The Use of the Methadone/Metabolite Ratio (MMR) to Identify an Individual Metabolic Phenotype and Assess Risks of Poor Response and Adverse Effects: Towards Scientific Methadone Dosing

Effect of CYP2D6, 2C19, and 3A4 Phenoconversion in Drug-Related Deaths

Molecular autopsy is a very important tool in forensic toxicology. However, many determinants, such as co-medication and physiological parameters, should be considered for optimal results. These determinants could cause phenoconversion (PC), a discrepancy between the real metabolic profile after phenoconversion and the phenotype determined by the genotype. This study's objective was to assess the PC of drug-metabolizing enzymes, namely CYP2D6, 2C19, and 3A4, in 45 post-mortem cases where medications that are substrates, inducers, or inhibitors of these enzymes were detected. It also intended to evaluate how PC affected the drug's metabolic ratio (MR) in four cases. Blood samples from 45 cases of drug-related deaths were analyzed to detect and determine drug and metabolite concentrations. Moreover, all the samples underwent genotyping utilizing the HaloPlex Target Enrichment System for CYP2D6, 2C19, and 3A4. The results of the present study revealed a statistically significant rate of PC for the three investigated enzymes, with a higher frequency of poor metabolizers after PC. A compatibility was seen between the results of the genomic evaluation after PC and the observed MRs of venlafaxine, citalopram, and fentanyl. This leads us to focus on the determinants causing PC that may be mainly induced by drug interactions. This complex phenomenon can have a significant impact on the analysis, interpretation of genotypes, and accurate conclusions in forensic toxicology. Nevertheless, more research with more cases in the future is needed to confirm these results.

A Survey of the Status of Methadone Switching in Japan Using a Hospital-Based Administrative Claims Database

Methadone is generally used for the management of cancer pain in patients who cannot obtain adequate analgesia from other strong opioids; however, it has a complicated and inconsistent conversion ratio from pre-switching opioid dosage to methadone. This issue may be pronounced in Japan because only oral tablets are commercially available. We aimed to elucidate the status of methadone switching in Japan, focusing on its dosage. Using a Japanese hospital-based administrative claims database, we included patients who switched to methadone between April 2008 and January 2021. The proportion of methadone switching completion that required more than the defined conversion ratio in the Japanese package insert (called "high-dose methadone switching") was evaluated as a primary endpoint. Other endpoints included "the duration from initiation to completion of methadone switching" and "factors affecting high-dose methadone switching by using multivariate logistic regression analysis". Of 1585 patients who received methadone, 370 were enrolled. Among those, 130 (35.1%) received high-dose methadone switching. The median duration of methadone switching completion (12 days) was longer in the high-dose methadone switching group than in other patients. Four variables were identified as factors affecting high-dose methadone switching. Younger age and outpatient status increased the risk of requiring high-dose methadone switching, whereas the concomitant use of nonsteroidal anti-inflammatory drugs and fentanyl as a pre-switching opioid decreased the risk. In conclusion, more than 30% of the patients underwent high-dose methadone switching and required long completion periods, suggesting that methadone switching remains challenging in Japan.

Methadone and neonatal abstinence syndrome (NAS): what we think we know, but do not

Since the first use of methadone to treat OUD in pregnancy in the 1970s, there has been a long, controversial, and confusing history of studies, regulatory actions, and practice changes that have clouded an accurate perception of methadone's use in pregnancy. This review will trace this history with a focus on the effect of methadone exposure during pregnancy on neonatal abstinence syndrome (NAS). A new laboratory measure, the serum methadone/metabolite ratio (MMR), has provided a tool for documenting the profoundly dynamic nature of perinatal metabolism. Continuous induction of metabolic enzymes during pregnancy requires dose adjustments and dose frequency changes. The concept of "fetal methadone dosing" emphasizes that relative stability of methadone levels in the fetus is an important consideration for methadone dosing in pregnancy. Finally, the effects of the societal "war on drugs" on pediatric management of neonatal withdrawal risks will be discussed, as well as the importance of comprehensive services for mother and child including the "rooming-in" approach of neonatal care which has considerably replaced the older NICU care model of maternal/infant separation.

Accelerated Fentanyl Metabolism During Pregnancy and Impact on Prenatal Drug Testing

OBJECTIVE

To evaluate the metabolic pattern of illicit fentanyl in a sample of pregnant patients with opioid use disorder. Fentanyl pharmacokinetics during pregnancy are currently understudied yet the interpretation of a fentanyl immunoassay during pregnancy has significant implications on maternal legal custody and child welfare. Through this medical-legal lens, we demonstrate the utility of an emerging metric, the metabolic ratio, for accurate analysis of fentanyl pharmacokinetics during pregnancy.

