Prescription Compliance or Illicit Designer Drug Abuse?

Solriamfetol and m-chlorophenylpiperazine cause false positive amphetamine results on urine drug screening

Urine drug screening by immunoassay is a common method to quickly identify drug exposures in the emergency setting and to detect unexpected drug exposures in a variety of patient care and occupational health settings. Although they provide rapid results, immunoassays are susceptible to cross-reactivity with other medications and metabolites. Herein we evaluate the performance of the Thermo Scientific DRI Amphetamines immunoassay for reactivity with trazodone, aripiprazole, atomoxetine, solriamfetol and relevant metabolites. Each of these compounds were spiked into drug-free urine across a range of concentrations and assessed for positivity on amphetamine screen. We demonstrate that the Thermo Scientific DRI assay is susceptible to interferences from m-chlorophenylpiperazine (mCPP), the main metabolite of trazodone, and solriamfetol. Characterization of assay-specific interferences in toxicology screening is instrumental for accurate interpretation of toxicology results, evaluation of patients in emergent settings and supporting patient care.

Investigation and Resolution of Interference in the LC-QTOF-MS Detection of 4-MePPP

An interference resulting in the false-positive detection of the synthetic cathinone 4-MePPP in urine was suspected following the recent addition of 4-MePPP spectral data to an LC-QTOF-MS drug library. Although positive detection criteria were achieved, it was noted that all urine samples suspected of containing 4-MePPP also concurrently contained high levels of tramadol and its associated metabolites. Using QTOF-MS software elucidation tools, candidate compounds for the suspected interference were proposed. To provide further confidence in the identity of the interference, in silico fragmentation tools were used to match product ions generated in the analysis with product ions predicted from the theoretical fragmentation of candidate compounds. The ability of the suspected interference to subsequently produce the required product ions for spectral library identification of 4-MePPP was also tested. This information was used to provide a high preliminary confidence in the compound identity prior to purchase and subsequent confirmation with certified reference material. A co-eluting isobaric interference was identified and confirmed as an in-source fragment of the tramadol metabolite, N,N-bisdesmethyltramadol. Proposed resolutions for this interference are also described and subsequently validated by retrospective interrogation of previous cases of suspected interference.

The Impact of Mass Spectrometry on Patients' Medical and Nonmedical Lives

OBJECTIVE

The various forms of mass spectrometry (MS) instrumentation have had a major impact on testing for analytes performed with clinical and forensic laboratories over the past decade. Improvements in MS instrumentation have led to the use of MS in many areas.

METHODS

To highlight the value of MS testing, short reports are presented that are relevant to the following fields: pain management, transplant medicine, clinical toxicology, designer drug testing, genetic metabolic disorders, nutrition, dietary exposure to heavy metals, herbals and supplements, forensic pathology, pharmacogenomics, homeland security, performance enhancing drugs and peptides, clinical microbiology, physician licensing, and environmental exposures. These reports are based on real patients. The "stories" have been altered to comply with privacy regulations.

RESULTS

Analysis of MS provides objective results that have an impact on many areas of medicine and society as a whole. Accurate analysis has an impact on guidance for medical practices.

CONCLUSION

The value of MS testing will continue to grow in the years to come.

Accidental intoxications in toddlers: lack of cross-reactivity of vilazodone and its urinary metabolite M17 with drug of abuse screening immunoassays

Background

Vilazodone is an FDA approved medication used to treat major depressive disorder. The authors describe two cases of accidental vilazodone exposure in toddlers who presented with symptoms similar to amphetamine exposure and also with unexplained positive amphetamine urine immunoassay drug screens. Given a lack of published data on cross-reactivity of vilazodone and its metabolites with drug of abuse screening tests, the authors investigated drug of abuse immunoassay cross-reactivity of vilazodone and metabolites using computational and empirical approaches.

Methods

To ascertain the likelihood that vilazodone would cross-react with drug of abuse screening immunoassays, the authors assessed the two-dimensional (2D) similarity of the vilazodone parent molecule and known metabolites to an array of antigenic targets for urine immunoassay drug screens. To facilitate studies of the commercially unavailable M17 metabolite, it was prepared synthetically through a novel scheme. Urine and serum were spiked with vilazodone and M17 into urine (200–100,000 ng/mL) and serum (20–2000 ng/mL) samples and tested for cross-reactivity.

Results

Computational analysis using 2D similarity showed that vilazodone and metabolites have generally low similarity to antigenic targets of common drug of abuse screening immunoassays, predicting weak or no cross-reactivity. The M17 metabolite had 2D similarity to amphetamines and tricyclic antidepressants in a range similar to some other compounds exhibiting weak cross-reactivity on these immunoassays. Cross-reactivity testing was therefore performed on two different urine amphetamines immunoassays and a serum tricyclic antidepressant immunoassay. However, actual testing of cross reactivity for vilazodone and the M17 metabolite did not detect cross-reactivity for any urine amphetamines screen at concentrations up to 100,000 ng/mL and for a serum tricyclic antidepressants assays at concentrations up to 2000 ng/mL.

Conclusion

While the vilazodone metabolite M17 has weak 2D structural similarity to amphetamines and tricyclic antidepressants, the current study did not demonstrate any experimental cross-reactivity with two different urine amphetamines immunoassays and a serum tricyclic antidepressant immunoassay. Vilazodone ingestions in young children present a diagnostic challenge in their similarity to amphetamine ingestions and the lack of routine laboratory tests for vilazodone. Further work is needed to understand the metabolic profile for vilazodone in children versus adults.

Electronic supplementary material

The online version of this article (10.1186/s12907-019-0084-9) contains supplementary material, which is available to authorized users.

High-Resolution Mass Spectrometry for Untargeted Drug Screening

While gas chromatography-mass spectrometry (GC/MS) continues to be the forensic standard for toxicology, liquid chromatography coupled to tandem MS offers significant operational advantages for targeted confirmatory analysis. LC-high-resolution (HR)-MS has recently been available that offers advantages for untargeted analysis. HR-MS analyzers include the Orbitrap and time-of-flight MS. These instruments are capable of detecting 1 ppm mass resolution. Following soft ionization, this enables the assignment of exact molecular formula, limiting the number of candidate compounds. With this technique, presumptive identification of unknowns can be conducted without the need to match MS library spectra or comparison against known standards. For clinical toxicology, this can greatly expand on the number of drugs and metabolites that can be detected and reported on a presumptive basis. Definitive assignments of the compound's identity can be retrospectively determined with acquisition of the appropriate reference standard.