3,4-diaminopyridine base effectively treats the weakness of Lambert-Eaton myasthenia.

INTRODUCTION: 3,4-diaminopyridine has been used to treat Lambert-Eaton myasthenia (LEM) for 30 years despite the lack of conclusive evidence of efficacy. METHODS: We conducted a randomized double-blind placebo-controlled withdrawal study in patients with LEM who had been on stable regimens of 3,4-diaminopyridine base (3,4-DAP) for ≥ 3 months. The primary efficacy endpoint was >30% deterioration in triple timed up-and-go (3TUG) times during tapered drug withdrawal. The secondary endpoint was self-assessment of LEM-related weakness (W-SAS). RESULTS: Thirty-two participants were randomized to continuous 3,4-DAP or placebo groups. None of the 14 participants who received continuous 3,4-DAP had > 30% deterioration in 3TUG time versus 72% of the 18 who tapered to placebo (P < 0.0001). W-SAS similarly demonstrated an advantage for continuous treatment over placebo (P < 0.0001). Requirement for rescue and adverse events were more common in the placebo group. DISCUSSION: This trial provides significant evidence of efficacy of 3,4-DAP in the maintenance of strength in LEM. Muscle Nerve 57: 561-568, 2018.

Thorough QT/QTc Study Evaluating the Effect of Macimorelin on Cardiac Safety Parameters in Healthy Participants.

Macimorelin is an orally active growth hormone secretagogue indicated for the diagnosis of adult growth hormone deficiency. The primary objective of this study was to evaluate the effect of macimorelin on the baseline and placebo-corrected mean QT interval using Fridericia's formula (ΔΔQTcF). Secondary objectives were to determine QTcF for moxifloxacin; evaluate the effects of macimorelin on other cardiac intervals (PR, QRS, RR), heart rate, and electrocardiogram morphology parameters; characterize pharmacokinetics; and assess safety of macimorelin. The phase 1 thorough QT/QTc study, designed according to the International Council for Harmonisation E14 guideline, was a randomized, placebo-controlled, double-blind, 3-way complete crossover study comparing the effect of macimorelin 2.0 mg/kg with placebo and moxifloxacin 400 mg (positive control). Data were collected over a 3-month span from male (n=36) and female participants (n=24) aged 18 to 55 years with body mass index between 18.5 and 30.0 kg/m2 . Fifty-six participants received all 3 treatments. The ΔΔQTcF for macimorelin showed a prolongation with a maximum mean value of 9.61 milliseconds (2-sided 90% confidence interval, 7.81 milliseconds and 11.41 milliseconds) at 4 hours after dosing. The 2-sided 90% confidence interval of this value also exceeded the 10 millisecond threshold at 3 hours after dosing. Assay sensitivity was confirmed with moxifloxacin. Other electrocardiogram parameters evaluated were not influenced by macimorelin. Macimorelin did not raise other safety concerns and was well tolerated. In summary, a single supratherapeutic dose of macimorelin prolonged cardiac repolarization according to the regulatory guideline.

Heart rate variability increases with reductions in cigarette smoke exposure after 3 days.

BACKGROUND: Smoking has been shown to influence the tone of the autonomic nervous system as reflected by heart rate variability (HRV). To date, no information is available as to whether 24-hour HRV might differentiate users of different tobacco products. OBJECTIVE: To assess the differences in HRV derived from the 24-hour electrocardiogram (ECG) following the use of 2 tobacco products of potentially different exposures. METHODS: Thirty adult Caucasian male smokers (mean age: 42.8 + 5.7 years) smoking 20 to 40 cigarettes/ day were randomized in a 3-way crossover study design to either smoke a conventional cigarette (CC, tar: 11 mg, Nic: 0.8 mg), to use the Electrically Heated Cigarette Smoking System (EHCSS: tar: 5 mg, Nic: 0.3 mg, according to the Federal Trade Commission [FTC]), or to stop smoking (NS) for 3 days each. The 24 hours ECGs were recorded during the last 24 hours of each exposure period. RESULTS: A 24-hour ECG showed highest mean values for standard deviation of all normal-to-normal heart beat (NN) intervals (SDNN), standard deviation of all 5-minute averaged NN intervals in a 24-hour period (SDANN), mean of the standard deviations of the NN intervals calculated from all 5-minute segments in a 24-hour period (SDNNI), percentage (P) of all NN intervals that differ by 50 milliseconds of all NN (PNN50%), the square root of the mean of all squared differences between adjacent NN intervals in 24-hour period (RMSSD), and total number of all NN intervals divided by the height of the histogram of all NN intervals measured on a discrete scale with bins of 7 x 8125 ms (1/128 seconds; HRVTI) when participants stopped smoking followed by the use of the reduced exposure product and CC. CONCLUSION: Heart rate variability tended to increase with reduced smoke exposure.

