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Ester Donado I?aki Izquierdo I?aki Pérez Olga García Rosa Ma Antonijoan Ignaci Gich Anna Solans Juana Pe?a Joel Morganroth Manuel J Barbanoj 《British journal of clinical pharmacology》2010,69(4):401-410
AIMS
To evaluate the effects of therapeutic and supratherapeutic doses of rupatadine on cardiac repolarization in line with a ‘thorough QT/QTc study’ protocol performed according to International Conference on Harmonization guidelines.METHODS
This was a randomized (gender-balanced), parallel-group study involving 160 healthy volunteers. Rupatadine, 10 and 100 mg day−1, and placebo were administered single-blind for 5 days, whilst moxifloxacin 400 mg day−1 was given on days 1 and 5 in open-label fashion. ECGs were recorded over a 23-h period by continuous Holter monitoring at baseline and on treatment days 1 and 5. Three 10-s ECG samples were downloaded at regular intervals and were analysed independently. The primary analysis of QTc was based on individually corrected QT (QTcI). Treatment effects on QTcI were assessed using the largest time-matched mean difference between the drug and placebo (baseline-subtracted) for the QTcI interval. A negative ‘thorough QT/QTc study’ is one where the main variable is around ≤5 ms, with a one-sided 95% confidence interval that excludes an effect >10 ms.RESULTS
The validity of the trial was confirmed by the fact that the moxifloxacin-positive control group produced the expected change in QTcI duration (around 5 ms). The ECG data for rupatadine at both 10 and 100 mg showed no signal effects on the ECG, after neither single nor repeated administration. Furthermore, no pharmacokinetic/pharmacodynamic relationship, gender effects or clinically relevant changes in ECG waveform outliers were observed. No deaths or serious or unexpected adverse events were reported.CONCLUSIONS
This ‘thorough QT/QTc study’ confirmed previous experience with rupatadine and demonstrated that it had no proarrhythmic potential and raised no concerns regarding its cardiac safety. 相似文献3.
Qian Chen Yan-mei Liu Yun Liu Boaz Mendzelevski Dennis Chanter Hua-hua Pu Gang-yi Liu Onglee Weng Chao-ying Hu Wei Wang Chen Yu Jing-ying Jia 《Acta pharmacologica Sinica》2015,36(4):448-453
Aim:
To investigate the QT/QTc effects of orally administered moxifloxacin in healthy Chinese volunteers.Methods:
This was a single-blinded, randomized, single-dose, placebo-controlled, two-period cross-over study. A total of 24 healthy Chinese volunteers were enrolled, randomly assigned to two groups: one group received moxifloxacin (400 mg, po) followed by placebo with a 7-d interval, another group received placebo followed by moxifloxacin with a 7-d interval. On the days of dosing, 12-lead 24 h Holter ECGs were recorded and evaluated by an ECG laboratory blind to the treatments. Blood samples were collected to determine plasma concentrations of moxifloxacin.Results:
The orally administered moxifloxacin significantly prolonged the mean QTc at all time points except 0.5 h post-dose. The largest time-matched difference in the QTcI was 8.35 ms (90% CI: 5.43, 11.27) at 4 h post-dose. The peak effect on QTcF was 9.35 ms (90% CI: 6.36, 12.34) at 3 h post-dose. A pharmacokinetic-QTc model suggested a 2.084 ms increase in the QTc interval for every 1000 ng/mL increase in plasma concentration of moxifloxacin. In addition, the orally administered moxifloxacin was well tolerated by the subjects.Conclusion:
Orally administered moxifloxacin significantly prolongs QTc, which supports its use as a positive control in ICH-E14 TQT studies in Chinese volunteers. 相似文献4.
