Clinical relevance and management of drug-related QT interval prolongation

The Effects of Moxifloxacin and Gemifloxacin on the ECG Morphology in Healthy Volunteers: A Phase 1 Randomized Clinical Trial

Moxifloxacin and gemifloxacin are the two newer broad-spectrum 8-methoxy-quinolone derivatives that are used to treat various bacterial infections in cardiac patients. In this research study, we assessed the impact of moxifloxacin and gemifloxacin on the QT intervals of electrocardiograms in normal adult doses and draw a comparison, in a controlled environment, on healthy volunteers. Additionally, the effect of both test drugs on the QRS complex was checked. Sixty healthy volunteers were randomly assigned to two groups via R-software, and each respectively received moxifloxacin and gemifloxacin for five days. The research ethics committee approved the research, and it was registered for clinical trial under NCT04692623. The participants' electrocardiograms were obtained before the start of the dose (baseline) and on the fifth day. Significant prolongation of QT interval was noted in moxifloxacin (p < 0.0001) as compared to gemifloxacin treated groups. There were no cases of QTc prolongation over the usual limits (450-470 ms) in the gemifloxacin-treated group, however, QTc prolongations at the rate of 30 and 60 ms from the baseline were noted, interpreted as per the EMEA guidelines. These findings indicate that moxifloxacin caused significant (p < 0.0001) QT interval prolongation (QTIP) as compared to gemifloxacin. In contrast to the previously reported literature, the prominent effect of moxifloxacin on the widening of the QRS-complex was noted with no such effect on QRS-widening in the gemifloxacin-treated group. It is concluded that both drugs have the potential for considerable QT interval prolongation (QTIP) effects, which is one of the risk factors for developing torsade de pointes (TdPs) in cardiac patients. Thus, clinicians should exercise caution when prescribing moxifloxacin and gemifloxacin to cardiac patients and should consider alternate treatment options.

Fatal arrhythmia following ingestion of hawthorn root (Crataegus pubescens) extract: a case report

The use of extracts from the hawthorn plant as cardiovascular agents dates back to the 1st century; recently, they have also been made available online as weight loss aids. Herein, we present a case of intentional intoxication with hawthorn root extract (HRE) in an adult patient that resulted in death. A 20-year-old female patient, who was clinically diagnosed with depression, developed hypotension, bradycardia, and depressed consciousness after ingestion of this extract. An electrocardiogram recorded a sinus arrest with a slow nodal rhythm, which rapidly deteriorated, leading to cardiac arrest. This case report illustrates the potentially fatal consequences of HRE for which the constituents have not yet been characterized. All physicians, especially those in the emergency department, should be aware of the dangerous, even potentially fatal interactions of HRE with prescription medications.

Population pharmacokinetics of oral levofloxacin in healthy volunteers and dosing optimization for multidrug-resistant tuberculosis therapy

Levofloxacin is considered a key component of a multidrug-resistant tuberculosis (MDR-TB) regimen. However, there is considerable concern regarding the subtherapeutic concentrations of the currently used doses and the development of drug resistance. Therefore, this study aimed to describe the population pharmacokinetics (PPK) of oral levofloxacin in healthy volunteers and to evaluate the probability of target attainment (PTA) in an attempt to optimize the dosing regimens for MDR-TB therapy. Data of levofloxacin in healthy volunteers from a previous study were used to construct a PPK model. Monte Carlo simulations were performed to derive the PTAs of various regimens. A two-compartment model with linear elimination and transit absorption compartments best described the pharmacokinetics (PK) of levofloxacin. The estimated PK parameters (interindividual variability, %) were: apparent clearance 8.32 L h^-1 (22.6%), apparent central volume of distribution 35.8 L (45.2%), apparent peripheral volume of distribution 39.7 L, intercompartmental clearance 40.6 L h^-1 (43.8%), absorption rate constant 7.45 h^-1 (150%), mean absorption transit time 0.355 h (52.4%), and total number of transit compartments 6.01 (131.9%). Monte Carlo simulations using levofloxacin 750-1000 mg yielded a probability of achieving a target free area under the concentration-time curve/minimum inhibitory concentration (MIC) of 100 at greater than 90% for Mycobacterium tuberculosis with an MIC < 0.5 mg L^-1 , while a dose of 1500 mg was required for strains with an MIC of 1 mg L^-1 . A higher dose of levofloxacin might be needed to treat tuberculosis. However, further studies on the efficacy and safety of this dose are needed to confirm our findings.

Amiodarone: A Comprehensive Guide for Clinicians

Amiodarone is an effective antiarrhythmic medication frequently used in practice for both ventricular and atrial arrhythmias. Though classified as a class III antiarrhythmic, it affects all phases of the cardiac action potential. However, the drug has several side effects, including thyroid abnormalities, pulmonary fibrosis, and transaminitis, for which routine monitoring is recommended. It also interacts with several medications, such as warfarin, simvastatin, and atorvastatin, and many HIV antiretroviral medications. Given the common use of this medication in medical practice, it is vital that clinicians understand the indications, contraindications, dosing, side effects, and interactions of this medication. A thorough understanding of these topics is essential for clinicians to ensure safe and effective use of amiodarone.

Changes to the electrocardiogram during exercise in anorexia nervosa

BACKGROUND

Anorexia Nervosa (AN) is an eating disorder characterized by low body weight, distorted body image, and an intense fear of gaining weight. Electrocardiogram (ECG) changes, particularly in the QT interval, have been implicated in AN-associated sudden death but not well defined.

OBJECTIVES

To characterize QT interval changes during exercise in anorexia nervosa.

METHODS

The QT interval was evaluated in a prospective cohort undergoing structured exercise. Patients from the St. Paul's Hospital Provincial Adult Tertiary Eating Disorders Program underwent a 6-minute modified exercise test protocol. A single lead ECG patch recording device was used to record a Lead I equivalent, due to challenges applying standard ECG monitoring in subjects with low body mass. Heart rate (HR) and QT interval were assessed.

