Psychotropic drugs and the ECG: focus on the QTc interval

QT Interval, Antipsychotics and Correlates Among Patients with Schizophrenia: Cross-Sectional Data from the Multicentric Real-World FACE-SZ

BACKGROUND

The life expectancy of patients with schizophrenia is reduced, partly due to cardiovascular diseases. Antipsychotics are associated with QT interval prolongation, which is a risk factor for arrhythmia and cardiac arrest. The differences between antipsychotic with regard to QT interval prolongation are not well understood.

OBJECTIVE

The aim was to compare the QT values associated with different antipsychotics within a real-world population of subjects with clinically stable forms of schizophrenia.

METHODS

The FACE-SZ cohort comprises subjects with psychotic disorders, referred to schizophrenia expert cents. QT interval was measured, as well as all treatments (psychotropic and others). The following maintenance treatment for schizophrenia was analysed cross-sectionally: aripiprazole, clozapine, haloperidol, amisulpride, olanzapine, quetiapine, risperidone. Age, sex, smoking status, body mass index, blood potassium levels, and the co-prescription of another QT-prolonging treatment were used as adjustment factors in multivariable linear regression analyses.

RESULTS

Among 792 patients, the mean corrected QT (QTc) interval in the sample of patients under monotherapy was 407 ms. The mean age was 31.7 years, and the majority were male (73.3 %). In comparison to the rest of the sample, clozapine was associated with a longer QTc interval (β = 0.012, 95% CI [0.006-0.018]), while aripiprazole was significantly associated with a shorter QTc interval (β = - 0.010, 95% CI [- 0.016 to - 0.005]). Other antipsychotics were not associated with significant variations of the QTc.

CONCLUSIONS

The prescription of antipsychotics should always be accompanied by close monitoring of the QTc interval to prevent the risk of severe cardiac arrhythmia, particularly concerning clozapine.

Psychological Outcomes and Interventions for Individuals With Congenital Heart Disease: A Scientific Statement From the American Heart Association

Although resilience and high quality of life are demonstrated by many individuals with congenital heart disease, a range of significant psychological challenges exists across the life span for this growing patient population. Psychiatric disorders represent the most common comorbidity among people with congenital heart disease. Clinicians are becoming increasingly aware of the magnitude of this problem and its interplay with patients’ physical health, and many seek guidance and resources to improve emotional, behavioral‚ and social outcomes. This American Heart Association scientific statement summarizes the psychological outcomes of patients with congenital heart disease across the life span and reviews age-appropriate mental health interventions, including psychotherapy and pharmacotherapy. Data from studies on psychotherapeutic, educational‚ and pharmacological interventions for this population are scarce but promising. Models for the integration of mental health professionals within both pediatric and adult congenital heart disease care teams exist and have shown benefit. Despite strong advocacy by patients, families‚ and health care professionals, however, initiatives have been slow to move forward in the clinical setting. It is the goal of this scientific statement to serve as a catalyst to spur efforts for large-scale research studies examining psychological experiences, outcomes, and interventions tailored to this population and for integrating mental health professionals within congenital heart disease interdisciplinary teams to implement a care model that offers patients the best possible quality of life.

Depression and the use of antidepressants in cardiovascular diseases from a cardiologist’s perspective

Introduction: Cardiovascular diseases, especially coronary heart disease or heart failure, are often chronic.

Aim and method: The aim of this study was to review the literature on the prevalence of depressive disorders and the use of antidepressants in cardiovascular disease. For this purpose, articles available in PubMed and Google Scholar databases were used.

Results: About one in five patients with cardiovascular disease suffers from major depressive disorder. Psychosocial stress, depression and anxiety, are associated with poorer prognosis and make it more difficult for patients to make positive lifestyle changes and comply with medical recommendations. Conversely, depressive symptoms are associated with an increased risk of cardiovascular incidents. Regarding pharmacotherapy, selective serotonin reuptake inhibitors (SSRIs) are considered safe drugs, while tricyclic antidepressants are not recommended. In the treatment of depression and cardiovascular diseases, supplementation or a diet rich in omega-3 fatty acids is worth mentioning.

Conclusions: The above literature review highlights the need for a multidirectional approach that is essential to diagnose, understand and then treat these, often comorbid, conditions of cardiovascular disease and depression.

Antipsychotics cardiotoxicity: What's known and what's next

Chronic use of antipsychotic medications entails a dilemma between the benefit of alleviating psychotic symptoms and the risk of troubling, sometimes life-shortening adverse effects. Antipsychotic-induced cardiotoxicity is one of the most life-threatening adverse effects that raises widespread concerns. These cardiotoxic effects range from arrhythmia to heart failure in the clinic, with myocarditis/cardiomyopathy, ischemic injuries, and unexplained cardiac lesions as the pathological bases. Multiple mechanisms have been proposed to underlie antipsychotic cardiotoxicity. This review aims to summarize the clinical signs and pathological changes of antipsychotic cardiotoxicity and introduce recent progress in understanding the underlying mechanisms at both the subcellular organelle level and the molecular level. We also provide an up-to-date perspective on future clinical monitoring and therapeutic strategies for antipsychotic cardiotoxicity. We propose that third-generation antipsychotics or drug adjuvant therapy, such as cannabinoid receptor modulators that confer dual benefits - i.e., alleviating cardiotoxicity and improving metabolic disorders - deserve further clinical evaluation and marketing.

A Dynamically Reconfigurable ECG Analog Front-End With a 2.5× Data-Dependent Power Reduction

This paper presents a reconfigurable electrocardiogram (ECG) analog front-end (AFE) exploiting bio-signals' inherent low activity and quasi-periodicity to reduce power consumption. This is realized by an agile, on-the-fly dynamic noise-power trade-off performed over specific cardiac cycle regions guided by a least mean squares (LMS)-based adaptive predictor leading to ∼2.5× data-dependent power savings. Implemented in 65 nm CMOS, the AFE has tunable performance exhibiting an input-referred noise ranging from 2.38 - 3.64 μV_rms while consuming 307 - 769 nW from a 0.8 V supply. A comprehensive system performance verification was performed using ECG records from standard databases to establish the feasibility of the proposed predictor-based approach for power savings without compromising the system's anomaly detection capability or ability to extract pristine ECG features.