Not-in-trial simulation I: Bridging cardiovascular risk from clinical trials to real-life conditions
Anne S Y Chain Jeanne P Dieleman Charlotte van Noord Albert Hofman Bruno H Ch Stricker Meindert Danhof Miriam C J M Sturkenboom Oscar Della Pasqua 《British journal of clinical pharmacology》2013,76(6):964-972
Aims
The assessment of heart rate-corrected QT (QTc) interval prolongation relies on the evidence of drug effects in healthy subjects. This study demonstrates the relevance of pharmacokinetic–pharmacodynamic (PKPD) relationships to characterize drug-induced QTc interval prolongation and explore the discrepancies between clinical trials and real-life conditions.Methods
d,l-Sotalol data from healthy subjects and from the Rotterdam Study cohort were used to assess treatment response in a phase I setting and in a real-life conditions, respectively. Using modelling and simulation, drug effects at therapeutic doses were predicted in both populations.Results
Inclusion criteria were shown to restrict the representativeness of the trial population in comparison to real-life conditions. A significant part of the typical patient population was excluded from trials due to weight and baseline QTc interval criteria. Relative risk was significantly different between sotalol users with and without heart failure, hypertension, diabetes and myocardial infarction (P < 0.01). Although drug effects do cause an increase in the relative risk of QTc interval prolongation, the presence of diabetes represented an increase from 4.0 [95% confidence interval (CI) 2.7–5.8] to 6.5 (95% CI 1.6–27.1), whilst for myocardial infarction it increased from 3.4 (95% CI 2.3–5.13) to 15.5 (95% CI 4.9–49.3).Conclusions
Our findings show that drug effects on QTc interval do not explain the observed QTc values in the population. The prevalence of high QTc values in the real-life population can be assigned to co-morbidities and concomitant medications. These findings substantiate the need to account for these factors when evaluating the cardiovascular risk of medicinal products. 相似文献5.
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Background and Purpose
Status epilepticus is increasingly associated with cardiac injury in both clinical and animal studies. The current study examined ECG activity for up to 48 h following kainic acid (KA) seizure induction and compared the potential of atenolol and clonidine to attenuate this cardiac pathology.Experimental Approach
Sprague-Dawley rats (male, 300–350 g) were implanted with ECG and electrocorticogram electrodes to allow simultaneous telemetric recordings of cardiac and cortical responses during and after KA-induced seizures. Animals were randomized into saline controls, and saline vehicle-, clonidine- or atenolol-pretreated KA groups.Key Results
KA administration in the saline-pretreated group produced an immediate bradycardic response (maximal decrease of 28 ± 6%), coinciding with low-level seizure activity. As high-level seizure behaviours and EEG spiking increased, tachycardia also developed, with a maximum heart rate increase of 38 ± 7% coinciding with QTc prolongation and T wave elevation. Both clonidine and atenolol pretreatment attenuated seizure activity and reduced KA-induced changes in heart rate, QTc interval and T wave amplitude observed during both bradycardic and tachycardic phases in saline-pretreated KA animals. Clonidine, however, failed to reduce the power of EEG frequencies. Atenolol and to a lesser extent clonidine attenuated the cardiac hypercontraction band necrosis, inflammatory infiltration, and oedema at 48 h after KA, relative to the saline-KA group.Conclusions and Implications
Severe seizure activity in this model was clearly associated with altered ECG activity and cardiac pathology. We suggest that modulation of sympathetic activity by atenolol provides a promising cardioprotective approach in status epilepticus. 相似文献7.
Jorg Taubel Asif Naseem Tomohiko Harada Duolao Wang Radivoj Arezina Ulrike Lorch A John Camm 《British journal of clinical pharmacology》2010,69(4):391-400
AIMS
To characterize the effects of levofloxacin on QT interval in healthy subjects and the most appropriate oral positive control treatments for International Conference on Harmonization (ICH) E14 QT/QTc studies.METHODS
Healthy subjects received a single dose of levofloxacin (1000 or 1500 mg), moxifloxacin (400 mg) or placebo in a four-period crossover design. Digital 12-lead ECGs were recorded in triplicate. Measurement of QT interval was performed automatically with subsequent manual onscreen over-reading using electronic callipers. Blood samples were taken for determination of levofloxacin and moxifloxacin concentrations.RESULTS
Mean QTcI (QT interval corrected for heart rate using a correction factor that is applicable to each individual) was prolonged in subjects receiving moxifloxacin 400 mg compared with placebo. The largest time-matched difference in QTcI for moxifloxacin compared with placebo was observed to be 13.19 ms (95% confidence interval 11.21, 15.17) at 3.5 h post dose. Prolonged mean QTcI was also observed in subjects receiving levofloxacin 1000 mg and 1500 mg compared with placebo. The largest time-matched difference in QTcI compared with placebo was observed at 3.5 h post dose for both 1000 mg and 1500 mg of levofloxacin [mean (95%) 4.42 ms (2.44, 6.39) in 1000 mg and 7.44 ms (5.47, 9.42) in 1500 mg]. A small increase in heart rate was observed with levofloxacin during the course of the study. However, moxifloxacin showed a greater increase compared with levofloxacin.CONCLUSIONS
Both levofloxacin and moxifloxacin can fulfil the criteria for a positive comparator. The ICH E14 guidelines recommend a threshold of around 5 ms for a positive QT/QTc study. The largest time-matched difference in QTc for levofloxacin suggests the potential for use in more rigorous QT/QTc studies. This study has demonstrated the utility of levofloxacin on the assay in measuring mean QTc changes around 5 ms. 相似文献8.