RESULTS

Eighteen eating disorder patients (16 female) completed testing (age 31 ± 12 years, BMI 16.5 ± 3.8 kg/m²). Patients were compared to age- and sex-matched healthy controls. HR was similar between patients and controls (baseline: 65 (55-70)bpm vs. 69 (53-73)bpm, p = 0.83; maximum: 110 (94-139) bpm vs. 108 (93-141) bpm, p = 0.96; end recovery: 62 (54-68) bpm vs. 66 (55-75) bpm, p = 0.39). QTc intervals were similar between groups at baseline (381 ± 17 ms vs. 381 ± 46 ms, p = 0.93) and end recovery (397 ± 42 ms vs 398 ± 42 ms, p = 0.91). However, AN patients demonstrated QTc prolongation while controls showed QTc shortening at maximum HR (426 ± 70 ms vs. 345 ± 59 ms, p = 0.001).

CONCLUSION

Low level exercise HR increases are similar between AN patients and controls, but the QTc interval fails to shorten, which may explain the increased arrhythmic risk in AN.

An Observational Study of QTc Prolongation in Critically Ill Patients: Identification of Incidence and Predictors

AIMS

Despite the importance of abnormal QTc interval values in intensive care unit (ICU) patients, there is a paucity of information on this topic. The current study was designed to identify the incidence and predictors of QTc prolongation in medical (M), surgical (S), and emergency (E) ICUs.

MATERIALS AND METHODS

A prospective observational study was conducted for 6 months. Patients more than 18 years old who admitted to MICU, SICU, and EICU were included in the study. Electrocardiogram (ECG) was taken on day 1, 3, and 5 of ICU admission. The QTc intervals >460 ms in male and >470 ms in female and increased >60 ms above baseline were considered QTc prolongation. Comparative analysis was done between two groups of patients (normal vs prolonged QTc). Logistic regression models were carried out to determine the predictors of QTc prolongation.

RESULTS

Incidence of QTc prolongation was 6.5, 9.8, and 15.7% on day 1, 3, and 5 of ICU admission, respectively. On day 1, the history of alcohol addiction and the reason of ICU admission were associated with a prolonged QTc. A significant association was demonstrated between administration of azithromycin and QTc prolongation on day 3. High serum creatinine and hospitalization in EICU were predictors of QTc prolongation on day 5 of ICU admission.

CONCLUSION

The QTc prolongation is relatively common among patients admitted to ICUs and its incidence increases with increasing length of hospital stay. Predictors of QTc prolongation may be affected by the duration of ICU admission. Physicians should consider these predictors particularly before prescribing QTc-prolonging drugs.

HOW TO CITE THIS ARTICLE

Farzanegan B, Hosseinpoor Z, Baniasadi S, Seyyedi SR, Rajabi M. An Observational Study of QTc Prolongation in Critically Ill Patients: Identification of Incidence and Predictors. Indian J Crit Care Med 2020;24(4):270-275.

Drug interactions and creatinine levels are associated with QTc prolongation in intensive care units: a prospective, observational study

Background Prolongation of the QTc interval may lead to life threatening arrhythmias. QTc prolongation is common in intensive care unit (ICU) patients. The objectives of this study were to identify the role of drug-drug interactions (DDIs) and other predictors (age, sex, cardiovascular diseases, and electrolyte abnormalities) in life threatening QTc prolongation in patients admitted to medical (M), surgical (S) and emergency (E) ICUs. Methods This prospective, observational study included patients above the age of 18 years who were admitted to SICU, EICU, and MICU at a tertiary respiratory referral center. Electrocardiogram (ECG) monitoring was performed during the first 5 days of ICU admission. Risk factors and DDIs which were anticipated to be associated with the prolongation of the QTc interval were assessed for all patients. Results Two hundred patients were included in the study. QTc prolongation occurred in 10.7% of patients and the majority of patients presenting with QTc prolongation had creatinine levels above 1.3 mg/dL during their 5 days of ICU admission. Incidence of pharmacodynamic (PD) DDIs was significantly higher in patients with QTc prolongation vs. other patients. Creatinine levels above 1.3 mg/dL and PD DDIs were associated with QTc prolongation during 5 days of ICU admission. Conclusions High serum creatinine and PD DDIs can increase the risk of QTc prolongation in patients admitted to the ICU. QTc interval measurements should be performed prior to initiation or after starting any drug that is associated with QT prolongation, specifically in patients with the known risk factors.

Evaluation of the Tp-Te interval, Tp-Te/QTc ratio, and QT dispersion in patients with Turner syndrome

Objective:

To evaluate ventricular repolarization parameters using the interval from the peak to the end of the T wave (Tp–Te), together with QT and corrected QT (QTc) intervals, QT dispersion (QTd), and Tp-Te/QTc ratio in patients with Turner syndrome (pwTS) and to compare the results with those from healthy controls.

Methods:

In total, 38 patients previously diagnosed with Turner syndrome (TS) and 35 healthy girls (controls) were included in our cross-sectional study. Twelve-lead electrocardiography (ECG) and echocardiography after a 30-min rest were performed. The QT, QTc, QTd, Tp-Te interval, and Tp-Te/QTc ratio were determined.

Results:

No differences in age or sex were observed between the groups. QT intervals were similar in both groups [pwTS: 354.76±25.33 ms, controls (C): 353.29±17.51 ms, p=0.775]. pwTS had significantly longer QTc and QTd than controls (411.87±22.66 ms vs. 392.06±13.21 ms, p<0.001 and 40.31±2.02 ms vs. 37.54±1.83 ms, p<0.001, respectively). Similarly, the Tp-Te interval and Tp-Te/QTc ratio were significantly longer in pwTS than in controls (71.89±3.39 ms vs. 65.34±2.88 ms, p<0.001 and 0.17±0.01 vs. 0.16±0.01, p=0.01).

Conclusion:

As pwTS have longer QTc, QTd, Tp–Te interval, and Tp-Te/QTc ratio, an annual follow-up with ECG can provide awareness and even prevent sudden death in them. Also avoiding the use of drugs that makes repolarization anomaly and having knowledge about the side effects of these drugs are essential in pwTS.

