Urinary Buprenorphine, Norbuprenorphine and Naloxone Concentrations and Ratios: Review and Potential Clinical Implications

Clinical implications of opioid parent-metabolite ratios

BACKGROUND

The opioid epidemic has underscored the importance of urine drug testing in the management of chronic pain. However, interpreting test results can be challenging, especially in scenarios where medications may have been directly added to urine samples to simulate compliance.

METHODS

We conducted a retrospective analysis of 9,690 opioid testing results using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The study aimed to define the expected ratios between parent drugs and metabolites for eight commonly prescribed opioids. Cases with a parent-metabolite ratio above the 95th percentile were subjected to chart review.

RESULTS

A total of 13 cases appeared likely consistent with simulated compliance with buprenorphine, 2 with methadone, 14 with oxycodone, and one with hydrocodone. The unusual patterns of parent-metabolite ratio can also be associated with hyperacute drug exposures/use, pharmaceutical impurity, or underlying liver enzyme deficiency. Furthermore, patients who failed the decision limits could exhibit other illicit use or aberrant behaviors.

CONCLUSION

Laboratories conducting LC-MS/MS-based opioid testing can more objectively identify anomalies by analyzing parent-metabolite ratios. When in consultation with providers, laboratories can point to these data when suggesting the possibility of simulated compliance and help identify cases warranting further investigation.

Buprenorphine/naloxone - one formulation that doesn't fit all: a case report

BACKGROUND

Sublingual buprenorphine, approved for treatment of opioid use disorder since 2002, is most commonly available in co-formulation with naloxone. Naloxone is an opioid antagonist minimally absorbed when sublingual (SL) buprenorphine/naloxone is taken as prescribed; it is thought to reduce potential for misuse via intravenous administration. However, growing data and clinical experience demonstrate that previously accepted assumptions about the pharmacokinetics of these medications may not apply to all patients.

CASE PRESENTATION

We present a patient whose adverse post-administration side effects on SL buprenorphine/naloxone resolved with transition to SL buprenorphine monoproduct.

DISCUSSION

Naloxone can be detected in nearly all patients taking SL buprenorphine/naloxone, though with apparent variability in clinical effect. In a minority of patients, naloxone can contribute to adverse and potentially treatment-limiting side effects. Furthermore, the naloxone component is commonly misunderstood by patients and providers and can foster mistrust in the therapeutic relationship if providers are perceived to be withholding a more tolerable formulation. Prescribers should have a low threshold to offer buprenorphine alone when clinically appropriate.

Assessing knowledge gaps and educational needs in urine drug test interpretation among health care professionals

OBJECTIVES

Urine drug testing (UDT) is a critical tool used in medical, forensic, and occupational settings, but interpreting results can be challenging. We performed a study to assess the ability of health care professionals to interpret UDT results accurately.

METHODS

In total, 911 clinical and laboratory professionals in the United States and Canada responded to a survey with questions gauging expertise in UDT interpretation. Responses were analyzed to identify knowledge gaps.

RESULTS

Toxicologists and laboratory PhD scientists performed well, with means of 4.82 and 4.63 questions answered correctly (out of 6 possible), respectively. Physicians specializing in pathology, emergency medicine, primary care, and internal medicine, however, displayed concerning knowledge gaps, as did laboratorians with nondoctoral degrees. Experience and training correlated with interpretation accuracy. Identification of simulated compliance as well as understanding opioid exposure, metabolism, and immunoassay cross-reactivity were among the most clinically significant knowledge gaps. More than 30% of survey respondents indicated that they would seek UDT information from the internet or peers rather than clinical or laboratory experts.

CONCLUSIONS

The study highlighted the need for targeted education and better collaboration between clinical and laboratory experts and other health care professionals to ensure that when physicians order UDT, they can accurately interpret results and reduce harm.