Nevena M Maljuric Raymond Noordam Nikkie Aarts Maartje N Niemeijer Marten E van den Berg Albert Hofman Jan A Kors Bruno H Stricker Loes E Visser 《British journal of clinical pharmacology》2015,80(4):698-705
Aims
Selective serotonin re-uptake inhibitors (SSRIs), specifically citalopram and escitalopram, are thought to cause QTc prolongation, although studies have shown contradictory results. Nevertheless, a maximum citalopram dosage of 20 mg in high risk patients (e.g. >60 years of age) is recommended. We aimed to investigate the association between use of (individual) SSRIs and QTc in a population-based study in older adults.Methods
This study, which was part of the prospective Rotterdam Study (period 1991–2012), included participants with up to five electrocardiograms (ECGs). We used linear mixed models to compare QTcF (QT corrected according to Fridericia) measured during use of individual SSRIs with QTcF measured during non-use of any antidepressant. For citalopram, analyses were additionally restricted to a maximum dosage of 20 mg in participants aged 60 years and older.Results
We included 12 589 participants with a total of 26 620 ECGs of which 436 ECGs were made during SSRI use. The mean QTcF was similar during use of any drugs from the SSRI class and during non-use. After stratifying to individual SSRIs, ECGs recorded during use of citalopram had the longest QTc compared with ECGs recorded during non-use (+12.8 ms, 90% CI 7.5, 18.2). This result remained similar in the analysis comprising participants aged 60 years and older with a maximum prescribed daily dosage of 20 mg citalopram.Conclusions
Although no SSRI class effect was observed, use of citalopram was associated with a longer QTcF, even after considering the recommended restrictions. Other SSRIs may not give a clinically relevant QTcF prolongation. 相似文献9.
Aim:
The study was designed to establish relationship between the plasma concentration and QTc interval prolonging effect of fexofenadine and demonstrate the phenomenon of anticlockwise hysteresis.Materials and Methods:
Six subjects were given fexofenadine 60 mg tablet orally under stable conditions, and their drug concentrations were measured at regular intervals. At predetermined time, their ECGs were recorded. Data were analyzed and plotted graphically.Design and Setting:
Randomized parallel design, single group study conducted at clinical research organization of Ahmadabad.Results:
In all subjects time taken for maximum plasma concentration of fexofenadine (Tmax) was around 3 h and the value of average maximum plasma concentration was 460.63 ng/mL, the effect of fexofenadine on the heart (measured as QTc interval prolongation) was maximum (Emax) after 6 h and average QTc interval was 469.75 ms. Thus, the time to maximum concentration of fexofenadine did not match with the maximum effect on the heart as measured by QTc interval.Conclusion:
The relationship between the drug concentration and drug effect on the heart are at two different time scales. It can be understood by two-compartment model of pharmacokinetics, and this retardation or lagging of an effect behind the concentration is known as hysteresis. The increase of QTc was not beyond 500 ms and not sustained, demonstrating overall cardiac safety of fexofenadine. 相似文献10.
