QT interval prolongation in patients on methadone with concomitant drugs

Substance Use Disorders and Medication-Assisted Therapies: Current Practices and Implications for Nursing

In the United States, the opioid epidemic and COVID-19-related substance use have exacerbated the overall incidence of substance use disorders (SUDs). Medication-assisted therapy (MAT), or cognitive and behavioral therapy that combines medications that reduce substance use or acute withdrawal symptoms, has dramatically improved outcomes for SUD patients, including preventing mortality. With recent US Congressional funding for MAT, patients presenting for acute care on MAT-related medications will continue to increase. Nurses should be aware of these medications' mechanism of action, typical side effects, and implications on treating acute pain to optimize their care.

Management of opioid withdrawal and initiation of medications for opioid use disorder in the hospital setting

Opioid use disorder (OUD) has become increasingly prevalent among hospitalized patients in the United States and globally. As its prevalence increases, this provides a valuable opportunity for clinicians in the hospital setting to engage and initiate management and treatment of OUD. This article aims to provide hospitalists and other clinicians working in the hospital with a narrative review of the management of opioid withdrawal and the initiation of medications for opioid use disorder (MOUD) in the hospital and provide an update on a novel low dose approach to buprenorphine induction (also commonly referred to as the "microinduction" method). Management can initially include treating withdrawal symptoms with opioids as well as with a combination of non-opioid medications such as alpha 2 agonists, benzodiazepines, and/or antiemetics as needed. Besides simply managing withdrawal symptoms, clinicians can further improve the care of patients with OUD through initiating maintenance treatment with MOUD, ideally with opioids used in the initial management of withdrawal. Opioid detoxification is an inferior method of primary treatment and is associated with relapse and poor outcomes. In contrast, treatment with MOUD using methadone or buprenorphine is associated with superior treatment outcomes and reduced relapse compared to detoxification alone. Treatment with MOUD using methadone or buprenorphine can be successfully used in the hospital setting. A novel low dose approach to buprenorphine induction may be useful in minimizing precipitated withdrawals in patients who have recently used or received opioids, which makes this an attractive option in the hospital where patients are frequently on opioids for acutely painful conditions. The hospital setting also provides a valuable opportunity for clinicians to address harm reduction in patients with OUD. Finally, clinicians can improve the long-term outcomes of patients with OUD by ensuring a smooth discharge with adequate and timely follow-up.

A Review of the Metabolism and Potential Drug-drug Interactions With Addictive Drugs

People who use drugs (PWUD) are at increased risk for drug-related harms such as overdose. Additionally, they are also at increased risk of secondary harms from bacterial and other infections such as hepatitis B, hepatitis C, and Human Immunodeficiency Virus. These secondary harms, along with other medical conditions, typically require treatment with prescription medications. When considering treatment options, drug-drug interactions (DDIs) must be considered, unfortunately these interactions are often overlooked with addictive drugs. Although DDIs in PWUD have been reviewed for certain drug classes and specific drugs of abuse, no comprehensive list could be found. The objective of this article is to compile a list of potential DDIs between prescription drugs and addictive drugs to create a list allowing prescribers to make more informed decisions when prescribing a medication to PWUD.

British Heart Rhythm Society Clinical Practice Guidelines on the Management of Patients Developing QT Prolongation on Antipsychotic Medication

The British Heart Rhythm Society’s Clinical Practice Guidelines on the Management of Patients Developing QT Prolongation on Antipsychotic Medication are written for heart rhythm consultants, primary care physicians, specialist registrars, nurses and physiologists who may be requested to review ECGs or advise on cases where antipsychotic-induced QT prolongation is suspected or proven. The guidance is adapted from the latest Maudsley Prescribing Guidelines in Psychiatry, published in 2018.

Opioids and Cardiac Arrhythmia: A Literature Review

OBJECTIVE

One of the most important side effects of opioids is their influence on the electrical activity of the heart. This review focusses on the effects of opioids on QT interval prolongation and their arrhythmogenic liability.

METHODS

By using various keywords, papers published up to 2018 in different databases were searched and identified. The search terms were opioids names, corrected QT interval, human-ether-a-go-go gene, torsades de pointes (TdP), cardiac arrhythmias, opioid dependence and other relevant terms. It emphasized the effects of each opioid agent alone on electrocardiogram (ECG) and some interactions.