[Depression therapy for somatic diseases]

A review of works devoted to the problem of psychopharmacotherapy of depression in general medical practice is presented. The issues of its comorbidity with somatic and neurological diseases, as well as multimorbidity are discussed. Both direct and side-effects of antidepressants, which are important for effective therapy of not only affective disorders proper, but also the symptoms of the leading pathology, are considered in detail for individual organs and systems. The analysis of the preferred pharmacological classes of antidepressants, which are drugs of first choice, taking into account the somatic condition of the patient, is carried out, and drugs are indicated, the appointment of which is undesirable for the treatment of a patient with a certain disease. The presented results are aimed both at increasing the efficiency of therapy for patients with general medical level of health care, and at increasing the safety of treatment of psychiatric patients with concomitant somatic disorders.

Antiepileptic Drug Tiagabine Does Not Directly Target Key Cardiac Ion Channels Kv11.1, Nav1.5 and Cav1.2

Tiagabine is an antiepileptic drug used for the treatment of partial seizures in humans. Recently, this drug has been found useful in several non-epileptic conditions, including anxiety, chronic pain and sleep disorders. Since tachycardia-an impairment of cardiac rhythm due to cardiac ion channel dysfunction-is one of the most commonly reported non-neurological adverse effects of this drug, in the present paper we have undertaken pharmacological and numerical studies to assess a potential cardiovascular risk associated with the use of tiagabine. A chemical interaction of tiagabine with a model of human voltage-gated ion channels (VGICs) is described using the molecular docking method. The obtained in silico results imply that the adverse effects reported so far in the clinical cardiological of tiagabine could not be directly attributed to its interactions with VGICs. This is also confirmed by the results from the isolated organ studies (i.e., calcium entry blocking properties test) and in vivo (electrocardiogram study) assays of the present research. It was found that tachycardia and other tiagabine-induced cardiac complications are not due to a direct effect of this drug on ventricular depolarization and repolarization.

Nortriptyline serum concentration as a predictor for cardiac risk in amitriptyline-treated patients

PURPOSE

Tricyclic antidepressants have been shown to affect electrocardiogram (ECG) parameters, but there is limited evidence in relation to the serum concentrations. Therefore, we aimed to evaluate a prediction of cardiac risk in amitriptyline- and doxepin-treated patients by serum concentrations.

PATIENTS AND METHODS

The association between serum concentrations of amitriptyline (n = 100) and doxepin (n = 71) and ECG parameters was retrospectively examined using linear regression analysis. Mann-Whitney U tests were applied to evaluate differences in QTc intervals in patients with serum concentrations above and below the upper limit of the therapeutic reference range, as well as the alert level of each target drug.

RESULTS

The sum serum concentration of amitriptyline and the nortriptyline serum concentration were significantly associated with an increased PQ interval (p = 0.020, p = 0.007), as well as with increased QTcB (p = 0.012, p < 0.001) and QTcF intervals (p = 0.025, p < 0.001). The nortriptyline concentration was significantly associated with the QRS interval (p = 0.003). In patients with active moiety concentrations above the alert level (300 ng/ml) and nortriptyline concentrations above the reference range (170 ng/ml), the QTcB interval was significantly prolonged (p = 0.032, p = 0.007). No significant association with any ECG parameter was detected for doxepin serum concentrations.

CONCLUSION

The effect of amitriptyline on ECG parameters may be explained by nortriptyline alone. Accordingly, with increasing nortriptyline concentrations, the potential risk for an atrioventricular block, a bundle branch block, and prolongation of QTc interval may increase significantly.

A physiological examination of perceived incorporation during trance

Background: Numerous world cultures believe channeling provides genuine information, and channeling rituals in various forms are regularly conducted in both religious and non-religious contexts. Little is known about the physiological correlates of the subjective experience of channeling. Methods: We conducted a prospective within-subject design study with 13 healthy adult trance channels. Participants alternated between 5-minute blocks of channeling and no-channeling three times while electroencephalography (EEG), electrocardiography (ECG), galvanic skin response (GSR), and respiration were collected on two separate days. Voice recordings of the same story read in channeling and no-channeling states were also analyzed.   Results: The pre-laboratory survey data about demographics, perception of the source, purpose and utility of channeled information reflected previous reports. Most participants were aware of their experience (rather than in a full trance) and had varying levels of perceived incorporation (i.e. control of their body). Voice analysis showed an increase in voice arousal and power (dB/Hz) differences in the 125 Hz bins between 0 and 625 Hz, and 3625 and 3875 Hz when reading during the channeling state versus control. Despite subjective perceptions of distinctly different states, no substantive differences were seen in EEG frequency power, ECG measures, GSR and respiration. Conclusions: Voice parameters were different between channeling and no-channeling states using rigorous controlled methods, but other physiology measure collected were not. Considering the subjective and phenomenological differences observed, future studies should include other measures such as EEG connectivity analyses, fMRI and biomarkers.

A physiological examination of perceived incorporation during trance

Background: Numerous world cultures believe channeling provides genuine information, and channeling rituals in various forms are regularly conducted in both religious and non-religious contexts. Little is known about the physiological correlates of the subjective experience of channeling.

Methods: We conducted a prospective within-subject design study with 13 healthy adult trance channels. Participants alternated between 5-minute blocks of channeling and no-channeling three times while electroencephalography (EEG), electrocardiography (ECG), galvanic skin response (GSR), and respiration were collected on two separate days. Voice recordings of the same story read in channeling and no-channeling states were also analyzed.  

Results: The pre-laboratory survey data about demographics, perception of the source, purpose and utility of channeled information reflected previous reports. Most participants were aware of their experience (rather than in a full trance) and had varying levels of perceived incorporation (i.e. control of their body). Voice analysis showed an increase in voice arousal and power (dB/Hz) differences in the 125 Hz bins between 0 and 625 Hz, and 3625 and 3875 Hz when reading during the channeling state versus control. Despite subjective perceptions of distinctly different states, no substantive differences were seen in EEG frequency power, ECG measures, GSR and respiration.