BACKGROUND AND PURPOSE
Halofantrine can cause a prolongation of the cardiac QT interval, leading to serious ventricular arrhythmias. Hyperlipidaemia elevates plasma concentration of halofantrine and may influence its tissue uptake. The present study examined the effect of experimental hyperlipidaemia on QT interval prolongation induced by halofantrine in rats.EXPERIMENTAL APPROACH
Normolipidaemic and hyperlipidaemic rats (induced with poloxamer 407) were given 4 doses of halofantrine (i.v., 4–40 mg·kg−1·d−1) or vehicle every 12 h. Under brief anaesthesia, ECGs were recorded before administration of the vehicle or drug and 12 h after the first and last doses. Blood samples were taken at the same time after the first and last dose of halofantrine. Hearts were also collected 12 h after the last dose. Plasma and heart samples were assayed for drug and desbutylhalofantrine using a stereospecific method.KEY RESULTS
In the vehicle group, hyperlipidaemia by itself did not affect the ECG. Compared to baseline, QT intervals were significantly higher in both normolipidaemic and hyperlipidaemic rats after halofantrine. In hyperlipidaemic rats, plasma but not heart concentrations of the halofantrine enantiomers were significantly higher compared to those in normolipidaemic rats. Despite the lack of difference in the concentrations of halofantrine in heart, QT intervals were significantly higher in hyperlipidaemic compared to those in normolipidaemic rats.CONCLUSIONS AND IMPLICATIONS
The unbound fraction of halofantrine appeared to be the controlling factor for drug uptake by the heart. Our data suggested a greater vulnerability to halofantrine-induced QT interval prolongation in the hyperlipidaemic state. 相似文献11.
Dixon R Job S Oliver R Tompson D Wright JG Maltby K Lorch U Taubel J 《British journal of clinical pharmacology》2008,66(3):396-404
AIM
To characterize the effects of lamotrigine on QT interval in healthy subjects.METHODS
Healthy subjects received a single oral dose of moxifloxacin (400 mg) or placebo in crossover design, followed by a dose-escalating regimen of lamotrigine (n = 76) over a 77-day period, or matched placebo (n = 76). Blood samples were taken for determination of moxifloxacin and lamotrigine concentrations and digital 12-lead ECGs were recorded. The relationships between individual QT values and respective individual moxifloxacin or lamotrigine concentrations were explored using population pharmacokinetic–pharmacodynamic (PK–PD) modelling.RESULTS
Moxifloxacin was associated with a maximum mean increase from baseline in QTcF of 14.81 ms [90% confidence interval (CI) 13.50, 16.11] 2.5 h after dosing. Steady-state exposure to lamotrigine (50, 150 or 200 mg b.d.) was not associated with an increase in QTc interval. Small reductions in QTcF (maximum mean difference from placebo −7.48 ms, 90% CI −10.49, −4.46) and small increases in heart rate (maximum mean difference from placebo 5.94 bpm, 90% CI 3.81, 8.06) were observed with lamotrigine 200 mg b.d. vs. placebo. No effect of lamotrigine on QRS duration or blood pressure was observed. No outliers with QTcF > 450 ms, or with an increase from baseline of >60 ms were observed in the lamotrigine group. PK–PD modelling indicated statistically significant decreases in individually corrected QT intervals for lamotrigine and statistically significant increases in individually corrected QT intervals for moxifloxacin over the concentration ranges studied.CONCLUSIONS
Therapeutic doses of lamotrigine (50–200 mg b.d.) were not associated with QT prolongation in healthy subjects.WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT
- Drugs that inhibit the human cardiac delayed rectifier potassium current may lead to prolongation of the cardiac QT interval and are associated with a fatal, polymorphic, ventricular tachycardia known as torsades de pointes.
- Lamotrigine is indicated in the treatment of epilepsy and the prevention of mood episodes in patients with bipolar disorder.
- Lamotrigine inhibits the human cardiac delayed rectifier potassium current in vitro, and it has been hypothesized that QT prolongation may contribute to the risk of sudden unexpected death in epilepsy patients.
WHAT THIS STUDY ADDS
- This is the first reported thorough QT/QTc study with lamotrigine conducted to International Conference on Harmonization guidelines.
- The mean QTc interval was not prolonged by lamotrigine in healthy subjects, as assessed by the standard heart rate correction methods (Fridericia''s and Bazett''s).