RESULTS

Available data indicate that some opioids such as methadone are high-risk even at low doses, and have potential for prolongation of the QT interval and development of TdP, a dangerous ventricular tachycardia. A number of opioids such as tramadol and oxycodone are intermediate risk drugs and may develop long QT interval and TdP in high doses. Some other opioids such as morphine and buprenorphine are low-risk drugs and do not produce QT interval prolongation and TdP at least in routine doses. Opium-consumers are at higher risk of supra-ventricular arrhythmias, sinus bradycardia, cardiac block and atrial fibrillation.

CONCLUSION

The cardiac arrhythmogenicity of various opioids is different. Methadone has a higher capability to induce long QT interval and dangerous arrhythmias in conventional doses than others. To reduce of arrhythmogenic risk, high doses of opioids must be used cautiously with periodic monitoring of ECG in high-risk consumers such as patients under opioid maintenance treatment.

The Impact of Opioids on Cardiac Electrophysiology

Synthetic opioid agents have been used in modern medicine for over a century and for opioid addiction treatment for over a half-century. Liberal use of opioids in the United States has been attended by an extraordinary increase in opioid-related mortality, with over 16,000 deaths in 2012. As there have been advances in opioid agents for pain and addiction, so have there been advances in our understanding of the cardiac effects of these agents. In the last 10 years, significant data regarding electrophysiologic effects of these agents have been collected. We aim in this review to discuss the effects on cardiac electrophysiology of the various opioid agents currently in use and the evidence that these effects are contributing to the rise in opioid-related mortality.

Levorphanol use: past, present and future

Levorphanol is a potent opioid analgesic that was first approved for use in the United States in 1953. Levorphanol is approved for use in moderate to severe pain where an opioid analgesic is appropriate. Levorphanol has a wide range of activities including mu opioid agonism, delta agonism, kappa1 and kappa3 receptor agonism, N-methyl-d-aspartate receptor antagonism and reuptake inhibition of both norepinephrine and serotonin. This multimodal profile might prove effective for pain syndromes that are refractory to other opioid analgesics, such as central and neuropathic pain and opioid-induced hyperalgesia. Levorphanol is well suited as a first-line opioid and can also be used during opioid rotation. It has no known effect on the cardiac QT interval or drug-drug interactions involving hepatic cytochrome P450s enzymes. In these regards, levorphanol may offer a superior safety profile over methadone and other long-acting opioids. Despite its prospective value of multiple mechanisms of action and the potential for treating various types of pain, levorphanol use has been largely supplanted by other recently approved opioids. Its waning use over the years has caused it to be referred to as the "Forgotten Opioid" and resulted in what some consider its underutilization. In fact, levorphanol is relatively unfamiliar to most prescribers. The purpose of this review is to inform practitioners about the attributes of this opioid and reintroduce it to clinicians as an option for treating moderate to severe pain when alternative treatment options are inadequate, not indicated or contraindicated.

Perioperative analgesia and challenges in the drug-addicted and drug-dependent patient

The epidemic use of illicit drugs has led to an increasing number of patients with drug addiction and dependence presenting for perioperative care. There are a wide variety of drugs commonly abused including opioids, such as heroin and prescription drugs; stimulants, such as amphetamine and cocaine; depressant drugs, such as alprazolam and diazepam; and hallucinogens, such as lysergic acid diethylamide, phencyclidine, and marijuana. Treatment of opioid dependence by office-based buprenorphine and methadone maintenance programs has expanded opportunities for therapy. Treatment of these patients in the perioperative period is challenging. In addition to pain control, management of anxiety, psychological states, and hemodynamic control are the factors to be considered to provide optimum treatment. Although opioids are the mainstay for the control of acute pain, other therapeutic options include alternative routes of administration of local anesthetic, ketamine infusion, and the use of regional anesthesia. We discuss optimum perioperative management, the role of perioperative urine testing, and special considerations in patients on methadone and buprenorphine.

Functional genetic polymorphisms in CYP2C19 gene in relation to cardiac side effects and treatment dose in a methadone maintenance cohort

