Unresolved Discrepancies between Cannabinoid Test Results for Infant Urine

High-sensitivity neonatal urine drug testing has similar positivity rates to meconium for detecting in utero exposure to methamphetamine and cocaine

Current guidelines recommend universal screening for substance use disorders in obstetric patients, and neonatal drug testing is also frequently performed. Meconium is often the preferred specimen type to detect neonatal drug exposure due to a longer window of detection compared to urine, but most laboratories send out meconium testing to specialized reference laboratories, which can delay results for several days or more. Here, we evaluate a rapid and definitive liquid chromatography-tandem mass spectrometry method for neonatal urine drug testing and compare results obtained using this method to paired meconium drug testing in 1,424 neonates for amphetamines, cocaine, cannabinoids, opiates, oxycodone and phencyclidine. Urine testing showed equivalent sensitivity to current meconium methods for detecting in utero exposure to amphetamines and cocaine.

Drug testing in support of the diagnosis of neonatal abstinence syndrome: The current situation

Illicit drug use during pregnancy is a concern worldwide, with many international studies describing attempted strategies to mitigate this problem. Drug misuse during pregnancy is associated with significant maternal as well as perinatal complications, which include a high incidence of stillbirths, fetal distress, neonatal abstinence syndrome (NAS) and increased neonatal mortality. Unfortunately, the identification of a drug-exposed mother or neonate is challenging. Maternal disclosure of drug use is often inaccurate, principally due to psychosocial factors including behavioral denial or the fear of the consequences resulting from such admissions. Likewise, many infants who have been exposed to drugs in utero may appear normal at birth and initially show no overt manifestations of drug effects. Thus, the identification of the drug-exposed infant requires a high index of clinical suspicion. Conversely, analytical testing is an objective means of determining drug exposure when it may be necessary to document proof of the infant's exposure to illicit drugs. The review will discuss the different matrices that are most commonly used for testing (e.g., maternal urine, neonatal urine, meconium, and umbilical cord), the strengths and limitations for each matrix, which drugs and metabolites are appropriate for testing, the various testing methods, and the advantages and disadvantages of each method.

Development and Implementation of One-Step, Broad-Spectrum, High-Sensitivity Drug Screening by Tandem Mass Spectrometry in a Pediatric Population

Background

Drug screening by immunoassay is common in pediatric populations. However, false-positive and -negative results due to antibody cross-reactivity and dilute urine are frequent and underappreciated. Accurate ascertainment of drug exposure in children has significant clinical and medico-legal consequences.

Design and Methods

We developed and characterized an LC–MS/MS drug screening assay to supplant immunoassay and detect 38 compounds at the lowest concentrations distinguishable from analytic noise. Once implemented, we conducted a retrospective analysis of 3985 pediatric urine drug screens performed a year before (n = 1663) and after (n = 2322) implementation to examine the frequency and breadth of drug detection in our pediatric population.

Results

Using immunoassay, 23% (293/1269) of samples from the general pediatric and 37% (147/394) of nursery populations had presumptively positive results. Of the presumptive positive compounds, 85% (288/338) from the general pediatric population and 40% (65/162) from the nursery cohort were confirmed by mass spectrometry. After LC–MS/MS implementation, 31% (628/2052) of general pediatric, and 18% (48/270) of the nursery samples were positive for 1 or more compounds. In the nursery population, immunoassays over-detected the presence of THC but under-detected exposure to cocaine.

Conclusion

A broadly targeted, analytically sensitive LC–MS/MS drug screening assay detects a larger number and variety of compounds in a single step compared to a screen-then-confirm approach initiated by immunoassay in our pediatric population. Rapid delivery of accurate results enables timely, appropriate disposition of patients in a variety of settings including the emergency department and labor/delivery.

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.

13-year-old girl with recurrent, episodic, persistent vomiting: out of the pot and into the fire

Cyclic vomiting syndrome (CVS) is a well-established cause of recurrent vomiting in the pediatric population. Severe vomiting with chronic cannabis use, known as cannabinoid hyperemesis syndrome, has recently been more widely recognized as an etiology of persistent episodic vomiting. In turn, patients presenting with frequent episodes of CVS are now increasingly being screened for cannabinoid use. Because patients with persistent vomiting are also frequently prescribed a proton pump inhibitor (PPI) for their gastrointestinal symptoms, it is important to be aware of the potential for a PPI to cause an interaction that can lead to false-positive urine cannabinoid screening. We describe a case of a false-positive urine cannabinoid screen in a patient with CVS who received a dose of intravenous pantoprazole. The primary reference regarding drug screen interference from PPIs can be found in the pantoprazole package insert that refers to pre-Food and Drug Administration approval data. Although multiple sources on the Internet report the possibility of positive cannabinoid screens from pantoprazole, there are no known published reports of the phenomenon in the medical literature.

Retrospective analysis of the diagnostic yield of newborn drug testing

Background

The objective of this study was to identify high-yield screening risk factors for detecting maternal non-medical drug use during pregnancy.

Methods

A four year retrospective analysis was conducted at an academic medical center. Detailed chart review of both the newborn and mother’s medical record was performed on all cases for which one or more drug(s) or metabolite(s) were identified and confirmed in meconium or urine.

Results

229 (9.2%) of 2,497 meconium samples out of 7,749 live births confirmed positive for one or more non-medical drugs. History of maternal non-medical drug and/or tobacco use in pregnancy was present in 90.8% of non-medical drug use cases. Addition of social risk factors and inadequate prenatal care increased the yield to 96.9%.

Conclusions

Use of focused screening criteria based on specific maternal and social risk factors may detect many prenatal non-medical drug exposures.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2393-14-250) contains supplementary material, which is available to authorized users.