- The in vitro inhibition of the delayed rectifier potassium current does not translate into an effect on QT in man.
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Background:
Alerts generated by intravenous (IV) infusion pump safety software prevent life-threatening situations that might otherwise go unnoticed. However, when alerts are often clinically insignificant, health care workers may become desensitized and discount their importance, resulting in potentially dangerous situations. Little research has been devoted to visual alert desensitization.Method:
This paper describes how the Carolinas HealthCare System decreased the number of nonclinically relevant infusion pump alerts by analyzing alert data that were formatted into scatter plots. This in turn enabled the identification of the medications associated with the most meaningful alerts and those associated with the least meaningful alerts.Conclusion:
By revising drug library limits for specific medications, it was possible to decrease the number of less clinically meaningful alerts, reduce alert fatigue, and thereby increase the effectiveness of the smart infusion pumps. This added another layer of safety to patient care. 相似文献13.
Nejib Zemzemi Miguel O Bernabeu Javier Saiz Jonathan Cooper Pras Pathmanathan Gary R Mirams Joe Pitt-Francis Blanca Rodriguez 《British journal of pharmacology》2013,168(3):718-733
Background and Purpose
Understanding drug effects on the heart is key to safety pharmacology assessment and anti-arrhythmic therapy development. Here our goal is to demonstrate the ability of computational models to simulate the effect of drug action on the electrical activity of the heart, at the level of the ion-channel, cell, heart and ECG body surface potential.Experimental Approach
We use the state-of-the-art mathematical models governing the electrical activity of the heart. A drug model is introduced using an ion channel conductance block for the hERG and fast sodium channels, depending on the IC50 value and the drug dose. We simulate the ECG measurements at the body surface and compare biomarkers under different drug actions.Key Results
Introducing a 50% hERG-channel current block results in 8% prolongation of the APD90 and 6% QT interval prolongation, hERG block does not affect the QRS interval. Introducing 50% fast sodium current block prolongs the QRS and the QT intervals by 12% and 5% respectively, and delays activation times, whereas APD90 is not affected.Conclusions and Implications
Both potassium and sodium blocks prolong the QT interval, but the underlying mechanism is different: for potassium it is due to APD prolongation; while for sodium it is due to a reduction of electrical wave velocity. This study shows the applicability of in silico models for the investigation of drug effects on the heart, from the ion channel to the ECG-based biomarkers. 相似文献14.
Kim R. Saverno Daniel C. Malone John Kurowsky 《American journal of pharmaceutical education》2009,73(2)
Objective
To evaluate the ability of third- and fourth-year pharmacy students to identify clinically significant drug-drug interactions (DDIs)Methods
A questionnaire designed to measure DDI knowledge was disseminated to fourth-year pharmacy students in a school of pharmacy. A second questionnaire was distributed to third-year pharmacy students in 2 schools of pharmacy (schools A and B) and re-administered to students in 1 of the schools 1 year later.Results
Class of 2005 fourth-year pharmacy students correctly categorized an average of 52% ± 13% DDI pairs on the first questionnaire. Third-year pharmacy students at schools A and B correctly categorized an average of 61% ± 18% and 66% ± 15% of DDI pairs, respectively. The average percentage of correct responses for fourth-year students from the class of 2007 was 65% (± 17%).Conclusion
Pharmacy students'' ability to identify important DDIs is far from optimal, even after completing experiential requirements. 相似文献15.
Objectives
This study investigates opioid maintenance treatment (OMT) patients found to have corrected QT (QTc) interval above 500 ms, with particular focus on past medical history, genetic testing and cardiac investigations.Methods
Detailed medical and cardiac history was obtained, with particular focus upon risk factors. Cardiac investigations, including genetic testing for the five most common long QT syndrome (LQTS) mutations, exercise electrocardiography (ECG) and 24-h ECG recordings, were performed.Results
Of 200 OMT patients assessed with ECG, seven methadone maintained patients identified with QTc interval above 500 ms participated in this study. Two were identified as heterozygous LQTS mutation carriers. Both had experienced cardiac symptoms prior to and during OMT. No other risk factors for QTc prolongation were detected among the seven patients. Six of the seven patients underwent further cardiac investigations. QTc intervals fluctuated widely over 24 h and during exercise for all patients. Only one of the LQTS mutation carriers switched to buprenorphine and started on a beta-blocker. Despite strong medical advice and information, none of the other patients wanted to switch to buprenorphine or take other cardiac protective measures.Conclusion
Findings indicate the importance of recording a thorough past medical history, focusing specifically on previous cardiac symptoms, and on other known risk factors for QTc prolongation, prior to initiating patients on methadone. 相似文献16.