METHODS

We conducted a retrospective cohort analysis using the electronic medical records of 420 patients receiving integrated prenatal and opioid use disorder care at a large urban safety net hospital. Data related to maternal health and substance use were collected for each subject. The metabolic ratio was calculated for each subject to measure their rate of metabolism. The sample's (n = 112) metabolic ratios were compared with a large non-pregnant sample (n = 4366).

RESULTS

The metabolic ratios of our pregnant sample were significantly (p = .0001) higher than the metabolic ratios of our non-pregnant sample, indicating that the rate of conversion to the major metabolite was faster in pregnant people. The effect size for this difference between the pregnant and non-pregnant sample was large (d = 0.86).

CONCLUSIONS FOR PRACTICE

Our findings characterize the unique metabolic pattern of fentanyl in pregnant people who use opioids, providing guidance for institutional policies around fentanyl drug testing. Additionally, our study warns of misinterpretation of toxicology results and stresses the importance of physician advocacy on behalf of pregnant women who use illicit opioids.

The impact of relaxing restrictions on take-home doses during the COVID-19 pandemic on program effectiveness and client experiences in opioid agonist treatment: a mixed methods systematic review

BACKGROUND

The COVID-19 pandemic led to an unprecedented relaxation of restrictions on take-home doses in opioid agonist treatment (OAT). We conducted a mixed methods systematic review to explore the impact of these changes on program effectiveness and client experiences in OAT.

METHODS

The protocol for this review was registered in PROSPERO (CRD42022352310). From Aug.-Nov. 2022, we searched Medline, Embase, CINAHL, PsycInfo, Web of Science, Cochrane Register of Controlled Trials, and the grey literature. We included studies reporting quantitative measures of retention in treatment, illicit substance use, overdose, client health, quality of life, or treatment satisfaction or using qualitative methods to examine client experiences with take-home doses during the pandemic. We critically appraised studies using the Mixed Methods Appraisal Tool. We synthesized quantitative data using vote-counting by direction of effect and presented the results in harvest plots. Qualitative data were analyzed using thematic synthesis. We used a convergent segregated approach to integrate quantitative and qualitative findings.

RESULTS

Forty studies were included. Most were from North America (23/40) or the United Kingdom (9/40). The quantitative synthesis was limited by potential for confounding, but suggested an association between take-home doses and increased retention in treatment. There was no evidence of an association between take-home doses and illicit substance use or overdose. Qualitative findings indicated that take-home doses reduced clients' exposure to unregulated substances and stigma and minimized work/treatment conflicts. Though some clients reported challenges with managing their medication, the dominant narrative was one of appreciation, reduced anxiety, and a renewed sense of agency and identity. The integrated analysis suggested reduced treatment burden as an explanation for improved retention and revealed variation in individual relationships between take-home doses and illicit substance use. We identified a critical gap in quantitative measures of patient-important outcomes.

CONCLUSION

The relaxation of restrictions on take-home doses was associated with improved client experience and retention in OAT. We found no evidence of an association with illicit substance use or overdose, despite the expansion of take-home doses to previously ineligible groups. Including patient-important outcome measures in policy, program development, and treatment planning is essential to ensuring that decisions around take-home doses accurately reflect their value to clients.

Individualizing methadone treatment with split dosing: An underutilized tool

Methadone's long half-life typically allows for once daily dosing. However, a growing body of evidence and clinical experience shows that some patients may benefit from twice-daily ("split") dosing to produce more stable symptoms and minimize side effects, independent of serum peak-to-trough levels. Concerns regarding split dosing typically center on diversion and poor adherence and must be taken seriously. However, policy changes during COVID-19 demonstrate that the rigidity historically applied to methadone may be unnecessarily stringent. Given clinical advances and policy updates, we believe clinicians should weigh the risks and benefits of this underutilized tool for select patients, as we await the evidence-based recommendations our patients deserve.

Predictors of the Rate of Illicit Fentanyl Metabolism in a Cohort of Pregnant Individuals

INTRODUCTION

Illicit fentanyl use is growing in the United States, including among pregnant persons. Despite the prevalence of illicit fentanyl in the drug supply, the pharmacokinetics of fentanyl remains understudied, especially for pregnant individuals. The variability of fentanyl pharmacokinetics influences detection of fentanyl in urine samples, the results of which can have significant legal consequences. For pregnant and parenting individuals, these legal consequences may include termination of parental rights.