Removal of hERG potassium channel affinity through introduction of an oxygen atom: Molecular insights from structure-activity relationships of strychnine and its analogs

Nux vomica has been effectively used in Traditional Chinese Medicine. The processing of Nux vomica is necessary to reduce toxicity before it can be used in clinical practice. However, the mechanism for processing detoxification is unclear. hERG channels have been subjected to a routine test for compound cardiac toxicity in the drug development process. Therefore, we examined the effects and mechanisms of strychnine and brucine, two main ingredients of Nux vomica, and their N-oxides on hERG channels. Strychnine and brucine exhibited concentration-dependent inhibition of hERG channels with IC₅₀ values of 25.9 μM and 44.18 μM, respectively. However, their nitrogen oxidative derivatives produced by processing of Nux vomica, strychnine N-oxide and brucine N-oxide, lost their activity on hERG channels. Compared to their parent compounds, only an oxygen atom was introduced in the nitrogen oxidative isoforms to compensate for the N⁺ - charge, suggesting that the protonated nitrogen is the key group for strychnine and brucine binding to hERG channel. Alanine-mutagenesis identified Y652 is the most important residue for strychnine and brucine binding to hERG channel. Y652A mutation increased the IC₅₀ for strychnine and brucine by 21.64-fold and 29.78-fold that of WT I_hERG, respectively. Docking simulations suggested that the protonated nitrogen of strychnine and brucine formed a cation-π interaction with the aromatic ring of Y652. This study suggests that introduction of an oxygen to compensate for the N⁺ - charge could be a useful strategy for reducing hERG potency and increasing the safety margin of alkaloid-type compounds in drug development.

Moxifloxacin-induced QT interval prolongation and torsades de pointes: a narrative review

INTRODUCTION

Moxifloxacin is widely used for the treatment of a number of infectious diseases because of its favorable pharmacological profile and high clinical success rate. However, it is often criticized for its higher risk of QTc interval prolongation (QTIP) and torsades de pointes (TdP).

AREAS COVERED

A review of published literature on moxifloxacin-related QTIP and TdP. Readers will be provided with a comprehensive overview of the prevalence, cellular mechanism, risk factors, and magnitude of QTIP of moxifloxacin.

EXPERT OPINION

In healthy subjects, moxifloxacin prolongs the QTc interval by 11.5-19.5 ms, it binds at the Tyr652 residue in the S6 pore domain of the human ether a-go-go gene related potassium channel. Considerable QTIP (30-60 ms) have also been reported in some patients, for instance the incidence of QTIP (30-60 ms) in elderly pneumonia patients was 15.5%. Moxifloxacin-induced QTIP may be of little clinical importance in healthy individuals. However, marked QTIP (>60 ms) and TdP have been reported in high-risk patients (patients who have multiple QT prolonging risk factors). Patients must be thoroughly assessed prior to the use of moxifloxacin and high-risk patients must be identified using risk assessment tools to ensure safe use of moxifloxacin and to safeguard patients' health.

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.

Detecting and Managing Adverse Effects of Antipsychotic Medications: Current State of Play

Antipsychotics are some of the most frequently prescribed medications not only for psychotic disorders and symptoms but also for a wide range of on-label and off-label indications. Because second-generation antipsychotics have largely replaced first-generation antipsychotics as first-line options due to their substantially decreased risk of extrapyramidal side effects, attention has shifted to other clinically concerning adverse events associated with antipsychotic therapy. The focus of this article is to update the nonextrapyramidal side effects associated with second-generation antipsychotics. Issues surrounding diagnosis and monitoring as well as clinical management are addressed.

Diphenhydramine and QT prolongation - A rare cardiac side effect of a drug used in common practice

There have been few cases in recent times where QT interval prolongation has been studied with regards to the use of diphenhydramine. We present a case of a patient who presented because of shortness of breath and needed emergent hemodialysis; during the course of which he developed prolonged QT interval on electrocardiography, which was correlated interestingly with the use of diphenhydramine. Pruritus is a common symptom experienced by dialysis patients. A less known, but rare side effect of diphenhydramine is prolongation of QT interval. The histamine H1 receptor antagonist diphenhydramine inhibits the fast sodium channels and at higher concentrations inhibits the repolarizing potassium channels which leads to prolongation of the action potential and the QT interval. Diphenhydramine toxicity is dose-dependent with a critical dose limit of 1.0 g. Although a lot is known about the potential side effects of antihistamines, only a few cases have cited the cardiac side effects. Thus, it is important for the clinician to be aware of this potentially serious consequence of a commonly used drug, especially in the end-stage renal disease population. It is important for clinicians to be aware of this rare yet dangerous side effect of diphenhydramine. .

Drugs and ventricular repolarization in a general population: the Rotterdam Study

PURPOSE

Prolonged ventricular repolarization (measured as heart-rate corrected QT (QTc) prolongation or JT-interval prolongation) is a risk factor for ventricular arrhythmias and can be drug-induced. Drugs can be classified as having known or possible QTc-prolonging properties. Regulatory agencies recommend avoiding concomitant use of multiple QTc-prolonging drugs, but evidence is lacking to what degree ventricular repolarization is influenced by concomitant use of these drugs.

METHODS

Within a population-based cohort of persons aged 45 years and older, with up to five electrocardiograms recorded per participant between 1991 and 2010, we used generalised estimating equations to study the association between concomitant use of multiple QTc-prolonging drugs and repolarization duration.

RESULTS

The study population consisted of 13 009 participants with 26 908 electrocardiograms. With the addition of a second or third QTc-prolonging drug there was no substantial increase in QTc and JT interval and no increased risk of a prolonged QTc interval, compared to use of one QTc-prolonging drug. There was a large difference between the effect of one known or one possible QTc-prolonging drugs on QTc interval: 15 ms for known, and 3 ms for possible QTc-prolonging drugs.

CONCLUSIONS

In this study, the added prolongation in users of two or three QTc-prolonging drugs on QTc was small. There was a large difference in QTc prolongation between known and possible QTc-prolonging drugs. Further research in larger or high-risk populations is needed to establish whether it is safe to use multiple QTc-prolonging drugs concomitantly to prevent that the current advice might unnecessarily withhold beneficial drugs from patients.

Improving Detection of Arrhythmia Drug-Drug Interactions in Pharmacovigilance Data through the Implementation of Similarity-Based Modeling

Identification of Drug-Drug Interactions (DDIs) is a significant challenge during drug development and clinical practice. DDIs are responsible for many adverse drug effects (ADEs), decreasing patient quality of life and causing higher care expenses. DDIs are not systematically evaluated in pre-clinical or clinical trials and so the FDA U. S. Food and Drug Administration relies on post-marketing surveillance to monitor patient safety. However, existing pharmacovigilance algorithms show poor performance for detecting DDIs exhibiting prohibitively high false positive rates. Alternatively, methods based on chemical structure and pharmacological similarity have shown promise in adverse drug event detection. We hypothesize that the use of chemical biology data in a post hoc analysis of pharmacovigilance results will significantly improve the detection of dangerous interactions. Our model integrates a reference standard of DDIs known to cause arrhythmias with drug similarity data. To compare similarity between drugs we used chemical structure (both 2D and 3D molecular structure), adverse drug side effects, chemogenomic targets, drug indication classes, and known drug-drug interactions. We evaluated the method on external reference standards. Our results showed an enhancement of sensitivity, specificity and precision in different top positions with the use of similarity measures to rank the candidates extracted from pharmacovigilance data. For the top 100 DDI candidates, similarity-based modeling yielded close to twofold precision enhancement compared to the proportional reporting ratio (PRR). Moreover, the method helps in the DDI decision making through the identification of the DDI in the reference standard that generated the candidate.