Conclusions: Voice parameters were different between channeling and no-channeling states using rigorous controlled methods, but other physiology measure collected were not. Considering the subjective and phenomenological differences observed, future studies should include other measures such as EEG connectivity analyses, fMRI and biomarkers.

Analysis of the effect of the antidepressant sertraline on the length of QT interval in patients with depression and alcohol dependence

Introduction and Aim: Depression in psychiatry covers a large area of mental pathology and it is one of the most complex problems of modern medicine with broad implications for the health of the individual and the society as a whole. Depression is also a frequent companion of alcohol addiction. The aim of this study was to investigate the effect of the antidepressant drug sertraline on the length of QT interval in depressed patients with alcohol dependence. Patients and methods: This research included male patients (older than 18 years of age) suffering from alcohol addiction, who were also diagnosed with depression, that is, depressive disorder, at the beginning of hospitalisation, on the basis of DSM-IV (Diagnostic and statistical manual of mental disorders) criterion and positive Hamilton Rating Scale for Depression (HRSD). The study included 49 patients treated with antidepressant sertraline for 20 days. In our study, the global QTc interval (12 leads) was determined automatically by applying ECG device of the producer and type "Schiller Cardiovit AT-1", which uses "SCHILLER ECG Measurement and Interpretation Software for Children and Adult ECGs". Measured/empirical values of data were statistically processed in SPSS 16.0 programme package for Windows. Methods of descriptive statistics and methods of statistic testing of hypotheses were used. Results: In our study, in spite of the vulnerability of patients due to the heart damage and the liver dysfunction arising from alcohol consumption, as well as altered patients' drugs metabolism, no elongation of QTc interval resulting from the application of sertraline was established (p = 0.735). The average prolongation of QTc interval of 1.633 ms was observed (95% CI = 8.005 ms, 11.270 ms). Conclusion: Our study does not indicate that the antidepressant drug sertraline has a statistically significant effect on the prolongation of the QT interval of depressed patients with alcohol dependence.

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.

Heartbeat Complexity Modulation in Bipolar Disorder during Daytime and Nighttime

This study reports on the complexity modulation of heartbeat dynamics in patients affected by bipolar disorder. In particular, a multiscale entropy analysis was applied to the R-R interval series, that were derived from electrocardiographic (ECG) signals for a group of nineteen subjects comprised of eight patients and eleven healthy control subjects. They were monitored using a textile-based sensorized t-shirt during the day and overnight for a total of 47 diurnal and 27 nocturnal recordings. Patients showed three different mood states: depression, hypomania and euthymia. Results show a clear loss of complexity during depressive and hypomanic states as compared to euthymic and healthy control states. In addition, we observed that a more significant complexity modulation among healthy and pathological mood states occurs during the night. These findings suggest that bipolar disorder is associated with an enhanced sleep-related dysregulation of the Autonomic Nervous System (ANS) activity, and that heartbeat complex dynamics may serve as a viable marker of pathological conditions in mental health.

Sedation and Analgesia

Patients in the cardiothoracic intensive care unit (CTICU) are subject to numerous physical and mental stresses. While most of these cannot be completely eliminated, intensivists have many tools in their armamentarium to alleviate patients' pain and suffering. This chapter will consider the importance of analgesia and sedation in the CTICU and the relevant consequences of over- or under-treatment. We will examine the tools available for monitoring and titrating analgesia and sedation in critically ill patients. The major classes of medications available will be reviewed, with particular attention to their clinical effects, metabolism and excretion, and hemodynamic characteristics. Lastly, experimental evidence will be assessed regarding the best strategies for treatment of pain and agitation in the CTICU, including use of non-pharmacologic adjuvants.

Evaluation of the Relationship Between Pharmacokinetics and the Safety of Aripiprazole and Its Cardiovascular Effects in Healthy Volunteers

AIMS

The aim of this study was the evaluation of the possible relationship between pharmacokinetics and the safety of aripiprazole as well as its influence on blood pressure (BP), heart rate (HR), and corrected QT (QTc) interval.

METHODS

The study population comprised 157 healthy volunteers from 6 bioequivalence clinical trials. Subjects were administered a single 10-mg oral dose of each formulation separated by a 28-day washout period. Plasma concentrations were measured using high-performance liquid chromatography coupled to mass spectrometry. Blood pressure was measured at the following times: predose and 0.5, 2, 4, 6, and 8 hours postdose. An electrocardiogram was recorded at predose, 4, and 8 hours postdose.

RESULTS

Area under the curve (AUC), maximum plasma concentration, half-life, and distribution volume corrected for weight were higher in women. Aripiprazole treatment produced a decrease of BP (9.3 mm Hg on systolic and 6.2 mm Hg on diastolic pressure) and an increase in HR (12.1 beats per minute) and QTc interval (9.1 milliseconds). There were sex differences in BP, HR, and QTc interval. Women and subjects with higher AUC and maximum plasma concentration values were more prone to experience adverse drug reactions and gastrointestinal adverse reactions. The AUC was related with systolic BP and diastolic BP decrease and HR increase but there was no relationship between aripiprazole concentrations and QTc increase.

CONCLUSIONS

Aripiprazole decreases BP and increases HR and QTc interval. Pharmacokinetics, pharmacodynamics, and safety of aripiprazole are affected by sex. There is a directly proportional relationship between pharmacokinetic parameters and adverse drug reactions and effect on BP and HR.