Abstract Methadone maintenance therapy is an established treatment for heroin dependence. This study tested the influence of functional genetic polymorphisms in CYP2C19 gene encoding a CYP450 enzyme that contributes to methadone metabolism on treatment dose, plasma concentration, and side effects of methadone. Two single nucleotide polymorphisms (SNPs), rs4986893 (exon 4) and rs4244285 (exon 5), were selected and genotyped in 366 patients receiving methadone maintenance therapy in Taiwan. The steady-state plasma concentrations of both methadone and its EDDP metabolite enantiomers were measured. SNP rs4244285 allele was significantly associated with the corrected QT interval (QTc) change in the electrocardiogram (p=0.021), and the Treatment Emergent Symptom Scale (TESS) total score (p=0.021) in patients who continued using heroin, as demonstrated with a positive urine opiate test. Using the gene dose (GD) models where the CYP2C19 SNPs were clustered into poor (0 GD) versus intermediate (1 GD) and extensive (2 GD) metabolizers, we found that the extensive metabolizers required a higher dose of methadone (p=0.035), and showed a lower plasma R-methadone/methadone dose ratio (p=0.007) in urine opiate test negative patients, as well as a greater QTc change (p=0.008) and higher total scores of TESS (p=0.018) in urine opiate test positive patients, than poor metabolizers. These results in a large study sample from Taiwan suggest that the gene dose of CYP2C19 may potentially serve as an indicator for the plasma R-methadone/methadone dose ratio and cardiac side effect in patients receiving methadone maintenance therapy. Further studies of pharmacogenetic variation in methadone pharmacokinetics and pharmacodynamics are warranted in different world populations.

QT interval screening in methadone maintenance treatment: report of a SAMHSA expert panel

In an effort to enhance patient safety in opioid treatment programs, the Substance Abuse and Mental Health Saervices Administration convened a multi-disciplinary Expert Panel on the Cardiac Effects of Methadone. Panel members (Appendix A) reviewed the literature, regulatory actions, professional guidances, and opioid treatment program experiences regarding adverse cardiac events associated with methadone. The Panel concluded that, to the extent possible, every opioid treatment program should have a universal Cardiac Risk Management Plan (incorporating clinical assessment, electrocardiogram assessment, risk stratification, and prevention of drug interactions) for all patients and should strongly consider patient-specific risk minimization strategies (such as careful patient monitoring, obtaining electrocardiograms as indicated by a particular patient's risk profile, and adjusting the methadone dose as needed) for patients with identified risk factors for adverse cardiac events. The Panel also suggested specific modifications to informed consent documents, patient education, staff education, and methadone protocols.

QT interval prolongation: prevalence, risk factors and pharmacovigilance data among methadone-treated patients in France

Several reports have suggested the role of methadone in QT prolongation, Torsades de Pointes (TdP), and ventricular arrhythmia. The aim of this study was to identify the frequency of QT interval prolongation and QT dispersion among a population of addict patients treated with methadone, completed by the description of cardiac events reported to the French pharmacovigilance system. QT interval (corrected with the Bazett's method) and dispersion were measured on a cohort of patients treated with methadone during their visit to addiction specialized centers in Southwest of France. Whenever possible, methadone blood concentrations were measured. In addition, reports concerning methadone were searched in the French Pharmacovigilance database from 1996 to 2007. The cohort included 42 patients with mean QTc length of 414.3 ± 28.5 ms and mean QT dispersion of 66.0 ± 41.1 ms. None of the patient presented a QTc above 500 ms. These values were higher in patients with recent increase in methadone dose, use of tobacco or drugs prolonging QT, and history of cardiac disease. We found five cases of QT prolongation (3 TdP) and seven cases of sudden deaths in the French pharmacovigilance database (2.2% of methadone reports). Most of these events occurred after introducing methadone or another drug potentially interacting with methadone. Methadone can prolong the QT interval at dose usually used for addiction maintenance treatment in France. A cardiac evaluation, with at least a systematic ECG, could be useful during methadone treatment, particularly in case of recent modification of the regimen.

Retrospective analysis of low-dose methadone and QTc prolongation in chronic pain patients

Background

Methadone is a synthetic opioid that is widely used for the treatment of chronic pain. The association between methadone treatment and QT interval prolongation or which can lead to torsades de pointes has been confirmed with larger studies on high dose methadone. The aim of this study was to determine the effect of methadone on the QTc interval in patients, whether the daily dose of methadone should be lower than what has been previously investigated.

Methods

A total of 130 patients were included, with 90 patients in the methadone group and 40 patients in the control group. For each ECG, heart rate, QT interval and corrected QT (QTc) interval were recorded. The patient demographics, methadone dose and serum level, duration of methadone use and past medical history were collected.

Results

The QTc interval was significantly longer in the treatment group than in the control group (443 ± 30.0 ms versus 408 ± 28.0 ms, respectively, P < 0.0001) and more patients in the treatment group had a QTc interval greater than 450 ms (36.7% versus 7.5%, respectively, P = 0.0005). The QTc interval was not associated with methadone dose P = 0.9278), serum level (P = 0.2256) or duration of treatment (P = 0.1822).