Rare Incidence of Ventricular Tachycardia and Torsades de Pointes in Hospitalized Patients With Prolonged QT Who Later Received Levofloxacin: A Retrospective Study

OBJECTIVE

To determine the incidence of ventricular tachycardia and ventricular fibrillation in patients with prolonged corrected QT interval (QTc) who received levofloxacin through retrospective chart review at a tertiary care teaching hospital in the United States.

PATIENTS AND METHODS

We selected 1004 consecutive hospitalized patients with prolonged QTc (>450 ms) between October 9, 2009 and June 12, 2012 at our institution. Levofloxacin was administered orally and/or intravenously and adjusted to renal function in the inpatient setting. The primary outcome measure was sustained ventricular tachycardia recorded electrocardiographically.

RESULTS

With a median time from the start of levofloxacin use to hospital discharge (or death) of 4 days (range, 1-94 days), only 2 patients (0.2%; 95% CI, 0.0%-0.7%) experienced the primary outcome of sustained ventricular tachycardia after the initiation of levofloxacin use.

CONCLUSION

In this study, the short-term risk for sustained ventricular tachycardia in patients with a prolonged QTc who subsequently received levofloxacin was very rare. These results suggest that levofloxacin may be a safe option in patients with prolonged QTc; however, studies with longer follow-up are needed.

Antimalarial activity of 4-amidinoquinoline and 10-amidinobenzonaphthyridine derivatives

Chloroquine (CQ) has been used as first line malaria therapeutic drug for decades. Emergence of CQ drug-resistant Plasmodium falciparum malaria throughout endemic areas of the world has limited its clinical value. Mefloquine (MQ) has been used as an effective malaria prophylactic drug due to its being long-acting and having a high potency against blood stage P. falciparum (Pf). However, serious CNS toxicity of MQ has compromised its clinical value as a prophylaxis drug. Therefore, new and inexpensive antimalarial drugs with no cross-resistance to CQ or CNS toxicity are urgently needed to combat this deadly human disease. In this study, a series of new 4-amidinoquinoline (4-AMQ) and 10-amidinobenzonaphthyridine (10-AMB) derivatives were designed, prepared, and assessed to search for new therapeutic agents to replace CQ and MQ. The new derivatives displayed high activity in vitro and in vivo, with no cross-resistance to CQ, and none were toxic in mice up to 160 mpk × 3. The best compound shows IC50 < 1 ng/mL against D6, W2 and C235 Pf clones, low inhibitory activity in hERG K(+) channel blockage testing, negativity in the Ames test, and 5/5 cure @ <15 mpk × 3 in mice infected with Plasmodium berghei. In addition to these desirable pharmacological profiles, compound 13b, one of the most active compounds, is metabolically stable in both human and mouse liver microsomal preparations and has a plasma t(1/2) of 50 h in mice, which made it a good MQ replacement candidate.

A thorough QT study to evaluate the effects of therapeutic and supratherapeutic doses of delafloxacin on cardiac repolarization

A randomized, double-blind, placebo-controlled, 4-period crossover study was conducted in 52 healthy adults to assess the effect of delafloxacin on the corrected QT (QTc) interval. The QT interval, corrected for heart rate using Fridericia's formula (QTcF), was determined predose and at 0.5, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, 5, 6, 12, 18, and 24 h after dosing with delafloxacin at 300 mg intravenously (i.v.; therapeutic), delafloxacin at 900 mg i.v. (supratherapeutic), moxifloxacin at 400 mg orally (p.o.; positive control), and placebo. The pharmacokinetic profile of delafloxacin was also evaluated. At each time point after delafloxacin administration, the upper limit of the 90% confidence interval (CI) for the placebo-corrected change from the predose baseline in QTcF (ΔΔQTcF) was less than 10 ms (maximum, 3.9 ms at 18 h after dosing), indicating an absence of a clinically meaningful increase in the QTc interval. The lower limit of the 90% CI of ΔΔQTcF for moxifloxacin versus placebo was longer than 5 ms at all 5 time points selected for assay sensitivity analysis, demonstrating that the study was adequately sensitive to assess QTc prolongation. There was no positive relationship between delafloxacin plasma concentrations and ΔΔQTcF. Treatment-emergent adverse events (AEs) were more frequent among subjects receiving a single supratherapeutic dose of 900 mg delafloxacin. There were no deaths, serious AEs, or AEs leading to study discontinuation and no clinically meaningful abnormalities in laboratory values or vital signs observed at any time point after any dose of the study drug.

Efeitos cardiotóxicos resultantes da interação da risperidona com diuréticos tiazídicos

Antipsicóticos atípicos têm sua ação em doses que podem produzir efeitos colaterais importantes. A risperidona é o antipsicótico atípico de nova geração mais utilizado na atualidade e seu uso está associado a tratamento de esquizofrenia, transtornos psicóticos, episódios de mania e nos distúrbios de comportamento, entre outros. Os efeitos adversos mais importantes estão relacionados ao sistema nervoso central e autônomo, sistema endócrino e sistema cardiovascular. Neste último, pode haver efeitos inotrópicos negativos e alterações no eletrocardiograma, como prolongamento do intervalo QT, podendo causar taquicardia e arritmias. Relatamos um caso de um homem de 48 anos com história de delírio persecutório após ser ameaçado no trabalho, que estava sendo tratado com risperidona e paroxetina. Por não haver melhora, suas doses foram aumentadas e o paciente apresentou alargamento do intervalo QTc, com diminuição da amplitude da onda T e aumento da onda U, e hipocalemia. Além disso, o paciente era hipertenso e estava em uso de hidroclorotiazida. A risperidona tem o potencial de bloquear o componente rápido do canal cardíaco de potássio e isso prolonga o processo de repolarização dos ventrículos, podendo causar torsade de pointes, morte súbita e arritmias. Já a hidroclorotiazida causa hipocalemia, provocando alterações na contração e relaxamento do miocárdio. Houve interação medicamentosa grave entre duas drogas com potencial arritmogênico, o que levou às alterações no eletrocardiograma e produziu sintomas danosos ao paciente. A troca do antipsicótico atípico para um típico e da hidroclorotiazida por um diurético que não causa hipocalemia trouxe melhoras ao paciente.

