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September 2020

Case Summary: Preliminary Positive but Confirmation Negative - Suspected Designer Benzodiazepine Use in a Patient Maintained on SC Buprenorphine

This case features a patient with combined opioid and sedative use disorder who has stabilized on buprenorphine without opioid use for years but has continued to use benzodiazepines and other sedatives. With the increasing availability of "pressed 'Xanax'”, which include various synthetic benzodiazepines ordered from overseas through the internet, he has had ready access to illicit benzodiazepine supply. Additionally, he did much better in person compared to the use of virtual meetings and phone/telemedicine counseling, often missing sessions or having “'connection' problems”.

Urine toxicology testing results:


Figure 1: "see below" represents a preliminary positive result (done via immunoassay type test)


Figure 2: Benzodiazepine Confirmation Panel (done via chromatography either GC or LC combined with mass spectroscopy (MS))


Figure 3: This table shows the frequency of preliminary positive "see below" results

Frequently Asked Questions


Discussion Summary

Synthetic benzodiazepines are increasingly common as counterfeit (pressed) benzodiazepine tablets.

False-positive benzodiazepine screens can occur from some cross-reacting drugs, sertraline (for clonazepam in particular), efavirenz, and a few other available drugs but this varies by particular immunoassay or other preliminary tests.

Some synthetic/designer benzodiazepines will trigger a preliminary assay positive, but metabolites are not the same as the tested benzodiazepine metabolites so confirmation will be negative ( e.g flualprazolam triggers a preliminary benzodiazepine screen positive but is not confirmed as alprazolam)

Gabapentinoids are commonly misused by patients with opioid use disorders (as opioid potentiators). Gabapentin is most common, but also pregabalin and baclofen, and other non-benzodiazepines sedatives described above.


Full Case Discussion can be found here: 

  1. “Appropriate Use of Drug Testing in Clinical Addiction Medicine” American Society of Addiction Medicine, 5 Apr. 2017
  2. J.B. Zawilska and J. Wojcieszak, 2019. An expanding world of new psychoactive substances—designer benzodiazepine. Neurotoxicology 73 (2019) 8–16
  3. “Xanax bars.” Addiction Health,
  4. D.M. Papsun, A.J Krotulski, J. Homan, K.D.H Temporal and B.K. Logan, 2020. Flualprazolam Blood Concentrations in 197 Forensic Investigation Cases. J Anal Toxicol. 2020 Jun 12;bkaa070. doi: 10.1093/jat/bkaa070
  5. Wiegand TJ.  A 3 day Phenobarbital Protocol for Benzodiazepine Detoxification -Description of Use During Buprenorphine Initiation in a Detoxification Facility.  Journal of Medical Toxicology (2019); 15:53-107.  Abstract 20: Page 59. 
  6. Hood SD, Normal A, Hince DA, Melichar JK and Hulse GK.  Benzodiazepine dependence and its treatment with low dose flumazenil.  British Journal of Clinical Pharmacology.  2014 Feb; 77(2): 285-294.  PMID: 23126253.
  7. C.W. Goodman, and A.S. Brett, 2019. Gabapentinoids for Pain: Potential Unintended Consequences. Am Fam Physician. 2019 Dec 1 :100(11):672-675.
  8. (Mentioned in the webinar video) Orsalini ‘New/Designer Benzodiazepines’: an analysis of the literature and psychonauts’ trip reports