Conclusions

This study has shown that methadone use is associated with longer QTc intervals, even among patients with daily doses of less than 80 mg. In this study, no correlation was found between QTc duration and methadone dose, serum levels or duration of use. However, the magnitude of the QTc interval was associated with female gender and the use of antidepressants.

Cardiotoxicity of Oral Methadone as an Analgesic–-Recommendations for Safe Use

Once used only as third-line therapy in the management of chronic pain states, methadone is now being used as first- and second-line therapy. Most risks and the stigma associated with methadone use have been known for years. Only over the past decade or so have the unique pharmacokinetic-pharmacodynamic properties and methods for conversion from other opioids to methadone been established. Pertinent English-language literature was obtained from MEDLINE/PUBMED and EMBASE searches (1966-June 2009). This paper provides an overview of the cardiotoxicity of oral methadone, with an emphasis on its use as an analgesic. Cardiotoxicity during its use in the maintenance of opioid addiction has also been reviewed due to the wealth of epidemiologic, risk factor, and correlative analytic data contained therein. A series of recommendations are provided to improve the cardiac safety profile of oral methadone used for analgesia. In addition, there is a discussion of settings and patient types which may impact upon these recommendations.

Prevalence of long QTc interval in methadone maintenance patients

BACKGROUND

There is a concern about cardiac rhythm disorders related to QTc interval prolongation induced by methadone. A cross-sectional study was designed to evaluate the prevalence of long QTc (LQTc) interval in patients in methadone maintenance treatment (MMT) and risk factors for LQTc.

METHODS

The study population included 109 subjects (74 males, median age 43 years). Socio-demographic and toxicological variables were recorded, as well as concomitant use of drugs related with QT prolongation, history of heart diseases, and corrected QT interval by heart rate (QTc) in the ECG. Plasma concentrations of (R)-methadone and (S)-methadone enantiomers were determined in 69 subjects.

RESULTS

Ten patients (9.2%) presented a QTc above 440 ms but a QTc above 500 ms was observed in only 2 (1.8%). Patients with QTc above 440 ms compared with the remaining subjects were older (median [25th-75th percentile range]: 49 [39-56] years vs. 37 [33-43]; Wilcoxon's W=217.5, p=0.002) and took a higher daily dose of methadone (median [25th-75th percentile range]: 120 [66-228] mg/day vs. 60 [40-110] mg/day; W=298.5, p=0.037). Methadone dose correlated with QTc interval (Pearson's r(2)=0.291, p=0.002). Patients with and without long QTc showed no differences in plasma concentrations of (R)-methadone and (S)-methadone enantiomers.

CONCLUSIONS

The prevalence of LQTc was 9.2%. An association between LQTc and methadone doses was observed but the relationship with plasma concentrations of methadone enantiomers is unclear.

Ciprofloxacin-induced torsades de pointes in a methadone-dependent patient

ABSTRACT Background Methadone has been associated with QT prolongation and Torsades de pointes. Ciprofloxacin may prolong QT interval and induce Torsades de pointes when other risk factors are present. Case description A case is described in which a patient receiving methadone treatment developed Torsades de pointes following the addition of ciprofloxacin. Conclusion Ciprofloxacin should be used with caution in patients receiving methadone.

Actual and potential drug interactions associated with methadone

OBJECTIVE

To identify and characterize methadone-related drug interactions, as well as factors accounting for the variability in manifesting these interactions clinically.

DESIGN

Systematic review of the primary literature.

METHODS

Over 200 articles, reports of clinical trials, and case reports were reviewed. Studies and case reports were included if they revealed either quantitative or qualitative methods to identify, evaluate severity of, or compare methadone-related drug interactions.

RESULTS OF DATA SYNTHESIS

The evidence base associated with methadone drug interactions is underdeveloped in general, as the majority of references found were case reports or case series. Most of the studies and reports focused on inpatients receiving methadone maintenance treatment (MMT) that were between 20 and 60 years of age, taking 200 mg/day of methadone or less. Evidence supporting the involvement of lesser known cytochrome P450 enzymes such as 2B6 is emerging, which may partially explain the inconsistencies previously found in studies looking specifically at 3A4 in vitro and in vivo. Genetic variability may play a role in the pharmacokinetics and pharmacodynamics of many medications, including methadone.