Contrasting Time- and Rate-Based Approaches for the Assessment of Drug-Induced QT Changes

The authors aim to highlight the pitfalls of different validated methods used for the assessment of drugs' effect on QT duration. Digital 12-lead Holter electrocardiograms were recorded at baseline and after a single dose of sotalol in 39 healthy subjects (age = 27.4 +/- 8.0 years). Using both time- and rate-based approaches, the authors obtained averaged QRS-T complexes every minute ("time bins") and at different RR intervals ("rate bins"). Time bins were corrected for heart rate using a subject-specific approach. The individual alpha coefficients increased from placebo (0.309 +/- 0.052) to sotalol (0.454 +/- 0.136), P < .0001. When the placebo individual alpha coefficients were applied to correct the QT interval on sotalol, the changes were >5 ms smaller than those obtained using the ON drug alpha coefficients. The "rate"-averaging process leads to a complete loss of the time course of drug effect. In conclusion, the individual correction formula calculated from the placebo condition cannot always be used for QT correction on the drug.

Effects of dose ranging of adenosine infusion on electrocardiographic findings during and after general anesthesia

PURPOSE

To assess changes in the electrocardiogram (ECG) associated with intraoperative infusion of adenosine in patients undergoing open abdominal gynecological surgery.

METHODS

One hundred and sixty-six patients undergoing gynecological surgery were randomly assigned to receive one of four doses of adenosine infusion (25, 50, 100, or 200 μg/kg/min) or matching placebo. Study drug administration was started at skin incision and discontinued at end of surgery. A standardized general anesthetic regimen was used and adjusted based on hemodynamic and bispectral index values. Heart rate and rhythm variables, and PR, QRS, QT, and QTc intervals were recorded from 12-lead ECGs before anesthesia and immediately after patient arrival in the postanesthesia care unit. In addition, a rhythm strip was obtained during administration of the loading dose of the study drug. ECG variables were compared within and between groups. Incidence of ECG and hemodynamic abnormalities was recorded.

RESULTS

One hundred and fifty-one subjects had a full set of electrocardiographic data: placebo (n = 38), group adenosine 25 μg/kg/min (n = 31), group adenosine 50 μg/kg/min (n = 29), group adenosine 100 μg/kg/min (n = 28), and group adenosine 200 μg/kg/min (n = 25). Statistically significant postoperative QTc prolongation was observed in all study groups when compared with baseline except for the adenosine 200 μg/kg/min group. However, these changes from baseline were not different among the groups. There were also no significant differences in PR, QRS, and QT intervals between the treatment groups.

CONCLUSION

There was no difference in QTc prolongation following intraoperative administration of adenosine infusion compared with placebo during isoflurane general anesthesia. However, QTc prolongation is common following general anesthesia.

Symptomatic Bradycardia, Syncope, and Prolonged QTc Interval Associated with Dronedarone Therapy

Objective

To report a case of symptomatic bradycardia, prolonged QT interval, and syncope associated with dronedarone in a patient with atrial fibrillation who was maintained in sinus rhythm.

Case Summary

A 58-year-old man presented to the emergency department with a chief complaint of chest pain and “passing out.” Three months prior, dronedarone had been initiated for maintenance of sinus rhythm. An initial electrocardiogram (ECG) revealed normal sinus rhythm with a prolonged corrected QT (QTc) interval of 645 ms. Upon hospital admission, dronedarone was discontinued. Approximately 17 hours after hospitalization and 35 hours after the last ingested dronedarone dose, a repeat ECG revealed a QTc interval of 457 ms, and the patient reported symptomatic improvement. The patient was discharged home after a 3-day hospital stay without further event. The Naranjo Adverse Drug Reaction Probability Scale indicated a probable relationship between the patient's symptoms and dronedarone.

Discussion

Dronedarone is an antiarrhythmic drug that exhibits multiple mechanisms of action, including potassium, sodium, and calcium channel blockade, in addition to antiadrenegic activity. In clinical evaluations of dronedarone therapy, dronedarone was associated with a mean decrease in resting heart rate and potential to prolong the QT interval by 10 ms. These effects may result in clinically significant outcomes, as was observed in this patient.

Conclusions

This case of symptomatic bradycardia and prolonged QTc interval emphasizes the importance of monitoring the heart rate and ECG in patients prescribed dronedarone, particularly in those on concomitant drug therapy that may precipitate these events.

Prevalence of potential drug-drug interactions in bone marrow transplant patients

OBJECTIVE

To assess the prevalence of potential drug-drug interactions (DDIs) in bone marrow transplantation (BMT) patients at the time of pre-infusion (day -1), to describe the potential DDIs and assess their frequency and severity.

SETTING

The study was developed in a tertiary care hospital in São Paulo, Brazil.

METHOD

Cross-sectional study based on examining the medical prescriptions from the pre-infusion day (day -1) of 70 BMT patients. Potential DDIs were analyzed using Drug-Reax(®) and categorized according to levels of severity, evidence, and onset (rapid and delayed). Only interactions of major or moderate severity were included in the potential DDI analysis.

MAIN OUTCOME MEASURE

Prevalence of potential DDIs in patients during the preinfusion phase of BMT.

RESULTS

Data were analysed for 70 BMT patients. The median age was 36.5 years; 52.9% (37) of the patients were male, and 65.7% (46) were undergoing autologous BMT. The patients received a median of 8 drugs each. Up to 128 potential DDIs were detected, 60.0% (42) of patients had at least 1 potential DDI and 21.4% (15) were exposed to at least 1 major potential DDI. The most commonly involved drugs were cyclosporine (9, 28.1%), phenytoin (8, 25%) and fluconazole (5, 15.6%). Most potential DDIs had moderate severity (110, 85.9%), a pharmacokinetic mechanism (67, 52.3%), and were classified as delayed onset (106, 82.8%). For major interactions, fluconazole + sulfamethoxazole/trimethoprim, diazepam + fentanyl, fluconazole + levofloxacin and fentanyl + fluconazole were the most frequent.