Monitoring buprenorphine in patients on medication-assisted treatment

BACKGROUND

Buprenorphine is used for medication-assisted treatment of opioid dependence.

PURPOSE

Monitoring of medication adherence involves testing of urine or oral fluid for the drug or its metabolite.

METHODS

Quantitative results using liquid chromatography tandem mass spectrometer testing defined the excretion pattern of the drug and its metabolites.

RESULTS

Frequency distribution curves of buprenorphine and norbuprenorphine describe the expected drug concentrations of patients on this medication.

CONCLUSION

Urine and oral fluid drug testing can be used to monitor adherence in this population.

Buprenorphine, Norbuprenorphine, and Naloxone Levels in Adulterated Urine Samples: Can They be Detected When Buprenorphine/Naloxone Film is Dipped into Urine or Water?

Reportedly, various urine manipulations can be performed by opioid use disorder (OUD) patients who are on buprenorphine/naloxone medications to disguise their non-compliance to the treatment. One type of manipulation is known as "spiking" adulteration, directly dipping a buprenorphine/naloxone film into urine. Identifying this type of urine manipulation has been the aim of many previous studies. These studies have revealed urine adulterations through inappropriately high levels of "buprenorphine" and "naloxone" and a very small amount of "norbuprenorphine." So, does the small amount of "norbuprenorphine" in the adulterated urine samples result from dipped buprenorphine/naloxone film, or is it a residual metabolite of buprenorphine in the patient's system? This pilot study utilized 12 urine samples from 12 participants, as well as water samples as a control. The samples were subdivided by the dipping area and time, as well as the temperature and concentration of urine samples, and each sublingual generic buprenorphine/naloxone film was dipped directly into the samples. Then, the levels of "buprenorphine," "norbuprenorphine," "naloxone," "buprenorphine-glucuronide" and "norbuprenorphine-glucuronide" were examined by Liquid Chromatography with tandem mass spectrometry (LC-MS/MS). The results of this study showed that high levels of "buprenorphine" and "naloxone" and a small amount of "norbuprenorphine" were detected in both urine and water samples when the buprenorphine/naloxone film was dipped directly into these samples. However, no "buprenorphine-glucuronide" or "norbuprenorphine-glucuronide" were detected in any of the samples. In addition, the area and timing of dipping altered "buprenorphine" and "naloxone" levels, but concentration and temperature did not. This study's findings could help providers interpret their patients' urine drug test results more accurately, which then allows them to monitor patient compliance and help them identify manipulation by examining patient urine test results.

Investigation of Simulated Adherence in Long-Term Buprenorphine/Naloxone Treatment Patients

BACKGROUND

Buprenorphine is a medication that is used to treat opioid use disorder by reducing withdrawal symptoms and cravings for opioids. Patients with poor adherence are at higher risk of relapse and overdose. Providers often test adherence through urine testing but are not aware of simulated adherence, where patients may directly add buprenorphine to the urine samples. As of now, there exists no literature on the simulated adherence practices for patients who stayed in the treatment for more than three months.

METHODS

This study is a cross-sectional analysis of simulated adherence through urine toxicology results of 3950 patients undergoing buprenorphine/naloxone treatment. Simulated adherence was measured by the ratio of norbuprenorphine and buprenorphine <0.02 in the urine sample. Descriptive statistics as well as multivariate analysis was conducted to examine the relationship between patient information and outcomes.

RESULTS

Out of 3950 patients, 411 (10.4%) had a history of one or more simulated adherence. On average, patients with multiple simulated adherences had 48.1% of their tests simulated, while on the contrary, patients with a single occurrence of simulated adherence had 17.6% of their tests simulated. Weekly testing and visit number of over 15 were associated with a higher likelihood of simulated adherence.

CONCLUSION

The study demonstrates that simulated adherence is a recurring phenomenon among buprenorphine/naloxone treatment patients regardless of the duration in the treatment. Utilization of quantitative urine toxicology to identify simulated adherence will enable healthcare providers to formulate a more precise and effective treatment plan tailored to support individual patient needs.

