive for fentanyl analogs and illicit synthetic opioids increased sharply from January to June 2017. ¹⁹ These results highlight the utility of widespread enhanced toxicology testing to accurately examine and quantify fatal novel synthetic overdoses. Without additional testing, basic toxicology testing alone would fail to identify these compounds.

Following an apparent peak in 2017, novel synthetic deaths in Connecticut trended downward from 2017 through June 2019. Given the high adherence to enhanced toxicology testing for fatal drug overdoses by 2017, the seeming decline likely represents a true decrease in the prevalence of novel synthetics in overdose deaths. This trend mirrored data from the State Unintentional Drug Overdose Reporting System that showed a 19% decline in fentanyl analog–involved overdose deaths from the second half of 2017 to the first half of 2018. ²⁰ Given that fentanyl-related compounds and other novel synthetic opioids primarily originate in China, these apparent decreases in novel synthetic–involved overdose deaths may be driven in part by regulatory efforts from China to schedule fentanyl analogs and fentanyl-related substances under national control. ²¹ In March 2017, China’s National Narcotics Control Commission announced the addition of carfentanil, furanylfentanyl, acryl fentanyl, and valeryl fentanyl to the list of regulated substances, with additional fentanyl-related compounds added in August 2018. ²² In April 2019, China placed fentanyl-related substances under class-wide control. ²¹

This study also identified the evolving dynamics of specific novel synthetic compounds in the local drug market. By analyzing toxicology results, CT DPH observed the proliferation of para-fluorobutyrylfentanyl/FIBF and the rise and fall of furanylfentanyl and U-47700. A study of opioid-involved overdose deaths in 28 states noted similar fluctuations among various fentanyl analogs, including carfentanil, furanylfentanyl, cyclopropylfentanyl, and acryl fentanyl, from July 2016 to December 2018. ¹⁸ Access to these data on a concentrated and local level allows for a highly targeted and timely response to perceived spikes in drug overdoses. These findings further reflect the need to routinely perform enhanced toxicology testing on all suspected fatal and nonfatal drug overdoses. A lack of consistent testing hampers any ability to precisely track drug outbreaks or declines. Our results demonstrated how local trends can differ from what other states or areas of the country experience. For example, carfentanil sparked nationwide concern after outbreaks in states such as Florida and Ohio in 2016. ²³ However, it did not emerge as a major threat in Connecticut, where only 9 carfentanil deaths occurred in 2017, with no other such deaths identified during the study period.

The availability of accurate and reliable data is crucial to the development of effective public health strategies and interventions to reduce the incidence of drug overdoses. Morrow et al ²⁴ drew similar conclusions and remarked that early communication of the detection of novel synthetic opioids through toxicology testing can substantially affect the successful deployment of intervention and treatment response efforts. We recommend that all suspected drug overdose deaths receive enhanced toxicology testing to detect novel synthetic opioids and to share these data with local authorities to remain apprised of emerging substances. Not only can these data illustrate potential drug outbreaks, but knowing the specific compounds that cause an increase in fatal overdoses can inform engagement of appropriate harm reduction strategies. ²³  For example, an outbreak of a fentanyl analog may necessitate the use of multiple doses of naloxone to reverse an overdose, because fentanyl analogs often have higher potencies than other opioids do. ¹⁴ The deployment of additional naloxone kits to affected communities would consequently be essential to save lives.

This study provides a framework that other public health agencies can use to help inform timely responses to potential drug outbreaks to prevent overdoses in communities. Adopting enhanced toxicology testing instead of basic testing for all fatal suspected drug overdoses as standard practice can enable medical examiners’ and coroners’ offices to improve the quality of fatal fentanyl analog and other novel synthetic opioid overdose classification. Successful implementation of an enhanced toxicology testing protocol and subsequent data sharing depend on maintaining a close working relationship with medical examiners’ and coroners’ offices. Connecticut is uniquely positioned in that it has a centralized medical examiner’s office, making collaboration easily accessible. Executing a formal memorandum of agreement between the public health and medical examiner agencies was crucial to establish the necessary partnership and allocate the ESOOS grant funding to support enhanced testing.

In Connecticut, we easily accomplished the implementation of enhanced toxicology testing at the medical examiner’s office. Because CT OCME outsources toxicology testing to an accredited forensic toxicology laboratory, it was simply a matter of ordering an expanded testing panel. Using the private laboratory instead of the former in-house laboratory allowed CT OCME to improve turnaround time, improve the scope of testing, and cut toxicology costs in half. Other offices with in-house testing may consider sending their toxicology samples for suspected drug overdose deaths to a private laboratory for this specialized testing. In most instances, using the full expanded testing panel on one case sample is more cost-effective than ordering directed testing for specific substances.

Limitations

This study had several limitations. First, because of funding limitations when this project first began, only a portion of fatal drug overdoses that occurred in 2016 underwent enhanced toxicology testing, which likely resulted in an underestimation of novel synthetic deaths in 2016. Second, this study analyzed data from a single state and may not be representative of trends seen in other states or localities. Third, given the rapid and constant emergence of novel synthetic compounds, specific compounds may have gone undetected either because the compound was unknown at the time or validated testing methods were not yet developed or available. However, NMS Labs regularly updated their testing panels throughout the study period with the most relevant new and current fentanyl analogs and other novel synthetic opioids. Finally, this study was limited to the analysis of toxicology results from fatal drug overdoses, which represent only a small portion of the full opioid crisis. Efforts to expand toxicology testing of samples from nonfatal overdoses to identify novel synthetics would provide a more complete picture of potential opioid outbreaks.

Conclusions

Identifying novel synthetics in the illicit drug market is essential, as novel synthetics are often more potent than fentanyl or other opioid drugs and, therefore, pose a heightened risk for overdose. Adopting more advanced postmortem toxicology testing methods as standard practice can be an effective way to detect these compounds that most basic methods do not. Surveillance and tracking of these novel synthetics and the rapidly changing illicit opioid market are important to better inform communities and guide prevention work to reduce opioid-involved overdoses.

ORCID iD

Heather A. Clinton, BS https://orcid.org/0000-0002-6384-4070