CONCLUSIONS

The prevalence of potential DDIs during the conditioning period of BMT was high as a consequence of the therapeutic complexity of the procedure. Most potential DDIs identified in the study may result in clinically relevant consequences as they could lead to nephrotoxicity, cardiotoxicity, and other undesirable adverse effects. Careful monitoring of clinical and laboratory parameters is essential to ensure a successful BMT and to avoid adverse drug events related to DDI.

Assessment of sotalol prescribing in a community hospital: opportunities for clinical pharmacist involvement

OBJECTIVE

Due to risk of serious adverse drug events (ADEs) sotalol use is limited in renal insufficiency and heart failure. To reduce potential life-threatening ADEs, medication safety initiatives that ensure appropriate dosing of sotalol are necessary. Pharmacist-managed renal dosing assessment programmes ensure appropriate dosing of renally eliminated medications. A prospective medication safety evaluation was conducted to assess the need to include sotalol in an existing renal dosing assessment programme as well as the impact of clinical pharmacist assessment on sotalol prescribing.

METHODS

Patients in a 736-bed community hospital, receiving sotalol during a 6-week period, were prospectively evaluated. Information was collected on indication, dosing, concomitant disease states and medications, renal function, QTc length, symptoms of toxicity and readmissions. Pharmacist recommendations were made when necessary and were followed to determine acceptance rate and patient outcomes.

KEY FINDINGS

Thirty-six patients were prescribed sotalol for atrial tachyarrhythmias. Thirty-two (89%) were dosed inappropriately with respect to renal function. Twenty (56%) had left-ventricular dysfunction as defined by an ejection fraction of ≤ 40%. At time of initial assessment, 15 (42%) were exhibiting signs of potential sotalol toxicity. Pharmacists provided recommendations regarding discontinuation or dosage adjustment on 32 patients with a 38% full and a 12% partial acceptance rate. All-cause readmission rates for patients receiving appropriate therapy, including those after pharmacist recommendations were accepted (Group A; n=16), were compared to those remaining on inappropriate therapy (Group B; n=20). Readmission rates within 6 months differed between groups (31% for Group A, 55% for Group B; P=0.095, odds ratio 3.7).

CONCLUSION

This medication safety evaluation suggests the need for pharmacist assessment in patients receiving sotalol. Dosage adjustment or avoidance in patients with renal insufficiency, heart failure and other relative contraindications is often necessary to avoid toxicity. Sotalol was inappropriately prescribed in the majority of patients secondary to renal insufficiency. Based on this evaluation, it was recommended to add sotalol to the institution's pharmacist-managed renal dosing adjustment programme. Ensuring clinical pharmacist assessment when sotalol is prescribed can help reduce potential life-threatening ADEs and hospital readmissions.

The relation between QT interval and T-wave variables in hypertensive patients

BACKGROUND

The standard 12-lead ECG (electrocardiogram) continues to be the most frequently recorded noninvasive test in medicine. A prolonged ECG QT interval and Tpeak-Tend (Tpe) interval are predictors of ventricular arrhythmia and sudden cardiac death.

AIM

The aim of this study is to analyze the relation between QT interval and T-wave variables in hypertensive patients, with and without left ventricular hypertrophy (LVH).

MATERIALS AND METHODS

Fifty-nine consecutive patients with grade 2 essential hypertension were included in the study. They underwent standard 12-lead ECG, and QT intervals: QTmax (the maximal duration of the QT interval in the 12 ECG leads), QTc (heart rate corrected QTmax), QTm (mean QT interval), QTII (the QT interval in lead DII), QTcII (heart rate corrected QTII), and QTd (QT dispersion); and T-wave variables: T0e (T wave duration), T0em (mean T0e), Tpe, Tpem (mean Tpem), Ta (T wave amplitude), and Tam (mean Ta) were manually assessed. LVH was diagnosed using both echocardiography and the ECG criteria.

RESULTS

QTc was prolonged in 41 patients (69%). Multiple regression analysis revealed a significant association between QT intervals and T-wave variables: QTmax and Tpe (P = 0.015), QTd and Tpe (P = 0.022) and Ta (P = 0.004), and Tpe with QTd and T0e (P < 0.05). A moderate but significant correlation was found between Tpe and QTmax, Tpe and QTII, and Ta and QTd. A prolonged QTc was more prevalent in hypertensive patients with LVH (85%), compared to hypertensive patients without LVH (50%). QTm, QTd, QTII, Tpe, Tpem were significantly elevated (P < 0.05) in patients with LVH.

CONCLUSIONS

Hypertension is associated with an increased prevalence of prolonged QT intervals. QT intervals and T-wave variables are closely connected in hypertensive patients. QTm, T0em, Tpem, and Tam, do not provide significant additional information compared to QTmax, T0e, Tpe, and Ta. Left ventricular hypertrophy is associated with prolonged QT interval and Tpeak-Tend interval in hypertensive patients.

Clinically relevant drug interactions between anticancer drugs and psychotropic agents

Drug interactions are commonly seen in the treatment of cancer patients. Psychotropics are often indicated for these patients since they may also suffer from pre-existing psychological disorders or experience insomnia and anxiety associated with cancer therapy. Thus, the risk of anticancer drug (ACD)-psychotropic drug-drug interactions (DDIs) is high. Drug interactions were compiled from the British National Formulary (53rd edn), Lexi-Comp's Drug Information Handbook (15th edn), Micromedex (v5.1), Hansten & Horn's Drug Interactions (2000) and Drug Interaction Facts (2008 edn). Product information of the individual drugs, as well as documented literature on ACD-psychotropic interactions from PubMed and other databases was also incorporated. This paper identifies clinically important ACD-psychotropic DDIs that are frequently observed. Pharmacokinetic DDIs were observed for tyrosine kinase inhibitors, corticosteroids and antimicrotubule agents due to their inhibitory or inductive effects on cytochrome P450 isoenzymes. Pharmacodynamic DDIs were identified for thalidomide with central nervous system depressants, procarbazine with antidepressants, myelosuppressive ACDs with clozapine and anthracyclines with QT-prolonging psychotropics. Clinicians should be vigilant when psychotropics are prescribed concurrently with ACDs. Close monitoring of plasma drug levels should be carried out to avoid toxicity in the patient, as well as to ensure adequate chemotherapeutic and psychotropic coverage.