A long-term noninterventional safety study of adjunctive lacosamide therapy in patients with epilepsy and uncontrolled partial-onset seizures

This noninterventional, observational, postauthorization safety study (SP0942, NCT00771927) evaluated the incidence of predefined cardiovascular- (CV) and psychiatric-related treatment-emergent adverse events (TEAEs), in patients with epilepsy and uncontrolled partial-onset seizures, when initiating adjunctive therapy with lacosamide or another approved antiepileptic drug (AED) according to standard medical practice. Active recording of predefined TEAEs of interest took place at three-monthly recommended visits for up to 12months. Of 1004 patients who received at least one dose of adjunctive AEDs, 511 initially added lacosamide therapy, 493 added another AED, 69 were ≥65years of age, and 72 took concomitant antiarrhythmic drugs. Patients in the lacosamide cohort had a higher median frequency of partial-onset seizures (6.0 versus 3.5 per 28days) despite taking more concomitant AEDs (84.9% versus 66.9% took ≥2) at baseline. Patients who added lacosamide took a modal dose of 200mg/day over the treatment period (n=501), and 50.1% (256/511) completed 12months of treatment. Fifty-one point nine percent (256/493) of patients who added another AED completed the study, with the most commonly added AED being levetiracetam (28.4%). Four patients (0.8%) in each cohort, all <65years of age, reported predefined CV-related TEAEs. None were considered serious or led to discontinuation. One event each of sinus bradycardia (lacosamide), atrioventricular block first degree (lacosamide), and syncope (other AED) were judged to be treatment-related. Another patient in the other AED cohort reported bradycardia while taking concomitant antiarrhythmic drugs. Predefined psychiatric-related TEAEs were reported by 21 patients (4.1%) in the lacosamide cohort and 27 patients (5.5%) in the other AED cohort. Depression was the most common to be treatment-related (7/11 and 12/18 of patients reporting treatment-related psychiatric TEAEs, respectively). Serious psychiatric-related TEAEs were reported by four patients who added lacosamide (two cases of depression, two of suicide attempt) and one who added another AED (depression). Seven deaths occurred, all of which were considered unrelated/unlikely related to study medication. This thorough evaluation revealed a low incidence of predefined CV- and psychiatric-related TEAEs in patients taking adjunctive AED therapy according to standard medical practice. No specific safety concerns related to adjunctive lacosamide therapy were noted.

Antidepressants and antipsychotics classified with torsades de pointes arrhythmia risk and mortality in older adults - a Swedish nationwide study

AIM

The aim of the study was to examine mortality risk associated with use of antidepressants and antipsychotics classified with torsades de pointes (TdP) risk in elderly.

METHODS

A matched case-control register study was conducted in people 65 years and older dying outside hospital from 2008-2013 (n = 286,092) and matched controls (n = 1,430,460). The association between prescription of antidepressants and antipsychotics with various TdP risk according to CredibleMeds (www.crediblemeds.org) and all-cause mortality was studied by multivariate conditional logistic regression adjusted for comorbidity and several other confounders.

RESULTS

Use of antidepressants classified with known or possible TdP risk, was associated with higher adjusted risk for mortality (OR 1.53, 95% CI 1.51, 1.56 and OR 1.63, 95% CI 1.61, 1.67, respectively) compared with antidepressants classified with conditional TdP risk (OR 1.25, 95% CI 1.22, 1.28) or without TdP classification (OR 0.99, 95% CI 0.94, 1.05). Antipsychotics classified with known TdP risk were associated with higher risk (OR 4.57, 95% CI 4.37, 4.78) than antipsychotics with possible risk (OR 2.58, 95% CI 2.52, 2.64) or without TdP classification (OR 2.14, 95% CI 2.03, 2.65). The following risk ranking was observed for commonly used antidepressants: mirtazapine > citalopram > sertraline > amitriptyline and for antipsychotics: haloperidol > risperidone >olanzapine > quetiapine.

CONCLUSION

The CredibleMeds system predicted drug-associated risk for mortality in the elderly at the risk class level. Among antipsychotics, haloperidol, and among antidepressants, mirtazapine and citalopram, were associated with the highest risks. The results suggest that the TdP risk with antidepressants and antipsychotics should be taken into consideration when prescribing to the elderly.

Management of psychosis and agitation in medical-surgical patients who have or are at risk for prolonged QT interval

We review the literature on management of psychosis and agitation in medical-surgical patients who have or are at risk for prolonged QT interval, a risk factor for torsade de pointes (TdP), and we describe our protocols for treating these patients. We searched PubMed and PsycInfo for relevant studies and found few papers describing options for treating psychosis and agitation in these patients. Prolonged QTc interval has been more often associated with low-potency phenothiazines such as thioridazine; however, it may occur with high potency typical antipsychotics such as fluphenazine and haloperidol as well as with atypical antipsychotics such as quetiapine, risperidone, olanzapine, iloperidone, and particularly ziprasidone. Antipsychotics for which no association with prolonged QTc interval has been shown include lurasidone, clozapine, and aripiprazole. For patients who have risk factors for prolonged QTc interval but whose electrocardiograms do not show this, reasonable first choices include oral or intramuscular olanzapine or aripiprazole, followed by risperidone and quetiapine or oral or intramuscular haloperidol. For those who have prolonged QTc but that measures less than 500 ms, we limit the use of antipsychotics to aripiprazole, olanzapine, risperidone, or quetiapine. Finally, for patients who have a QTc of 500 ms or greater, we rely on aripiprazole, valproate, trazodone, and benzodiazepines.

Sudden death in Parkinson's disease: a retrospective autopsy study

The aim of this paper is to reveal the causes of death and to verify sudden death of Parkinson's disease (PD) in an autopsy study. We reviewed the clinical data and the causes of death in 16 PD patients who had postmortem examinations. Prior to autopsy, nine patients died of known causes: five patients died of aspiration pneumonia, two of myocardial infarction, one of asphyxia, and one of dilated cardiomyopathy. Autopsy confirmed that the putative causes of death were compatible with the pathological ones. The remaining seven patients died suddenly of unknown causes. Autopsy revealed that the causes of death were asphyxia in two patients and perforation of a duodenal ulcer in one patient. Autopsy did not determine the causes of unknown death in the remaining four patients. Consequently, autopsy revealed that eight patients died of swallowing problems such as aspiration pneumonia and asphyxia, four of sudden death, three of cardiac problems, and one of a gastrointestinal problem. Although there was a bias that all patients had a postmortem examination, our study revealed that several PD patients died of sudden death without any satisfactory causes of death determined even by autopsy. Therefore, we propose that a non-negligible number of PD patients die of sudden death.

QTc prolongation with antipsychotics: is routine ECG monitoring recommended?