Marc Vandemeulebroecke Jürgen Lembcke Herbert Wiesinger Wolfgang Sittner & Stefanie Lindemann 《British journal of clinical pharmacology》2009,68(3):435-446
AIMS
Within the framework of the clinical development of BX471, this study was intended to provide experience in conducting ‘thorough QTc studies’ according to ICH E14. A broad range of QT correction methods and analysis strategies was employed.METHODS
A double-blind, placebo- and positive-controlled, single-centre, three-way cross-over study was conducted in 74 healthy volunteers. Electrocardiograms were read by blinded experts. QT correction methods included Bazett''s (QTcB), Fridericia''s (QTcF) and several regression-based corrections.RESULTS
There was a significant QTcF prolongation of 10.26 ms by the positive control compared with placebo [95% confidence interval (7.83, 12.70)]. BX471 at therapeutic doses did not cause substantial QTc prolongation [QTcF estimate 2.93 ms, 95% confidence interval (1.00, 4.86); QTcB estimate 3.30 ms, 95% confidence interval (0.85, 5.74)]. Regression-based QT correction methods yielded similar results to Fridericia''s correction [e.g. using a linear regression across the study population, QTc estimate 2.39 ms, 95% confidence interval (0.55, 4.23)]. Differences between the various regression-based correction methods were small. Results were not affected by whether the QT corrections were performed per ECG or per beat.CONCLUSIONS
BX471 does not cause meaningful QTc prolongation. Three QT correction methods may be sufficient in future studies: Bazett''s (required by regulatory authorities), Fridericia''s (as the most reliable fixed formula) and a regression-based correction (individually or population-based), each performed per ECG (i.e. applied to the means of several beats of one ECG recording). 相似文献17.
Benno Roesch Mary E. Corcoran Jennifer Fetterolf Mary Haffey Patrick Martin Peter Preston Jaideep Purkayastha Phillip Wang James Ermer 《Drugs in R&D》2013,13(2):119-128
Background
In clinical practice, α2-adrenoceptor agonists have been adjunctively administered with psychostimulants for the treatment of attention-deficit/hyperactivity disorder (ADHD). Two studies have examined the adjunctive use of guanfacine extended release (GXR, Intuniv®; Shire Development LLC, Wayne, PA, USA) with psychostimulants in children and adolescents with a suboptimal response to psychostimulant treatment. However, the potential for pharmacokinetic drug–drug interactions (DDIs) between GXR and lisdexamfetamine dimesylate (LDX, Vyvanse®; Shire US LLC, Wayne, PA, USA) has not been thoroughly evaluated.Objective
The primary objective of this study was to examine the pharmacokinetics of GXR 4 mg and LDX 50 mg given as single doses alone and in combination.Study Design
This was an open-label, randomized, three-period crossover, DDI study.Setting
The study was conducted in a single clinical research center.Participants
Forty-two healthy adults were randomized in this study.Interventions
Subjects were administered single oral doses of GXR 4 mg, LDX 50 mg, or GXR and LDX in combination.Main Outcome Measures
Blood samples collected predose and up to 72 h postdose assessed guanfacine, LDX, and d-amphetamine levels. Bioequivalence was defined as the 90 % confidence intervals (CIs) of the geometric mean ratios of the area under the plasma concentration–time curve extrapolated to infinity (AUC0–∞) and maximum plasma concentration (Cmax) falling within the bioequivalence reference interval (0.80–1.25). Safety measures included adverse events, vital signs, and electrocardiograms (ECGs).Results
Forty subjects completed the study. Following administration of LDX alone or in combination with GXR, the statistical comparisons of the AUC0–∞ and Cmax of d-amphetamine fell entirely within the reference interval. For guanfacine, the 90 % CI of the geometric mean ratio of AUC∞ for the two treatments was within the bioequivalence criteria, but for Cmax the upper bound of the 90 % CI exceeded the standard range for bioequivalence by 7 %. This relatively small change is unlikely to be clinically meaningful. Treatment-emergent adverse events (TEAEs) were reported by 42.9 % of subjects; the most commonly reported TEAEs included dizziness (5.0, 7.3, and 7.3 %) and headache (7.5, 4.9, and 7.3 %) following administration of GXR, LDX, and GXR and LDX in combination, respectively. Clinically significant ECG abnormalities occurred in one subject following administration of LDX and in one subject following coadministration of GXR and LDX.Conclusions
In healthy adults, coadministration of GXR and LDX did not result in a clinically meaningful pharmacokinetic DDI compared with either treatment alone. No unique TEAEs were observed with coadministration of GXR and LDX compared with either treatment alone. 相似文献18.