METHODS

Through this medical-legal lens, we conducted a retrospective cohort analysis using the electronic medical records of women receiving integrated prenatal care and substance use disorder treatment. A total of 420 medical records were reviewed and 112 individuals who had a positive fentanyl immunoassay and met the selection criteria were included. Metabolic ratios (level of norfentanyl/level of fentanyl) were calculated for each study individual. A linear regression analysis was used to determine if the following physiologic factors were predictors of the rate of fentanyl metabolism: hepatic function, renal function, body mass index, medication dosage, gestational age, and maternal age.

RESULTS

Results indicated that advanced maternal age predicted a slower conversion of fentanyl to norfentanyl, whereas increased gestational age predicted a faster conversion.

CONCLUSIONS

Variations in fentanyl metabolism in pregnancy highlight the importance of clinician vigilance when interpreting fentanyl rests results, especially for individuals with advancing maternal age. In such cases, clinician caution and advocacy may prevent unwarranted and unjust removal of a child from maternal custody.

Lower buprenorphine elimination rate constant is associated with lower opioid use

BACKGROUND

Opioid craving is suggested to correlate with the rate of reduction in buprenorphine (BUP) plasma levels. No studies explored Buprenorphine elimination rate constant (BUP EL.R) as a predictor of opioid use or retention in BUP treatment.

METHODS

Analysis was performed using data from a randomized controlled trial of 141 adults with opioid use disorder (OUD) randomized to Incentivized Adherence and Abstinence monitoring (I-AAM; experimental (n = 70) and treatment-as-usual; control (n = 71). In the I-AAM, structured access to unsupervised BUP doses was provided up to 28 days contingent of adherence measured by Therapeutic Drug Monitoring and abstinence by Urinary Drug Screens (UDS). In contrast, the treatment-as-usual (control) provided unstructured access to unsupervised doses was provided for up to 14 days considering UDS results. The primary outcome was percentage negative UDS. The secondary outcome, retention in treatment, was continuous enrollment in the study and analysis was via intention-to-treat. Significant bivariate correlations with the outcomes were adjusted for group allocation.

RESULTS

A significant negative correlation between BUP EL.R and percentage negative opioid screens (Pearson correlation coefficient - 0.57, p < 0.01) was found. After adjusting for trial group, BUP EL.R was shown to be an independent predictor of percentage negative opioid screens (Standardized Beta Coefficient - 0.57, 95% CI - 221.57 to - 97.44, R² 0.322).

CONCLUSION

BUP EL.R predicted 32.2% of the variation in percentage negative opioid UDS and may serve as a potential promising tool in precision medicine of BUP treatment. Higher buprenorphine elimination is associated with higher positive opioid urine screens during treatment.

TRIAL REGISTRATION

ISRCTN41645723 retrospectively registered on 15/11/2015.

Exploring the Potential of Implementing Managed Alcohol Programmes to Reduce Risk of COVID-19 Infection and Transmission, and Wider Harms, for People Experiencing Alcohol Dependency and Homelessness in Scotland

People who experience homelessness and alcohol dependency are more vulnerable than the general population to risks/harms relating to COVID-19. This mixed methods study explored stakeholder perspectives concerning the impact of COVID-19 and the potential utility of introducing managed alcohol programmes (MAPs) in Scotland as part of a wider health/social care response for this group. Data sources included: 12 case record reviews; 40 semi-structured qualitative interviews; and meeting notes from a practitioner-researcher group exploring implementation of MAPs within a third sector/not-for-profit organisation. A series of paintings were curated as a novel part of the research process to support knowledge translation. The case note review highlighted the complexity of health problems experienced, in addition to alcohol dependency, including polysubstance use, challenges related to alcohol access/use during lockdown, and complying with stay-at-home rules. Qualitative analysis generated five subthemes under the theme of ‘MAPs as a response to COVID-19′: changes to alcohol supply/use including polysubstance use; COVID-19-related changes to substance use/homelessness services; negative changes to services for people with alcohol problems; the potential for MAPs in the context of COVID-19; and fears and concerns about providing MAPs as a COVID-19 response. We conclude that MAPs have the potential to reduce a range of harms for this group, including COVID-19-related harms.

COVID-19 and Substance Use Disorders: Recommendations to a Comprehensive Healthcare Response. An International Society of Addiction Medicine Practice and Policy Interest Group Position Paper

Coronavirus Disease 2019 (COVID-19) is escalating all over the world and has higher morbidities and mortalities in certain vulnerable populations. People Who Use Drugs (PWUD) are a marginalized and stigmatized group with weaker immunity responses, vulnerability to stress, poor health conditions, high-risk behaviors, and lower access to health care services. These conditions put them at a higher risk of COVID-19 infection and its complications. In this paper, an international group of experts on addiction medicine, infectious diseases, and disaster psychiatry explore the possible raised concerns in this issue and provide recommendations to manage the comorbidity of COVID-19 and Substance Use Disorder (SUD).