Whether or not QTc interval should be routinely monitored in patients receiving antipsychotics is a controversial issue, given logistic and fiscal dilemmas. There is a link between antipsychotic medications and prolongation of QTc interval, which is associated with an increased risk of torsade de pointes (TdP). Our goal is to provide clinically practical guidelines for monitoring QTc intervals in patients being treated with antipsychotics. We provide an overview of the pathophysiology of the QT interval, its relationship to TdP, and a discussion of the QT prolonging effects of antipsychotics. A literature search for articles relevant to the QTc prolonging effects of antipsychotics and TdP was conducted utilizing the databases PubMed and Embase with various combinations of search words. The overall risk of TdP and sudden death associated with antipsychotics has been observed to be low. Medications, genetics, gender, cardiovascular status, pathological conditions, and electrolyte disturbances have been found to be related to prolongation of the QTc interval. We conclude that, while electrocardiogram (ECG) monitoring is useful when administering antipsychotic medications in the presence of co-existing risk factors, it is not mandatory to perform ECG monitoring as a prerequisite in the absence of cardiac risk factors. An ECG should be performed if the initial evaluation suggests increased cardiac risk or if the antipsychotic to be prescribed has been established to have an increased risk of TdP and sudden death.

Clinical effectiveness of aripiprazole in short-term treatment of tic disorder in children and adolescents: a naturalistic study

BACKGROUND/PURPOSE

The purpose of this study was to evaluate the effectiveness and tolerability of aripiprazole in short-term treatment of children and adolescents with tic disorder (TD).

METHODS

This was a 14-week, prospective, open-label flexible dose trial of aripiprazole. We enrolled patients with TD aged between 4 years and 18 years. They received aripiprazole (dose: 2.5 mg/day) initially, which was then adjusted according to clinical response. The severity was assessed by the Yale Global Tic Severity Score (YGTSS) at 0, 2, 6, 10, and 14 weeks. The linear mixed models were used for evaluation of the YGTSSs at each follow-up, which were compared with baseline scores.

RESULTS

Eighty-one patients were enrolled in this study. Nine patients withdrew from the study with complaints of adverse side effects. Of the remaining 72 patients, 15 patients discontinued medications prematurely due to being free of symptoms for over 2 weeks. Two patients discontinued medications due to no significant improvement. The mean scores had significantly decreased since the 2nd week (p < 0.01). The mean reduction was 51.0% in the motor tic scores, 67.1% in the vocal tic scores, and 70.0% in the total YGTSSs. The common adverse effects were sedation (32.1%) and increased appetite (22.2%). A slight increase in average body weight was noted, from 32.7 to 33.7 kg (+1.0 kg, p < 0.05).

CONCLUSION

Aripiprazole is effective for short-term treatment of TD, especially vocal tics, in children and adolescents with mild adverse effects. However, further double-blind trials against placebo or other medications are needed to verify the efficacy of aripiprazole in the pharmacotherapy of TD.

Peak high-frequency HRV and peak alpha frequency higher in PTSD

Posttraumatic stress disorder (PTSD) is difficult to treat and current PTSD treatments are not effective for all people. Despite limited evidence for its efficacy, some clinicians have implemented biofeedback for PTSD treatment. As a first step in constructing an effective biofeedback treatment program, we assessed respiration, electroencephalography (EEG) and heart rate variability (HRV) as potential biofeedback parameters for a future clinical trial. This cross-sectional study included 86 veterans; 59 with and 27 without PTSD. Data were collected on EEG measures, HRV, and respiration rate during an attentive resting state. Measures were analyzed to assess sensitivity to PTSD status and the relationship to PTSD symptoms. Peak alpha frequency was higher in the PTSD group (F(1,84) = 6.14, p = 0.01). Peak high-frequency HRV was lower in the PTSD group (F(2,78) = 26.5, p < 0.00005) when adjusting for respiration rate. All other EEG and HRV measures and respiration were not different between groups. Peak high-frequency HRV and peak alpha frequency are sensitive to PTSD status and may be potential biofeedback parameters for future PTSD clinical trials.

Aging and Clinical Pharmacology: Implications for Antidepressants

The elderly frequently have changes in pharmacokinetics, sensitivity to medications, homeostatic reserve (ability to tolerate physiological challenges), exposure to multiple medications, and adherence. All of these age-associated factors can potentially influence total exposure to medication, adverse effects, and subsequent treatment outcome. Most clinical trials are performed with healthy, younger adults. Extrapolating the results of these trials to the elderly may be inappropriate, particularly for the antidepressant treatment of depression. The authors review these age-associated differences and discuss their implications for antidepressant use in older adults.

Clinical use of antidepressant therapy and associated cardiovascular risk

A number of different psychotropic agents have been associated with an increased risk of cardiovascular disease, and these relationships have been difficult to interpret due to the presence of confounding factors. Recently, there has been renewed interest in the potential for certain antidepressants to cause QT prolongation, which is a predisposing factor for arrhythmia. However, the optimum means of determining QT remains contentious due to discrepancies between methods that may be readily applied in a clinical setting versus more detailed techniques during regulatory assessment. A number of different pharmacological mechanisms might explain the occurrence of adverse cardiac effects, and these differ according to the type of antidepressant agent. Emerging data indicate that citalopram exhibits a dose-effect relationship for QT prolongation. Whereas cardiotoxicity is readily apparent in the context of intentional antidepressant overdose, the occurrence of cardiac effects as a result of therapeutic administration is less certain. Pre-existing cardiac disease and other factors that independently predispose to arrhythmia are important considerations. Therefore, clinical judgment is needed to evaluate the overall risk or benefit of a particular antidepressant in any patient. Close monitoring should be considered for those at greatest risk of QT prolongation and arrhythmia.

