High concentrations of illicit stimulants and cutting agents cause false positives on fentanyl test strips - PubMed (original) (raw)

High concentrations of illicit stimulants and cutting agents cause false positives on fentanyl test strips

Tracy-Lynn E Lockwood et al. Harm Reduct J. 2021.

Abstract

Background: The opioid epidemic has caused an increase in overdose deaths which can be attributed to fentanyl combined with various illicit substances. Drug checking programs have been started by many harm reduction groups to provide tools for users to determine the composition of their street drugs. Immunoassay fentanyl test strips (FTS) allow users to test drugs for fentanyl by either filling a baggie or cooker with water to dissolve the sample and test. The antibody used in FTS is very selective for fentanyl at high dilutions, a characteristic of the traditional use of urine testing. These street sample preparation methods can lead to mg/mL concentrations of several potential interferents. We tested whether these concentrated samples could cause false positive results on a FTS.

Methods: 20 ng/mL Rapid Response FTS were obtained from BTNX Inc. and tested against 4 different pharmaceuticals (diphenhydramine, alprazolam, gabapentin, and naloxone buprenorphine) and 3 illicit stimulants [cocaine HCl, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA)] in concentrations from 20 to 0.2 mg/mL. The FTS testing pad is divided into 2 sections: the control area and the test area. Control and test area signal intensities were quantified by ImageJ from photographs of the test strips and compared to a threshold set by fentanyl at the FTS limit of detection.

Results: False positive results indicating the presence of fentanyl were obtained from samples of methamphetamine, MDMA, and diphenhydramine at concentrations at or above 1 mg/mL. Diphenhydramine is a common cutting agent in heroin. The street sample preparation protocols for FTS use suggested by many online resources would produce such concentrations of these materials. Street samples need to be diluted more significantly to avoid interference from potential cutting agents and stimulants.

Conclusions: Fentanyl test strips are commercially available, successful at detecting fentanyl to the specified limit of detection and can be a valuable tool for harm reduction efforts. Users should be aware that when drugs and adulterants are in high concentrations, FTS can give a false positive result.

Keywords: Drug testing; False positives; Fentanyl; Fentanyl test strip (FTS); Harm reduction; Opioid; Stimulant.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1

Fig. 1

FTS with fentanyl standard: FTS ran with fentanyl standard at 125 ng/mL (a), 100 ng/mL (b), 83 ng/mL (c), 63 ng/mL (d), 50 ng/mL (e), 25 ng/mL (f), and 5 ng/mL (g). Fentanyl threshold line determined to be at 25 ng/mL correlating to 1152 counts (SD = 72)

Fig. 2

Fig. 2

Fentanyl test strip images of interference compounds: FTS were ran with water, cocaine, methamphetamine, MDMA, diphenhydramine capsules, and diphenhydramine tablets and were photographed after 5 min. The testing bar (right side of testing pad) for moderately concentrated samples (approximately > 2 mg/mL) of methamphetamine, MDMA, diphenhydramine capsules, diphenhydramine tablets did not appear indicating false positives

Fig. 3

Fig. 3

Illicit stimulants, fillers, and blanks: samples with intensities below the red line are likely to be mistaken for fentanyl. Sub-graphs for each substance that crosses the fentanyl threshold line are included with error bars for multiple measurements

Fig. 4

Fig. 4

Color development of control and test bars for water and fentanyl: A–J: Water, Panels a–j: 1 mg/mL Fentanyl standard. A/a: testing pad prior to solution saturation; Panel B/b, 10 s after solution reached testing pad; Panel C/c, 20 s; Panel D/d, 30 s, Panel E/e, 40 s; Panel F/f, 50 s; Panel G/g, 60 s; Panel H/h, 120 s; Panel I/i, 240 s, Panel J/j, 420 s

Fig. 5

Fig. 5

Development time for fentanyl test strip control and test bars: FTS were tested in DI water and 1 mg/mL fentanyl standard. Photographs were taken every 5 s of test strips up to 420 s. The integrated intensities of the control and test bars were analyzed using ImageJ

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References

    1. National Institue of Health. Opioid Overdose Crisis. 2020. p. 1–3.
    1. Centers for Disease Control and Prevention. Opioid Overdose Data Overview. 2018;1–2.
    1. Centers for Disease Control and Prevention. Understanding the epidemic: the three waves of opioid overdose deaths, combatting the opioid overdose epidemic (Internet). 2020. p. 1–4. https://www.cdc.gov/drugoverdose/epidemic/index.html.
    1. Hedegaard H, Miniño AM, Warner M. Drug overdose deaths in the United States, 1999–2018. NCHS Data Brief. 2020;356:1–8. - PubMed
    1. Hedegaard H, Bastian BA, Trinidad JP, Spencer MR, Warner M. Regional differences in the drugs most frequently involved in drug overdose deaths: United states, 2017. Natl Vital Stat Rep. 2019;68(12):1–15. - PubMed

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