Expires: December 2, 2022
Paul Jannetto, Ph.D., is the Director of the Clinical and Forensic Toxicology Lab and Clinical Mass Spectrometry Lab in the Department of Laboratory Medicine and Pathology in Rochester, Minnesota. He holds the academic rank of Associate Professor.
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Hi, I’m Bobbi Pritt, Director of the Clinical Parasitology Lab and Vice Chair of Education in the Department of Laboratory Medicine and Pathology at Mayo Clinic. Did you know that compliance monitoring of benzodiazepines are recommended by numerous clinical practice guidelines using drug tests because of their high risk of misuse, abuse, and diversion? In this month’s “Hot Topic,” my colleague, Dr. Paul Jannetto, will highlight Mayo Clinic’s new targeted benzodiazepine assay and discuss the advantages and limitations of various urine screening assays and quantitative confirmatory testing to determine compliance to benzodiazepine therapy. I hope you enjoy this month’s Hot Topic, and I want to personally thank you for allowing Mayo Clinic the opportunity to be a partner in your patient’s health care.
Thank you for that introduction.
I have nothing to disclose.
The objectives of my talk are to:
Benzodiazepines are a large class of central nervous system (CNS) depressant medications with useful sedative, hypnotic, anxiolytic, and anticonvulsant properties.
There are short, intermediate, and long-acting benzodiazepines, which are commonly prescribed for:
Benzodiazepines work by raising the levels of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the brain.
Some commonly prescribed benzodiazepines include: diazepam, alprazolam, clonazepam, and lorazepam.
Benzodiazepines are listed by the U.S. Drug Enforcement Administration (DEA) as schedule IV controlled substances, which means they have the potential for abuse, addiction, and diversion. As a result, urine drug tests are recommended by numerous clinical practice guidelines to monitor compliance/adherence to these medications.
Unfortunately, with the opioid epidemic in America, benzodiazepines are also found in greater than 30% of opioid overdoses, which further drives the need to perform urine drug testing for these medications.
So what types of urine tests are being used by physicians to determine compliance to benzodiazepines? Physicians may use screening assays or definitive assays. However, physicians are primarily using screening assays with or without confirmatory tests to verify adherence of benzodiazepines.
There are two types of screening assays. One type includes traditional screening assays that use antibodies directed against a drug or drug metabolite. These immunoassays may be in a point-of-care format so the test can be done right in the physician’s office or clinic, or they can be commercially based immunoassays run in CLIA-certified laboratories. Alternatively, new targeted laboratory-developed screening assays using mass spectrometry have also started to emerge as a screening tool, like the new benzodiazepine assay I am talking to you about today. Each of these types of assays has advantages and disadvantages.
Point-of-care tests have the advantage of having the fastest turnaround time, so the physicians can receive an immediate result, which is good for patients who have a high risk for abuse or reside far from care. Laboratory-based immunoassays typically are more economical. However, all immunoassays suffer from higher cutoffs, limited sensitivity, and specificity. On the other hand, targeted screens have better sensitivity and specificity, but they aren’t widely available at all local laboratories.
Cross-reactivity with immunoassays is a big issue that needs to be considered when interpreting screening results:
Now, let’s look at one clinical case study which uses a traditional immunoassay approach with reflexing to confirmatory testing when positive.
In this case, we have a 55-year-old female with an anxiety disorder who is being prescribed lorazepam (a benzodiazepine). The patient’s anxiety is well-controlled, but per institutional guidelines, the physician wants to order a urine drug test that uses several different immunoassays to screen for the prescribed benzodiazepine as well as commonly abused drugs.
The purpose of the urine drug tests is to check for adherence to the prescribed medication and make sure the patient isn’t abusing other medications. However, you can see the immunoassay screening results all came back “negative,” including the benzodiazepine immunoassay.
As a result, how should the physician interpret these results? Is the patient compliant?
This slide shows a simplified metabolic pathway for benzodiazepines. Each blue box contains a separate prescribable benzodiazepine (e.g., parent drug). The arrows then indicate the metabolites formed in the body when the drug is broken down.
In this case, the physician then called the laboratory back to add on a confirmatory benzodiazepine test that uses liquid chromatography tandem mass spectrometry to specifically look for lorazepam. The confirmatory test also uses a hydrolysis reaction to cleave off the glucuronides to enable better detection of the parent form of the drug, if present. In this case, the results show lorazepam was present at a concentration of 8,250 ng/mL, which also explains why the immunoassay was “negative” since the concentration of lorazepam glucuronide would have had to have been greater than 19,615 ng/mL to trip this immunoasay “positive”.
Now, let’s look at Mayo Clinic’s new high-resolution targeted benzodiazepine screen (or TABSU).
The use of mass spectrometry-based technologies to screen for benzodiazepines is consistent with the evidence-based laboratory medicine practice guideline entitled, “Using Clinical Laboratory Tests to Monitor Drug Therapy in Pain-Management Patients,” that was published in January 2018 in the Journal of Applied Laboratory Medicine.
One of the recommendations was that qualitative definitive tests should be used instead of immunoassays, since they are more effective at identifying prescribed medications and illicit substances in pain-management patients.
The features and benefits of the new high-resolution targeted benzodiazepine screen, TABSU, include:
On this slide is the complete list of the 27 benzodiazepines and metabolites along with the cutoffs or concentration required to give a positive or “present” result. This one test will enable clinicians so that they don’t have to remember which benzodiazepine does or does not cross-react with the urine benzodiazepine immunoassay or have to order additional costly confirmation tests to look for all of the different benzodiazepines.
On this slide is an example of an enhanced report. If anything was positive, those results would have been pulled up into the top section of the report so the clinician can immediately see what was present or detected. It also provides some additional information regarding brand names or if something is a metabolite of another drug.
In addition to being a separate orderable test, the high-resolution targeted benzodiazepine screen (TABSU) will also be available as part of the new controlled substance monitoring panel (CSMP).
This slide shows the algorithm for the CSMP where adulteration or specimen validity testing is performed first. If the sample is adulterated, testing stops and no charge is issued to the client/patient. If the sample is not adulterated, testing then resumes with the targeted screens for opioids and benzodiazepines along with the traditional immunoassays.
In summary, objective measures like laboratory tests are needed to identify and evaluate adherence or misuse or abuse of controlled substances.
The new high-resolution targeted benzodiazepine assay can:
In the end, all urine drug test results must be interpreted in the context of the test, drugs prescribed, specimen type, time since last dose and sample collection, specimen validity test results, and the patient. Unexpected or unexplained results should be discussed with the patient and laboratory, and additional testing should be performed if needed.
Thank you for your attention. I hope you found this presentation useful. If you have any questions, please contact Mayo Clinic Laboratories.