Evaluation of adherence monitoring in buprenorphine treatment: A pilot study using timed drug assays to determine accuracy of testing

AIMS

Buprenorphine is effective at reducing relapse to opioid misuse, morbidity and mortality in opioid-dependent patients. Urine drug screening (UDS) to assess adherence is used routinely in opioid agonist treatment (OAT). The primary aim of this study was to determine factors which may be associated with a negative qualitative urine drug screen for buprenorphine in OAT patients.

METHODS

This prospective pilot study was conducted at a tertiary addiction medicine centre. Twenty participants on stable treatment underwent supervised administration of sublingual buprenorphine. Matched urine and blood samples were collected prior to and 2, 4 and 6 hours after buprenorphine administration. Qualitative urine drug screen results were obtained using gas chromatography-mass spectrometry (GC-MS), while quantitative blood and urine results were obtained using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

RESULTS

Qualitative urine assay yielded a negative result for buprenorphine in 57% of tested samples. The median concentration of urinary buprenorphine was 167 mcg/L (range: 2-1730 mcg/L). Thirty percent of all blood samples did not detect buprenorphine (range 0-18 mcg/L). Positive qualitative urine drug screen results were associated with higher urine (343 mcg/L compared with 75 mcg/L; P < .05) and blood (4 mcg/L compared with 2 mcg/L; P < .05) buprenorphine concentrations. Median urine concentrations of buprenorphine were highest at 2 hours and were higher in participants receiving CYP3A4 inhibitors.

CONCLUSION

Interpretation of qualitative urine drug screens to assess adherence in OAT is complex. Poor adherence with treatment cannot be assumed in patients returning a negative qualitative GC-MS urine drug screen.

Association of Patients' Direct Addition of Buprenorphine to Urine Drug Test Specimens With Clinical Factors in Opioid Use Disorder

Importance

The direct addition of buprenorphine to urine drug test specimens to mimic results suggestive of adherence is a clinically significant result, yet little is known about the phenomenon.

Objective

To characterize factors associated with the direct addition of buprenorphine to urine specimens among patients prescribed buprenorphine for opioid use disorder.

Design, Setting, and Participants

This cross-sectional study of urine drug test specimens was conducted from January 1, 2017, to April 30, 2022, using a national database of urine drug test specimens ordered by clinicians from primary care, behavioral health, and substance use disorder treatment clinics. Urine specimens with quantitative norbuprenorphine and buprenorphine concentrations from patients with opioid use disorder currently prescribed buprenorphine were analyzed.

Exposures

Nonprescribed opioid or stimulant co-positive, clinical setting, collection year, census division, patient age, patient sex, and payor.

Main Outcomes and Measures

Norbuprenorphine to buprenorphine ratio less than 0.02 identified direct addition of buprenorphine. Unadjusted trends in co-positivity for stimulants and opioids were compared between specimens consistent with the direct addition of buprenorphine. Factors associated with the direct addition of buprenorphine were examined with generalized estimating equations.

Results

This study included 507 735 urine specimens from 58 476 patients. Of all specimens, 261 210 (51.4%) were obtained from male individuals, and 137 254 (37.7%) were from patients aged 25 to 34 years. Overall, 9546 (1.9%) specimens from 4550 (7.6%) patients were suggestive of the direct addition of buprenorphine. The annual prevalence decreased from 2.4% in 2017 to 1.2% in 2020. Opioid-positive with (adjusted odds ratio [aOR], 2.01; 95% CI, 1.85-2.18) and without (aOR, 2.02; 95% CI, 1.81-2.26) stimulant-positive specimens were associated with the direct addition of buprenorphine to specimens, while opioid-negative/stimulant-positive specimens were negatively associated (aOR, 0.78; 95% CI, 0.71-0.85). Specimens from patients aged 35 to 44 years (aOR, 1.59; 95% CI, 1.34-1.90) and primary care (aOR, 1.60; 95% CI, 1.44-1.79) were associated with the direct addition of buprenorphine. Differences by treatment setting decreased over time. Specimens from the South Atlantic census region had the highest association (aOR, 1.4; 95% CI, 1.25-1.56) and New England had the lowest association (aOR, 0.54; 95% CI, 0.46-0.65) with the direct addition of buprenorphine.