Overdose of atypical antipsychotics: clinical presentation, mechanisms of toxicity and management

Historically, treatment for schizophrenia focused on sedation. The advent of the typical antipsychotics resulted in treatment aimed specifically at the underlying disease, but these agents were associated with numerous adverse effects, and were not particularly effective at treatment of the negative symptoms of schizophrenia. As a result, numerous atypical agents have been developed over the past 2 decades, including several agents within the past 5 years. Overdose of antipsychotics remains quite common in Western society. In 2010, poison control centres in the US received nearly 43,000 calls related to atypical antipsychotics alone. Due to underreporting, the true incidence of overdose with atypical antipsychotics is likely much greater. Following overdose of an atypical antipsychotic, the clinical effects observed, such as CNS depression, tachycardia and orthostasis are largely predictable based on the unique receptor binding profile of the agent. This article, which focuses on the atypical antipsychotics commonly used in the treatment of schizophrenia, discusses the features commonly encountered in overdose. Specifically, agents that result in QT prolongation and the corresponding potential for torsades de pointes, as well as unique features encountered with the various medications are discussed. The diagnosis of this overdose is largely based on history. Routine use of drug screens is unlikely to be beneficial. The primary goal of management is aggressive supportive care. Patients with significant CNS depression with associated loss of airway reflexes and respiratory failure need advanced airway management. Hypotension should be treated first with intravenous fluids, with the use of direct acting vasopressors reserved for persistent hypotension. Benzodiazepines should be used for seizures, with barbiturates used for refractory seizures. Intravenous magnesium can be administered for patients with a corrected QT interval exceeding 500 milliseconds.

QTc prolongation by psychotropic drugs and the risk of Torsade de Pointes

INTRODUCTION

Many psychotropic drugs can delay cardiac repolarization and thereby prolong the rate-corrected QT interval (QTc). A prolonged QTc often arouses concern in clinical practice, as it can be followed, in rare cases, by the life-threatening polymorphic ventricular tachyarrhythmia called torsade de pointes (TdP).

METHOD

We searched PubMed for pertinent literature on the risk of QTc prolongation and/or TdP associated with commonly used psychotropic drugs.

RESULTS

Thioridazine and ziprasidone confer the highest risk of QTc prolongation and/or TdP. There is also a clinically significant risk associated with haloperidol given intravenously in high doses. TdP has been reported in a few cases in association with the use of newer antipsychotic drugs (mainly quetiapine and amisulpride), most of the tri- and tetracyclic antidepressants, and the selective monoamine reuptake inhibitors citalopram, fluoxetine, paroxetine, and venlafaxine. As a rule, however, QTc prolongation and/or TdP occur only in the presence of multiple additional risk factors, such as age over 65 years, pre-existing cardiovascular disease, bradycardia, female sex, hypokalemia, hypomagnesemia, a supratherapeutic or toxic serum concentration, or the simultaneous administration of other drugs that delay repolarization or interfere with drug metabolism.

CONCLUSION

Before prescribing a psychotropic drug, the physician should carefully assess its risks and benefits to avoid this type of adverse reaction, particularly when additional risk factors are present. The ECG and electrolytes should be regularly monitored in patients taking psychotropic drugs.

Antidepressants and the risk of sudden cardiac death and ventricular arrhythmia

PURPOSE

To examine the association between exposure to antidepressants and emergency department or inpatient admission for sudden cardiac death and ventricular arrhythmia (SD/VA), and to examine the impact of dose and cytochrome P-450 inhibition.

METHODS

A cohort study was conducted using 1999-2003 Medicaid claims data from beneficiaries of five large states, supplemented with Medicare claims for dually eligible individuals. Exposures were prescription claims for antidepressants of interest or a reference antidepressant. Outcomes were incident first-listed emergency department or principal inpatient diagnoses indicative of SD/VA originating in the outpatient setting, an outcome previously found to have a positive predictive value of 85%.

RESULTS

In 1.3 million person-years of antidepressant exposure, we identified 4222 SD/VA outcomes for a rate of 3.3/1000 person-years (95%CI, 3.2-3.4). Compared with paroxetine (a referent with a putatively favorable cardiovascular risk profile), adjusted hazard ratios (HRs) were 0.80 (0.67-0.95) for bupropion, 1.24 (0.93-1.65) for doxepin, 0.79 (0.55-1.15) for lithium, and 1.26 (1.11-1.42) for mirtazapine. HRs for amitriptyline, citalopram, fluoxetine, nefazodone, nortriptyline, sertraline, trazodone, and venlafaxine were near unity. For antidepressants having nonnull risks (bupropion and mirtazapine), we observed no relationship with antidepressant dose and some relationships with concomitant cytochrome P-450 inhibition.

CONCLUSIONS

Of antidepressants studied, only mirtazapine had a statistically significantly greater SD/VA risk versus paroxetine. However, baseline differences between these users suggest that this finding may be attributable to residual confounding. Eleven other antidepressants had SD/VA risks no greater than that of paroxetine, thereby providing reassurance regarding the comparative cardiovascular safety of antidepressants.

Adjunctive benzodiazepine treatment of hospitalized schizophrenia patients in Asia from 2001 to 2008

Benzodiazepines are commonly prescribed to patients with schizophrenia in many countries, but as little is known about such treatment in Asia, we evaluated their adjunctive use for 6761 in-patients diagnosed with schizophrenia in nine Asian countries using a cross-sectional study design in 2001, 2004 and 2008. Multivariate logistic regression and multivariate linear regression analyses were performed to assess predictors of benzodiazepine use and dose, respectively. Overall, 54% of the patients received adjunctive benzodiazepines at an average daily dose equivalent to 30.3 mg diazepam, with minor changes over the years sampled. Benzodiazepine use was highest in Taiwan and Japan, lowest in Thailand and China, and was associated with fewer years ill, presence of delusions (OR 1.24), hallucinations (OR 1.22), disorganized speech (OR 1.17), social or occupational dysfunction (OR 1.16), and use of mood stabilizers (OR 3.15), antiparkinsonian (OR 1.79) or antidepressant drugs (OR 1.33), and lower doses of antipsychotics (all p=0.016 to <0.001). Benzodiazepine doses were highest in Taiwan and China, lowest in Korea and Singapore; higher doses were associated with being young, male, physically aggressive, receiving mood stabilizers, and having electroconvulsive treatment (all p=0.019 to <0.001). Benzodiazepine use was associated with neurological and systemic adverse effects. In conclusion, benzodiazepine use was common in Asian patients with schizophrenia. Predictors of benzodiazepine use and dose differed in this population. Critical clinical guidelines should be developed specifically for Asian countries to address sound practices in regard to use of benzodiazepines for psychotic disorders.

