False methadone-positive urine drug screens in patients treated with quetiapine

Urine drug screens: Considerations for the psychiatric pharmacist

Introduction:

Proper psychiatric evaluation of patients necessitates that the clinician be vigilant in ruling out secondary causes of symptoms, such as substance-induced symptoms. Immunoassay-type urine drug screens (UDSs) offer clinicians rapid drug screen results, ease of use, and inexpensive cost. Unfortunately, these screens are not without their limitations. This review aims to outline the nuances and limitations of immunoassay UDSs and to provide the clinician with information that facilitates more accurate interpretation of UDS results. Specifically, false positive results associated with psychiatric medications and the availability and methods for acquisition of commercialized UDS masking agents will be reviewed.

Methods:

A literature review was conducted to identify false positive UDSs associated with psychiatric medications. References for each article identified were also reviewed. Additionally, a Google® search was conducted to identify commercially available preparations used to mask UDS results and the methods of acquisition of these products.

Results:

A total of 14 articles were identified using PubMed. No articles for mood stabilizing agents were identified. Entering the phrase how to pass a drug test into Google® search yielded about 12.6 million results, and select references were reviewed based on relevance and user reviews.

Discussion:

Several psychiatric medications are documented as potential sources of false positive UDSs. Additionally, several agents are available for consumer purchase that may result in false negative UDSs. The clinician must be vigilant in interpreting immunoassay UDS results and should utilize more advanced forms of testing as clinically appropriate.

False-positive interferences of common urine drug screen immunoassays: a review

Urine drug screen (UDS) immunoassays are a quick and inexpensive method for determining the presence of drugs of abuse. Many cross-reactivities exist with other analytes, potentially causing a false-positive result in an initial drug screen. Knowledge of these potential interferents is important in determining a course of action for patient care. We present an inclusive review of analytes causing false-positive interferences with drugs-of-abuse UDS immunoassays, which covers the literature from the year 2000 to present. English language articles were searched via the SciFinder platform with the strings 'false positive [drug] urine' yielding 173 articles. These articles were then carefully analyzed and condensed to 62 that included data on causes of false-positive results. The discussion is separated into six sections by drug class with a corresponding table of cross-reacting compounds for quick reference. False-positive results were described for amphetamines, opiates, benzodiazepines, cannabinoids, tricyclic antidepressants, phencyclidine, lysergic acid diethylamide and barbiturates. These false-positive results support the generally accepted practice that immunoassay positive results are considered presumptive until confirmed by a second independent chemical technique.

Accuracy of self-report, biological tests, collateral reports and clinician ratings in identifying substance use disorders among adults with schizophrenia

Identifying substance use disorders among adults with schizophrenia presents unique challenges but is critical to research and practice. This study examined: (a) the accuracy of assessments completed using various approaches in identifying substance use disorders, (b) their ability to discriminate between disorders of abuse and dependence, and (c) the benefits of using multiple indicators to identify substance use disorders. Data are from the Clinical Antipsychotic Trials of Intervention Effectiveness study. The sample comprised 1,460 community-based adults with schizophrenia, 15.8% (n = 230) of whom were positive for a current (past month) drug or alcohol use disorder using the Structured Clinical Interview for DSM-IV Disorders (SCID). Clinician ratings, self-report, collateral reports, and results of hair and urine tests were compared to SCID diagnoses. Congruence with SCID diagnoses was good across approaches and evidence for superiority of one approach over another was limited. No approach discriminated between abuse and dependence. There was limited benefit of using multiple indicators. Findings suggest that the decision regarding the "best" approach for identifying substance use disorders among adults with schizophrenia may be made through consideration of practical issues and assessment purpose, rather than selection of the approach that yields the most accurate diagnostic assessment.

‘False-positive’ and ‘false-negative’ test results in clinical urine drug testing

The terms ‘false-positive’ and ‘false-negative’ are widely used in discussions of urine drug test (UDT) results. These terms are inadequate because they are used in different ways by physicians and laboratory professionals and they are too narrow to encompass the larger universe of potentially misleading, inappropriate and unexpected drug test results. This larger universe, while not solely comprised of technically ‘true’ or ‘false’ positive or negative test results, presents comparable interpretive challenges with corresponding clinical implications. In this review, we propose the terms ‘potentially inappropriate’ positive or negative test results in reference to UDT results that are ambiguous or unexpected and subject to misinterpretation. Causes of potentially inappropriate positive UDT results include in vivo metabolic conversions of a drug, exposure to nonillicit sources of a drug and laboratory error. Causes of potentially inappropriate negative UDT results include limited assay specificity, absence of drug in the urine, presence of drug in the urine, but below established assay cutoff, specimen manipulation and laboratory error. Clinical UDT interpretation is a complicated task requiring knowledge of recent prescription, over-the-counter and herbal drug administration, drug metabolism and analytical sensitivities and specificities.