Conclusions and Relevance

In this cross-sectional study, the direct addition of buprenorphine to urine specimens was associated with other opioid positivity and being collected in primary care settings. The direct addition of buprenorphine to urine specimens is a clinically significant finding, and best practices specific for this phenomenon are needed.

Bridging the gap: The critical role of laboratory developed tests in clinical toxicology

•Toxicology testing provides valuable information for patient management.•Current in vitro diagnostics (IVDs) are unable to meet all clinical needs.•Lab-developed tests (LDTs) in toxicology can be used to close clinical care gaps.•LDTs in clinical toxicology are almost exclusively mass spectrometry-based methods.

Do buprenorphine doses and ratios matter in medication assisted treatment adherence?

Introduction

Buprenorphine (BUP), generally prescribed as buprenorphine/naloxone, is a key component of medication-assisted treatment (MAT) to manage opioid use disorder. Studies suggest higher doses of BUP increase treatment adherence. Routine urine drug screens (UDS) assist in monitoring MAT adherence via measurement of excreted BUP and its metabolite, norbuprenorphine (NBP). The clinical significance between BUP/NBP concentrations and their ratios for assessing adherence and substance use is not well-described.

Methods

We conducted a single-center, retrospective chart review of 195 clients age ≥18 years enrolled in a local MAT program from August 2017 to February 2021. Demographics, BUP doses, prescription history, and UDS results were collected. Participants were divided based on MAT adherence (<80% vs ≥80%) and median total daily dose (TDD) of BUP (≥16 mg vs <16 mg) in addition to pre- and post-COVID-19 cohorts.

Results

Median BUP/NBP urinary concentrations were significantly correlated with MAT adherence (P < .0001 for each) and a reduced percentage of positive UDS for opioids (P = .0004 and P < .0001, respectively) but not their ratios. Median TDD of BUP ≥16 mg (n = 126) vs <16 mg (n = 68) was not correlated with MAT adherence (P = .107) or incidence of nonprescription use (P = .117). A significantly higher incidence of UDS positive for opiates (P = .049) and alcohol (P = .035) was observed post-COVID-19.

Discussion

Clients appearing adherent to MAT who had higher concentrations of urinary BUP/NBP demonstrated a reduced incidence of opioid-positive UDS independent of the BUP dose prescribed. An increase in opioid- and alcohol-positive UDSs were observed during the COVID-19 pandemic.

The North American opioid epidemic: opportunities and challenges for clinical laboratories

Since 1999, the opioid epidemic in North America has resulted in over 1 million deaths, and it continues to escalate despite numerous efforts in various arenas to combat the upward trend. Clinical laboratories provide drug testing to support practices such as emergency medicine, substance use disorder treatment, and pain management; increasingly, these laboratories are collaborating in novel partnerships including drug-checking services (DCS) and multidisciplinary treatment teams. This review examines drug testing related to management of licit and illicit opioid use, new technologies and test strategies employed by clinical laboratories, barriers hindering laboratory response to the opioid epidemic, and areas for improvement and standardization within drug testing. Literature search terms included combinations of "opioid," "opiate," "fentanyl," "laboratory," "epidemic," "crisis," "mass spectrometry," "immunoassay," "drug screen," "drug test," "guidelines," plus review of PubMed "similar articles" and references within publications. While immunoassay (IA) and point-of-care (POC) test options for synthetic opioids are increasingly available, mass spectrometry (MS) platforms offer the greatest flexibility and sensitivity for detecting novel, potent opioids. Previously reserved as a second-tier application in most drug test algorithms, MS assays are gaining a larger role in initial screening for specific patients and DCS. However, there are substantial differences among laboratories in terms of updating test menus, algorithms, and technologies to meet changing clinical needs. While some clinical laboratories lack the resources and expertise to implement MS, many are also slow to adopt available IA and POC tests for newer opioids such as fentanyl. MS-based testing also presents challenges, including gaps in available guidance for assay validation and ongoing performance assessment that contribute to a dramatic lack of standardization among laboratories. We identify opportunities for improvement in laboratory operations, reporting, and interpretation of drug test results, including laboratorian and provider education and laboratory-focused guidelines. We also highlight the need for collaboration with providers, assay and instrument manufacturers, and national organizations to increase the effectiveness of clinical laboratory and provider efforts in preventing morbidity and mortality associated with opioid use and misuse.