Effects on prolongation of Bazett's corrected QT interval of seven second-generation antipsychotics in the treatment of schizophrenia: a meta-analysis

The use of second-generation antipsychotics (SGAs) for the treatment of schizophrenia has surged worldwide. Amisulpride, aripiprazole, olanzapine, quetiapine, risperidone, sertindole and ziprasidone have now been commonly prescribed. Their effects on QT interval differ but evidence remains sparse and mostly inconclusive. Since prolongation of heart-rate corrected QT interval has been implicated as an useful surrogate marker to predict drug-related cardiac mortality and pro-arrhythmic potentials, it is timely and necessary to compare the effects of Bazett's corrected QT interval (QT(Bc)) prolongation for the commonly prescribed SGAs. A meta-analysis was conducted according to suggestions by the Quality of Reporting of Meta-analysis group with literature identified using various databases and augmented with hand-searching to assess the magnitude and risk on QT(Bc) prolongation by these seven SGAs for treatments in adult subjects with schizophrenia. Because of incomplete QT(Bc) data reporting, quetiapine could not be assessed by the meta-analytical approach in this study. Aripiprazole was the only SGA associated with both statistically significant lower risk and mean change in QT(Bc), with sertindole giving a statistically significant worsening effect on mean QT(Bc). Other analyses did not demonstrate any statistically significant pooled effects for the studied SGAs, neither on the magnitude over mean or mean change, nor the risk on QT(Bc) prolongation.

A bizarre electrocardiographic pattern due to chronic lithium therapy

Cardiotoxicity that results from lithium overdose is uncommon and electrocardiographic (ECG) changes are rarely reported. However, some authors have specifically reported the occurrence of ischemic ECG changes due to a lithium overdose. This article describes a case that is demonstrating ECG changes that mimic inferior myocardial infarction during the course of chronic lithium treatment and showing QTc prolongation in this patient. The patients' ECG changes were partially recovered after hemodialysis.

Effectiveness and tolerability of aripiprazole in children and adolescents with Tourette's disorder: a pilot study in China

OBJECTIVE

The primary aim of the study was to evaluate the effectiveness and tolerability of aripiprazole on motor and vocal tics in children and adolescents with Tourette's disorder (TD). The secondary aim was to assess the response of TD-associated behaviors to aripiprazole exposure.

METHODS

This was an 8-week, open-label trial with flexible dosing strategy of aripiprazole in children and adolescents with TD. A total of 72 patients, aged 6-18 years, participated in the 8-week trial. The Yale Global Tic Severity Scale (YGTSS), the Clinical Global Impressions-Tics (CGI-Tics), and the Child Behavior Checklist (CBCL) were compared at the baseline, weeks 2 and 4, and end point. The side effects of aripiprazole, electrocardiogram (ECG), and body mass index (BMI) were evaluated.

RESULTS

Over the 8-week trial, aripiprazole administration was associated with a significant decrease in total tic severity as measured by the YGTSS (50.3% reduction by week 8). The mean scores of motor tic in the YGTSS were 17.42 +/- 4.83, 12.93 +/- 3.76, 8.39 +/- 3.70, and 6.75 +/- 3.95 at baseline, weeks 2 and 4, and end point. A significant decrease in the scores was observed in week 2 compared to the baseline, and the scores continued to decrease for the remainder of the study period (degrees of freedom [df ] = 3, F = 96.02, p = 0.000). The mean phonic tic scores were 12.71 +/- 4.60, 8.53 +/- 3.26, 6.10 +/- 2.50, and 3.63 +/- 2.20 at baseline, weeks 2 and 4, and end point, respectively. A significant change was observed during week 2 compared to the baseline, and this change continued for the rest of the study period (df = 3, F = 95.16, p = 0.000). Significant improvement was also observed according to the CGI-Tics severity. The mean CGI-Tics severity score was 4.77 +/- 1.69 at baseline and decreased to 2.20 +/- 1.39 at end point (t = 10.70, p = 0.000). A significant reduction of behavior symptoms was noticed according to the CBCL and its subscales between baseline and end point. The majority of subjects tolerated aripiprazole well. The extrapyramidal symptoms (EPS) during this study were negligible. In all 21 (29.2%) of the 72 participants complained of nausea and 19 (26.4%) of them reported sedation. There was no significant difference of BMI between the two phases (df = 64, t = -0.94, p = 0.352). There were no significant changes in laboratory results. ECG monitoring revealed no significant impact on cardiac conduction by aripiprazol.

CONCLUSION

In this preliminary open-label trial, aripiprazole showed effectiveness in treating tic symptoms without causing significant weight gain or other serious side effects. Aripiprazole could be an option for TD cases that do not respond to conventional therapies. Further controlled, double-blind studies are warranted.

Impact and clinical management of depression in patients with coronary artery disease

The rates of major adverse coronary events, including recurrent ischemic events and death, in patients with coronary artery disease (CAD) have been shown to be significantly increased in patients with depression. In addition, health care costs are higher and health-related quality of life is lower in depressed patients with CAD. Several pathophysiologic mechanisms have been proposed for the association of increased events seen in this population. Studies have focused on antidepressants (specifically, selective serotonin reuptake inhibitors and mirtazapine), psychotherapy (cognitive behavioral therapy and interpersonal psychotherapy), and a wide range of other nonpharmacologic interventions. Pharmacologic and nonpharmacologic treatments are known to improve depressive symptoms in patients with CAD, but their effects on outcomes such as mortality and hospital admissions remain controversial. If treatment of depression is warranted, strategies should include sertraline or citalopram, with or without cognitive behavioral therapy, based on the known efficacy and safety of the drugs in this population. Nonpharmacologic therapy such as aerobic exercise has been shown to improve not only depression but also cardiovascular health. When selecting an appropriate antidepressant, clinicians should consider their patients' comorbid conditions and the potential for drug interactions, and treatment should be frequently monitored. Screening for depression in patients with cardiac disease should be instituted on a routine basis by using either case-finding or symptom-triggered approaches. Based on the high prevalence of depression and its known adverse effects in patients with CAD, future research is needed to help determine the role of antidepressants and nonpharmacologic strategies in improving outcomes in patients with both comorbidities.