Sugiyama A Nakamura Y Nishimura S Adachi-Akahane S Kumagai Y Gayed J Naseem A Ferber G Taubel J Camm J 《British journal of clinical pharmacology》2012,73(3):455-459
AIMS
There is no consensus as to what extent the results of thorough QT interval/corrected QT interval (QT/QTc) studies need to be bridged.METHODS
The results of two studies using levofloxacin in Japanese and Caucasian subjects were compared in a post hoc analysis to investigate the similarity of dose–effect responses.RESULTS
Concentration–response analysis based on the change of QT interval corrected using Fridericia''s formula (QTcF) from time-matched placebo was planned and performed in the combined data sets. At the geometric maximum mean concentration for the two doses in the Caucasian study, a predicted effect on QTcF comparable to the effects observed was found. For the Japanese study, the predicted effect was lower, but the difference was not statistically significant.CONCLUSIONS
No statistically significant differences in QTc-prolonging effect between Japanese and Caucasian subjects were observed following levofloxacin dosing. However, a trend suggests that Caucasian subjects may be more sensitive. Age and sex did not have an impact. 相似文献19.
Attila S Farkas Péter Makra Norbert Csík Szabolcs Orosz Michael J Shattock Ferenc Fül?p Tamás Forster Miklós Csanády Julius Gy Papp András Varró András Farkas 《British journal of pharmacology》2009,156(6):920-932
Background and purpose:
The Na+/Ca2+ exchanger (NCX) may contribute to triggered activity and transmural dispersion of repolarization, which are substrates of torsades de pointes (TdP) type arrhythmias. This study examined the effects of selective inhibition of the NCX by SEA0400 on the occurrence of dofetilide-induced TdP.Experimental approach:
Effects of SEA0400 (1 µmol·L−1) on dofetilide-induced TdP was studied in isolated, Langendorff-perfused, atrioventricular (AV)-blocked rabbit hearts. To verify the relevance of the model, lidocaine (30 µmol·L−1) and verapamil (750 nmol·L−1) were also tested against dofetilide-induced TdP.Key results:
Acute AV block caused a chaotic idioventricular rhythm and strikingly increased beat-to-beat variability of the RR and QT intervals. SEA0400 exaggerated the dofetilide-induced increase in the heart rate-corrected QT interval (QTc) and did not reduce the incidence of dofetilide-induced TdP [100% in the SEA0400 + dofetilide group vs. 75% in the dofetilide (100 nmol·L−1) control]. In the second set of experiments, verapamil further increased the dofetilide-induced QTc prolongation and neither verapamil nor lidocaine reduced the dofetilide-induced increase in the beat-to-beat variability of the QT interval. However, lidocaine decreased and verapamil prevented the development of dofetilide-induced TdP as compared with the dofetilide control (TdP incidence: 13%, 0% and 88% respectively).Conclusions and implications:
Na+/Ca2+ exchanger does not contribute to dofetilide-induced TdP, whereas Na+ and Ca2+ channel activity is involved in TdP genesis in isolated, AV-blocked rabbit hearts. Neither QTc prolongation nor an increase in the beat-to-beat variability of the QT interval is a sufficient prerequisite of TdP genesis in rabbit hearts. 相似文献20.