Dose study of the multikinase inhibitor, LY2457546, in patients with relapsed acute myeloid leukemia to assess safety, pharmacokinetics, and pharmacodynamics

Background:

Acute myeloid leukemia (AML) is a life-threatening malignancy with limited treatment options in chemotherapy-refractory patients. A first-in-human dose study was designed to investigate a safe and biologically effective dose range for LY2457546, a novel multikinase inhibitor, in patients with relapsed AML.

Methods:

In this nonrandomized, open-label, dose escalation Phase I study, LY2457546 was administered orally once a day. Safety, pharmacokinetics, changes in phosphorylation of target kinases in AML blasts, and risk of drug–drug interactions (DDI) were assessed.

Results:

Five patients were treated at the starting and predicted minimal biologically effective dose of 50 mg/day. The most commonly observed adverse events were febrile neutropenia, epistaxis, petechiae, and headache. The majority of adverse events (81%) were Grade 1 or 2. One patient had generalized muscle weakness (Grade 3), which was deemed to be a dose-limiting toxicity. Notably, the pharmacokinetic profile of LY2457546 showed virtually no elimination of LY2457546 within 24 hours, and thus prevented further dose escalation. No significant DDI were observed. Ex vivo flow cytometry studies showed downregulation of the phosphoproteins, pcKIT, pFLT3, and pS6, in AML blasts after LY2457546 administration. No medically relevant responses were observed in the five treated patients.

Conclusion:

No biologically effective dose could be established for LY2457546 in chemotherapy-resistant AML patients. Lack of drug clearance prevented safe dose escalation, and the study was terminated early. Future efforts should be made to develop derivatives with a more favorable pharmacokinetic profile.

Machine learning algorithms for the prediction of hERG and CYP450 binding in drug development

IMPORTANCE OF THE FIELD

The cost of developing new drugs is estimated at approximately $1 billion; the withdrawal of a marketed compound due to toxicity can result in serious financial loss for a pharmaceutical company. There has been a greater interest in the development of in silico tools that can identify compounds with metabolic liabilities before they are brought to market.

AREAS COVERED IN THIS REVIEW

The two largest classes of machine learning (ML) models, which will be discussed in this review, have been developed to predict binding to the human ether-a-go-go related gene (hERG) ion channel protein and the various CYP isoforms. Being able to identify potentially toxic compounds before they are made would greatly reduce the number of compound failures and the costs associated with drug development.

WHAT THE READER WILL GAIN

This review summarizes the state of modeling hERG and CYP binding towards this goal since 2003 using ML algorithms.

TAKE HOME MESSAGE

A wide variety of ML algorithms that are comparable in their overall performance are available. These ML methods may be applied regularly in discovery projects to flag compounds with potential metabolic liabilities.

Multipolar QRST isointegral maps and QT dispersion in old myocardial infarction

Chronic myocardial infarction (CMI) may create, due to structural heterogeneity, abnormal electrophysiological substrates which trigger re-entrant life-threatening ventricular arrhythmias.

METHODS

Electrical instability is assessed using body surface mapping (BSM) [multipolar isointegral QRST maps (mp I(QRST))] and 12-lead ECG (QT dispersion: QTd: the difference between maximal and minimal QT interval). The aim was to find the relation between mp I(QRST) and QTd in CMI patients.

RESULTS

The 32 CMI patients, underwent 12-lead ECG and 64-lead BSM. The 80% (25) of the patients had mp I(QRST) maps. QTd was larger in patients with mp than those with dipolar maps (dp): 170 +/- 20 ms in mp vs 94 +/- 19 ms in dp, respectively. The latter, mp I(QRST) was associated with a decrease of maximum and a stronger minimum.

CONCLUSIONS

Multipolar I(QRST) is associated with a loss of maximum values and increased absolute values of the minimum in CMI patients. I(QRST) and QTd provide similar information in predicting postinfarction arrhythmia risk.

Drug-Induced QTc-Interval Prolongation in the Intensive Care Unit: Incidence and Predictors

There is a paucity of information regarding QTc prolongation in critically ill patients. A prospective observational study was conducted to assess the incidence and predictors of QTc prolongation associated with medications in intensive care unit (ICU) patients. Consecutive adult patients prescribed prespecified QTc-prolonging medications were assessed for development of the combined incidence of QTc >500 ms at anytime and QTc increase >60 ms above baseline. Over 3 months, 200 consecutive patients (63 ± 18 years; 52% female; 73% Caucasian; baseline QTc 447.3 ± 51.5 ms) were evaluated. The primary end point occurred in 48% of the patients (QTc >500 ms 40%, QTc increase >60 ms 29%). The majority of patients experienced a QTc >470 or 450 ms (60.5%). Mean increase in QTc at 48 hours was 20 ± 35 ms. Upon multivariate analysis, length of stay [odds ratio 1.30, 95% confidence interval (1.15, 1.47)] and baseline QTc [1.01 (1.01, 1.02)] were associated with an increased risk for the primary end point, while beta-blockers [0.41 (0.20, 0.81)] were associated with a risk reduction. In conclusion, increased risk of proarrhythmia, as assessed by QTc prolongation, occurs in the majority of ICU patients when prescribed medications with electrophysiologic properties. Increased vigilance is warranted. The possible protective effect of beta-blockers requires confirmation.

The time course of new T-wave ECG descriptors following single- and double-dose administration of sotalol in healthy subjects

INTRODUCTION

The aim of the study was to assess the time course effect of IKr blockade on ECG biomarkers of ventricular repolarization and to evaluate the accuracy of a fully automatic approach for QT duration evaluation.

METHODS

Twelve-lead digital ECG Holter was recorded in 38 healthy subjects (27 males, mean age = 27.4 + or - 8.0 years) on baseline conditions (day 0) and after administration of 160 mg (day 1) and 320 mg (day 2) of d-l sotalol. For each 24-hour period and each subject, ECGs were extracted every 10 minutes during the 4-hour period following drug dosage. Ventricular repolarization was characterized using three biomarker categories: conventional ECG time intervals, principal component analysis (PCA) analysis on the T wave, and fully automatic biomarkers computed from a mathematical model of the T wave.