A Descriptive analysis of urine drug screen results in patients with opioid use disorder managed in a primary care setting

BACKGROUND

Urine drug screening (UDS) is commonly used as part of treatment for opioid use disorder (OUD), including treatment with buprenorphine-naloxone for OUD in a primary care setting. Very little is known about the value of UDS, the optimum screening frequency in general, or its specific use for buprenorphine treatment in primary care. To address this question, we thought that in a stable population receiving buprenorphine-naloxone in the primary care setting it would be useful to know how often UDS yielded expected and unexpected results.

METHODS

We present a descriptive analysis of UDS results in patients treated with buprenorphine-naloxone for OUD in a primary care setting over a two-year period. An unexpected test result is: 1. A negative test for buprenorphine and/or 2. A positive test for opioids, methadone, cocaine and/or heroin.

RESULTS

A total of 161 patients received care during the study period and a total of 2588 test results were analyzed from this population. We found that 64.4% of the patient population (n = 104 patients) demonstrated both treatment adherence (as measured by buprenorphine positive test results) and no apparent unexpected test findings, as defined by negative tests for opioids, methadone, cocaine and heroin. Of the 161 patients, 20 results were positive for opioids, 5 for methadone, 39 for heroin and 2 for cocaine. Analysis at the UDS level demonstrated that, of the 2588 test results, 38 (1.5%) results did not have buprenorphine. Of the 2588, 28 (1.1%) test results were positive for opioids, 8 (0.3%) were positive for methadone, 39 (1.5%) for cocaine and 2 (0.1%) for heroin.

CONCLUSION

Given that the majority of patients in our study had expected urine results, it may be reasonable for less frequent urine testing in certain patients.

Determination of buprenorphine, norbuprenorphine, naloxone, and their glucuronides in urine by liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of buprenorphine (BUP), norbuprenorphine (NBUP), naloxone (NAL), and their glucuronide conjugates BUP-G, NBUP-G, and NAL-G in urine samples was developed. The method, omitting a hydrolysis step, involved non-polar solid-phase extraction, liquid chromatography on a C18 column, electrospray positive ionization, and mass analysis by multiple reaction monitoring. Quantification was based on the corresponding deuterium-labelled internal standards for each of the six analytes. The limit of quantification was 0.5 μg/L for BUP and NAL, 1 μg/L for NAL-G, and 3 μg/L for NBUP, BUP-G, and NBUP-G. Using the developed method, 72 urine samples from buprenorphine-dependent patients were analysed to cover the concentration ranges encountered in a clinical setting. The median (maximum) concentration was 4.2 μg/L (102 μg/L) for BUP, 74.7 μg/L (580 μg/L) for NBUP, 0.9 μg/L (85.5 μg/L) for NAL, 159.5 μg/L (1370 μg/L) for BUP-G, 307.5 μg/L (1970 μg/L) for NBUP-G, and 79.6 μg/L (2310 μg/L) for NAL-G.