CONCLUSIONS

Drug interactions associated with methadone and their clinical significance are still poorly understood in general. Many tertiary drug information references and review articles report interactions associated with methadone in a general sense, much of which is theoretical and not verified by case reports, much less well-designed clinical trials. The majority of drug interaction reports that do exist were performed in the MMT population, which may differ significantly from chronic pain or cancer pain populations.

Methadone death, dosage and torsade de pointes: risk-benefit policy implications

Methadone maintenance treatment (MMT) for opioid dependency has consistently shown important heath, social and legal benefits. What started as a small experimental program in Lexington, Kentucky has grown and expanded substantially over 35 years. Its practice is now well established both in specialized centers and in the broader community. In society, methadone deaths represent an important issue of public safety: methadone diversion to and ingestion by nontolerant individuals outside of treatment. Within treatment, methadone deaths occur most commonly in the early stabilization period (due to issue of tolerance), in periods of transition, or among certain individuals who abuse other substances (opioids, benzodiazepines, or alcohol). Research suggests moderately high methadone dosages help improve patient retention. Results from pharmacodynamic, kinetic and stereospecific studies continue to support the importance of individualizing dose. For some patients, much larger doses may be necessary to fully achieve all pharmacotherapy goals of treatment. Practitioners must be cautious however as certain patients on higher dosages are predisposed to torsade de pointes and increased mortality. Policymakers have a responsibility in their decision-making to balance the quality of life benefits for patients within MMT with the risks of increased mortality both for individuals within treatment and the general public.

Stereoselective Block of hERG Channel by (S)-Methadone and QT Interval Prolongation in CYP2B6 Slow Metabolizers

Methadone inhibits the cardiac potassium channel hERG and can cause a prolonged QT interval. Methadone is chiral but its therapeutic activity is mainly due to (R)-methadone. Whole-cell patch-clamp experiments using cells expressing hERG showed that (S)-methadone blocked the hERG current 3.5-fold more potently than (R)-methadone (IC50s (half-maximal inhibitory concentrations) at 37 degrees C: 2 and 7 microM). As CYP2B6 slow metabolizer (SM) status results in a reduced ability to metabolize (S)-methadone, electrocardiograms, CYP2B6 genotypes, and (R)- and (S)-methadone plasma concentrations were obtained for 179 patients receiving (R,S)-methadone. The mean heart-rate-corrected QT (QTc) was higher in CYP2B6 SMs (*6/*6 genotype; 439+/-25 ms; n=11) than in extensive metabolizers (non *6/*6; 421+/-25 ms; n=168; P=0.017). CYP2B6 SM status was associated with an increased risk of prolonged QTc (odds ratio=4.5, 95% confidence interval=1.2-17.7; P=0.03). This study reports the first genetic factor implicated in methadone metabolism that may increase the risk of cardiac arrhythmias and sudden death. This risk could be reduced by the administration of (R)-methadone.

Corrected-QT intervals as related to methadone dose and serum level in methadone maintenance treatment (MMT) patients: a cross-sectional study

AIMS

To determine and evaluate QTc intervals in electrocardiograms (ECGs) of former heroin addicts, currently in methadone maintenance treatment (MMT), as previous reports suggest that methadone may prolong QTc intervals, thus possibly increasing the risk for Torsade de pointes (TdP).

DESIGN

Cross-sectional study.

SETTING

Between January 2003 and September 2004, patients on a steady dose of methadone for at least 2 weeks were studied.

PARTICIPANTS

This study is a subset of 153 patients, of whom 151 patients participated in a study of high methadone doses and serum levels. A total of 138 patients in MMT for a minimum of 100 days up to 10.7 years, receiving 40-290 mg/day methadone dose, participated.

MEASUREMENTS

Patients had an ECG at the time when blood was drawn for determination of serum methadone levels at around 24 hours after the last oral methadone dose. Corrected-QT intervals (QTc) were calculated using the Bazett formula.

FINDINGS

Of 138 patients studied, 98 (71%) were male. Mean QTc interval was 418.3 +/- 32.8 milliseconds (ms). Mean methadone dose was 170.9 +/- 50.3 mg/day and mean serum methadone level was 708.2 +/- 363.1 ng/ml. Methadone dose and serum levels did not correlate with QTc. Three patients had QTc intervals above 500 ms ('prolonged'). After 2 +/- 0.4 years of follow-up, two patients died; they were two of three patients with very prolonged QTc. Causes of death were not attributed to cardiac origin. An additional 19 patients had QTc intervals of between 450 and 499 ms ('possibly prolonged'). None of these QTc > or = 450 ms patients had any cardiac problems. Methadone doses of all 22 patients were > 120 mg/day.