RESULTS

QT interval was significantly prolonged starting 1 hour 20 minutes after drug dosing with 160 mg and 1 hour 10 minutes after drug dosing with 320 mg. PCA ventricular repolarization parameters sotalol-induced changes were delayed (>3 hours). After sotalol dosing, the early phase of the T wave changed earlier than the late phase prolongation. Globally, the modeled surrogate QT paralleled manual QT changes. The duration of manual QT and automatic surrogate QT were strongly correlated (R(2) = 0.92, P < 0.001). The Bland and Altman plot revealed a nonstationary systematic bias (bias = 26.5 ms + or - 1.96*SD = 16 ms).

CONCLUSIONS

Changes in different ECG biomarkers of ventricular repolarization display different kinetics after administration of a potent potassium channel blocker. These differences need to be taken into account when designing ventricular repolarization ECG studies.

QTc interval prolongation in children with Turner syndrome: the results of exercise testing and 24-h ECG

BACKGROUND

Turner syndrome (TS) is the most common sex chromosome abnormality in females. Recently, a prolongation of the rate-corrected QT (QTc) interval in the electrocardiogram (ECG) of TS patients has been reported. A prolonged QTc interval has been correlated to an increased risk for sudden cardiac death, and medical treatment is warranted in patients with congenital long QT syndrome (LQTS). Additionally, several drugs of common use are contraindicated in LQTS because of their effects on myocardial repolarization. The importance of the QTc prolongation in TS patients is not known at present.

MATERIALS AND METHODS

Eighteen TS patients with a prolonged QTc interval (group 1) and 11 TS patients with a normal QTc interval (group 2) (mean age 12.6+/-3.1 vs. 11.8+/-2.1 years, respectively) were tested. The QTc interval was calculated during exercise testing and during 24-h ECG recordings.

RESULTS

None of the patients experienced adverse cardiac events during the tests. The mean QTc interval decreased from 0.467 to 0.432 s in group 1 and from 0.432 to 0.412 s in group 2. During the 24-h ECG, the maximum QTc interval was significantly prolonged in group 1 (0.51 vs. 0.465 s, p<0.05, respectively). We conclude that exercise testing and 24-h ECG recording provide valuable information about the cardiac risk in the single TS patient with a prolonged QTc interval. This helps in counseling these girls, as clear therapeutic guidelines are currently lacking.

Pharmacist monitoring of QTc interval-prolonging medications in critically ill medical patients: a pilot study

BACKGROUND

No data exist regarding the value of pharmacist monitoring of drugs associated with QTc interval prolongation.

OBJECTIVE

To assess the capability, clinical impact, and economic impact of pharmacists monitoring for drug-induced QTc interval prolongation in critically ill medical adult patients.

METHODS

In a prospective, parallel-group study, 149 consecutive medical intensive care unit (ICU) patients prescribed a QTc interval-prolonging drug at the Los Angeles County + University of Southern California Medical Center were assigned on alternating days to an intervention group (clinical pharmacist on physician team monitored drugs using a standardized algorithm) or a standard care group (team without pharmacist using an algorithm). The monitoring algorithm used daily assessments of electrocardiograms and laboratory data to generate pharmacotherapeutic recommendations. The primary endpoint was the frequency of QTc interval prolongation (>500 msec at any time or an increase > or =60 msec over baseline). Secondary endpoints included QTc interval greater than 470 msec in women or greater than 450 msec in men, mean increase in QTc interval at 48 hours, recommendation acceptance rate, and cost of care.

RESULTS

QTc interval prolongation occurred less frequently in the intervention group compared with the standard care group (19% vs 39%, respectively; p = 0.006). Incidence of QTc interval greater than 500 msec (13% vs 33%, respectively; p = 0.003) was also lower in the intervention group. Incidence of QTc interval increase of 60 msec or more over baseline (12% vs 21%, respectively; p = 0.12) and increase in QTc interval at 48 hours over baseline (mean +/- SD; 6.4 +/- 40.8 vs 18.2 +/- 42.3 msec, respectively; p = 0.097) were not significantly different between the groups. Algorithm-generated recommendations were accepted 70% of the time by the intervention group physician team. Total cost and cost per day were not significantly different between groups.

CONCLUSIONS

In this preliminary study, pharmacist monitoring of QTc interval-prolonging drugs using a simple algorithm was feasible and reduced the risk of QTc interval prolongation. Further studies that monitor other proarrhythmic medications are warranted.

T-wave morphology parameters based on principal component analysis reproducibility and dependence on T-offset position

BACKGROUND

T-wave morphology parameters based on principal component analysis (PCA) are candidate to better understand the relation between QT prolongation and torsades de pointes. We aimed to assess the repeatability and to determine the influence of T-end position on PCA parameters.

METHODS

Digital ECGs recorded from 30 subjects were used to assess short term (5 minutes), circadian and long-term (28 days) repeatability of PCA parameters. The T-end cursor position was moved backward and forward (+/- 8 ms) from its optimal position. We calculated QRS-T angle, PCA ratio, and T-wave residuum (TWR).

RESULTS

At long-term evaluation, coefficients of variation were 11.3 +/- 9.9%, 11.7 +/- 7.1%, and 23.0 +/- 22.0% for the QRS-T angle, PCA ratio, TWR, respectively. After moving the T-end cursor, repeatability was 0.42 +/- 0.2%, 1.00 +/- 1.04%, 4.0 +/- 4.2% for the same PCA parameters.

CONCLUSIONS

T-wave morphology parameters based on PCA are reproducible with the exception of TWR and QRS-T angle. In addition, PCA is robust, showing only little dependence on T-end cursor position. These data should be taken into account for safety pharmacology trials.

A composite screening tool for medication reviews of outpatients: general issues with specific examples

Regular performance of medication reviews is prominent among methods that have been advocated to reduce the extent and seriousness of drug-related problems, such as adverse drug reactions, drug-disease interactions, drug-drug interactions, drug ineffectiveness and cost ineffectiveness. Several screening tools have been developed to guide practising healthcare professionals and researchers in reviewing the medication patterns of elderly patients; however, each of these tools has its own limitations. This review discusses a wide range of general prescription-, treatment- and patient-related issues that should be taken into account when reviewing medication patterns by implicit screening. These include generic and therapeutic substitution; potentially superfluous or inappropriate medications; potentially inappropriate dosages or duration of treatment; drug-disease and drug-drug interactions; under-treatment; making use of laboratory test results; patient adherence, experiences and habits; appropriate dosage forms and packaging. A broad selection of specific examples and references that can be used as a basis for explicit screening of medication patterns in outpatients is also offered.