Apparent desensitization of the effects of sigma receptor ligand haloperidol in isolated rat and guinea pig hearts after chronic treatment

The supposed role of cardiac sigma receptors is fine tuning of contractility. Sigma receptors affect several ionic channels and hence their signaling is reflected by the electrophysiological properties of the heart. Numerous ligands of sigma receptors are known to prolong the QT interval and therefore cause a variety of arrhythmias, including severe ones. The effects of the prototypical sigma ligand haloperidol have been studied extensively in humans as well as in various animal models, primarily after acute administration. We examined the incidence of arrhythmias, changes in heart rate, and prolongation of QT interval in isolated Langendorff-perfused rat and guinea pig hearts after they were exposed to nanomolar concentrations of haloperidol. Hearts from both untreated (acute) and pretreated (chronic) animals were investigated. While QT prolongation and arrhythmias due to haloperidol administration were observed in untreated rat and guinea pig hearts, arrhythmias were completely prevented in both species of chronically treated animals. In treated guinea pigs, the results were generally less convincing. Since the hearts were exposed to nanomolar concentration of haloperidol, we conclude that our data may be explained by desensitization of sigma receptors.

Electrophysiological changes of cardiac function during antidepressant treatment

Some antidepressant agents can cause electrophysiological changes of cardiac function leading to ventricular arrhythmias and sudden death. However, antidepressants have also protective effects on the heart through their capacity to modulate cardiac autonomic-mediated physiological responses. Heart rate variability and QTc length are two strictly linked parameters that allow us to appreciate the effects of different drugs on cardiac physiology. Heart rate variability reflects functioning of the autonomic nervous system and possibly also regulation by the limbic system. Autonomic regulation of cardiac activity influences also cardiac repolarization and QT length, both directly and via its effects on heart rate. In this review we present the methodologies adopted to study the effect of antidepressant drugs on QT length and heart rate variability and we summarize data on electrophysiological changes related to antidepressant treatment. Clinical implications for the choice of different antidepressants in different clinical populations are discussed.

Corrected QT interval prolongation after an overdose of escitalopram, morphine, oxycodone, zopiclone and benzodiazepines

Escitalopram is the recently marketed S-enantiomer of the widely used antidepressant citalopram. Data from intentional overexposure to this medication are limited. Twelve-lead electrocardiogram (ECG) effects from racemic citalopram have been described; however, the present report is the first, to the best of the authors' knowledge, that describes all the reported abnormalities in a single patient receiving escitalopram. A 52-year-old man with a history of depression treated with escitalopram 10 mg/day, extended-release morphine 30 mg/day and zopiclone 15 mg/day was found unconscious at his home. He was known to have attempted suicide three weeks previously. Partially emptied bottles of escitalopram, morphine, oxycodone, zopiclone, lorazepam and diazepam were found close to the patient. He was transferred to the emergency department, where airway management and other supportive care were initiated. The patient was transferred to the intensive care unit. The initial 12-lead ECG demonstrated junctional rhythm at 48 beats/min, a wide complex escape (145 ms) with right bundle branch morphology and a prolonged corrected QT interval at 650 ms. Cardiac monitoring was undertaken. No ventricular arrhythmias or torsade de pointes were detected. No specific treatment for shortening the QT was implemented. Another 12-lead ECG performed 48 h later demonstrated sinus tachycardia with a normal corrected QT, normal PR interval and normal QRS duration. The effects of the overdose of escitalopram on the ECG and its interactions with other drugs are reviewed.

Pharmacological interventions for clozapine-induced hypersalivation

BACKGROUND

Clozapine is widely used for people with schizophrenia. Although agranulocytosis, weight gain, and cardiac problems are serious problems associated with its use, hypersalivation, sometimes of a gross and socially unacceptable quantity, is also common (30-80%).

OBJECTIVES

To determine the clinical effects of pharmacological interventions for clozapine-induced hypersalivation.

SEARCH STRATEGY

We searched the Cochrane Schizophrenia Group Trials Register (March 2007), inspected references of all identified studies for further trials, contacted relevant pharmaceutical companies, drug approval agencies and authors of trials.

SELECTION CRITERIA

We included randomised controlled trials comparing pharmacological interventions, at any dose and by any route of administration, for clozapine-induced hypersalivation.

DATA COLLECTION AND ANALYSIS

We extracted data independently. For dichotomous data (homogenous) we calculated relative risk (RR) with 95% confidence intervals (CI) and numbers needed to treat (NNT) on an intention-to-treat basis. We calculated weighted mean difference (WMD) for continuous data.

MAIN RESULTS

Of the 15 trials identified, 14 were conducted in China and 14 in hospitals. The quality of reporting was poor with no studies clearly describing allocation concealment and much data were missing or unusable. All results are vulnerable to considerable bias. Most frequently the primary outcome was the diameter of the wet patch on the pillow. Antimuscarinics (astemizole, diphenhydramine, propantheline, doxepin) were the most commonly evaluated drugs. For the outcome of 'no clinically important improvement' astemizole and diphenhydramine were more effective than placebo (astemizole: n=97, 2 RCTs, RR 0.61 CI 0.47 to 0.81 NNT 3 CI 2 to 5; diphenhydramine: n=131, 2 RCTs, RR 0.43 CI 0.31 to 0.58, NNT 2 CI 1.5 to 2.5), but the doses of astemizole used were those that can cause toxicity. Data involving propantheline were heterogeneous (I2= 86.6%), but both studies showed benefit over placebo. Adverse effects were poorly recorded. Of the other interventions, oryzanol (rice bran oil and rice embryo oil extract) showed benefit over the antimuscarinic doxepin in terms of 'no clinically important change' (n=104, 1 RCT, RR 0.45 CI 0.27 to 0.75, NNT 4 CI 2 to 7). The Chinese medicine suo quo wan (comprises spicebush root, Chinese yam and bitter cardamom) showed benefit over doxepin (n=70, 1 RCT, RR 'no clinically important change' 0.31 CI 0.16 to 0.59, NNT 3 CI 1.5 to 3.7).

AUTHORS' CONCLUSIONS

There are currently insufficient data to confidently inform clinical practice. The limitations of these studies are plentiful and the risk of bias is high. These trials, however, are invaluable guides for current and future study design. Well conducted randomised trials are possible. Some may be underway. Current practice outside of well designed randomised trials should be clearly justified.

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.