CONCLUSIONS

Methadone maintenance is generally safe; however, the possible toxicity of high dose (> 120 mg/day) should be monitored for QTc.

Methadone-associated Torsades de Pointes (polymorphic ventricular tachycardia) in opioid-dependent patients

AIMS

We reviewed all the publications concerning methadone-associated Torsades de Pointes (TdP) (polymorphic ventricular tachycardia) in opioid-dependent patients in order to characterize the clinical circumstances leading to this serious complication.

METHODS

Our literature search yielded 14 reports on 40 patients with methadone-associated TdP. We gathered and recorded the risk factors for TdP mentioned in those reports, among other clinical aspects.

RESULTS

The most prevalent risk factors for TdP were high-dose methadone (n = 39, 97.5%) and concomitant use of agents that increase serum methadone levels or trigger TdP (n = 22, 55%). HIV infection (n = 16), hypokalaemia (n = 14), female sex (n = 13), liver cirrhosis or renal failure (n = 11) and heart disease (n = 9) were also described. All the patients had at least one and 34 (85%) had two or more risk factors for TdP during methadone treatment.

CONCLUSIONS

We wish to raise the level of awareness of risk factors for TdP among physicians in heroin-treatment clinics who frequently prescribe methadone.

Addiction – who is not affected?

Addiction and addiction-related behaviour increased during the past decades. Several substances with psychoactive attributes, like opioids, cocaine or alcohol, can lead to dependence with physical and/or mental symptoms. In addition to substance-related addiction, non-substance-related dependence requires special attention. Increasing numbers of workaholics and patients suffering from internet-addiction, gambling or eating-disorders can be observed. To meet international treatment standards for addiction, diversification of therapy is necessary and, additionally, gender-related aspects in development and treatment of dependence and addiction-related behaviour are essential for state-of-the-art therapy of this patient population.

Methadone doses of 100 mg or greater are more effective than lower doses at suppressing heroin self-administration in opioid-dependent volunteers

AIMS

Methadone maintenance has been an effective pharmacotherapy for the treatment of heroin dependence for nearly four decades. Recent clinical research suggests that methadone doses larger than those used in most clinics are more effective at suppressing illicit heroin use. This greater efficacy may result from greater cross-tolerance to the reinforcing effects of heroin.

DESIGN

The purpose of this double-blind, within-subject study was to examine the relationship between methadone maintenance dose and the reinforcing effects of heroin.

SETTING

Participants were stabilized on 50, 100 and 150 mg methadone (ascending order) during separate outpatient periods before being admitted to an inpatient research unit for testing at each maintenance dose.

PARTICIPANTS

Five opiate-dependent volunteers completed the study.

MEASUREMENTS

During each 4-week inpatient testing period, participants sampled three doses of heroin (0, 10, or 20 mg; random order; one dose per week) and were subsequently allowed seven opportunities to choose between another injection of that week's heroin dose and varying amounts of money (dollars 2-38).

FINDINGS

The number of heroin injections chosen decreased as methadone dose was increased. Larger alternative monetary reinforcers were required to suppress heroin self-administration during maintenance on 50 compared to 100 or 150 mg methadone. Larger methadone doses also completely blocked the subjective effects of heroin and produced greater withdrawal suppression during the outpatient periods.

CONCLUSIONS

These results support other clinical and laboratory-based research indicating that persistent heroin use may be reduced by providing larger methadone maintenance doses that produce more effective cross-tolerance to heroin.

Effects of Buprenorphine on Cardiac Repolarization in a Patient with Methadone-Related Torsade de Pointes

Torsade de pointes is a rare but potentially fatal ventricular arrhythmia that is often triggered by drugs that prolong the rate-corrected QT (QTc) interval. This arrhythmia has been attributed to levacetylmethadol and methadone, synthetic opioids used to treat heroin addiction. Levacetylmethadol, a derivative of methadone, is being withdrawn from the United States market because its use waned after a black box warning was issued to require electrocardiographic monitoring. Therefore, methadone and buprenorphine are the only opioids available for the treatment of heroin addiction. To our knowledge, the cardiac safety of buprenorphine in patients with methadone-related QTc prolongation has not been described. We report a patient who developed torsade de pointes while receiving high-dose methadone and was successfully inducted onto buprenorphine under close medical supervision. No clinically important QTc prolongation was observed in the acute setting or during follow-up. This observation suggests that buprenorphine may be a safe alternative to oral methadone in patients with opioid addiction who develop torsade de pointes.