No QTc Prolongation with Semaglutide: A Thorough QT Study in Healthy Subjects.

INTRODUCTION: Semaglutide is a glucagon-like peptide-1 (GLP-1) analog approved for the once-weekly treatment of type 2 diabetes. The objective of this 16-week, double-blind, single-center thorough QT study was to confirm that semaglutide treatment does not prolong cardiac repolarization versus placebo. Prolongation of the QT interval is a biomarker for ventricular tachyarrhythmia. METHODS: In a parallel design, 168 healthy subjects were randomized to the treatment or placebo arms, of whom 166 were treated with subcutaneous semaglutide (N = 83; escalated to a supratherapeutic dose of 1.5 mg) or placebo (N = 83). The subjects (60% males) had a mean age of 38.2 years and body mass index of 25.1 kg/m2. To assess QT assay sensitivity, subjects in the placebo group received a single 400 mg moxifloxacin dose as positive control, and placebo in a crossover fashion. The primary endpoint was the time-matched change from baseline in QT interval corrected individually for heart rate (ΔQTcI), calculated from 11 electrocardiogram recordings from 0 to 48 h after the last 1.5 mg dose. Similar assessments were made for the therapeutic 0.5 and 1.0 mg semaglutide dose levels. RESULTS: No QTcI prolongation occurred with any semaglutide dose; the upper limits of two-sided 90% confidence intervals of the placebo-subtracted ΔQTcI were < 10 ms at all doses and time points. Exposure-response analysis showed no dependence of QTcI on semaglutide concentration. QT assay sensitivity was confirmed. The semaglutide safety profile was similar to that of other GLP-1 receptor agonists. CONCLUSION: Based on investigations of QT/QTc, no concern with regard to ventricular arrhythmias was raised as semaglutide did not prolong the cardiac repolarization duration in healthy subjects. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT 02064348. FUNDING: Novo Nordisk.

A randomized, double-blind, placebo-controlled study of the safety and efficacy of intravenous MCC-135 as an adjunct to primary percutaneous coronary intervention in patients with acute myocardial infarction: rationale and design of the evaluation of MCC-135 for left ventricular salvage in acute MI (EVOLVE) study.

As a consequence of acute ischemia and reperfusion in patients with acute ST elevation myocardial infarction, calcium overload inside myocytes not only affects myocardial contraction, relaxation, and myocyte recovery following reperfusion, but also may be related to myocyte necrosis and fatal arrhythmia. MCC-135 is the first in a new class of agents that reduce intracellular calcium overload. Pre-clinical and early clinical studies yielded promising results for patients with ST elevation myocardial infarction. The Evaluation of MCC-135 for Left Ventricular Salvage in Acute MI (EVOLVE) study is a Phase 2a, multicenter, randomized, double-blind, placebo-controlled clinical trial of 2 new doses of MCC-135 (4.5 mg/kg/48 hours and 9.0 mg/kg/48 hours) as adjunct therapy for preservation of left ventricular function and reduction of infarct size in patients undergoing primary percutaneous coronary intervention (PCI) for electrocardiographically moderate-large ST elevation myocardial infarction. The primary endpoint will be left ventricular ejection fraction on Day 5 post myocardial infarction as determined by single photon emission computed tomography (SPECT). Secondary endpoints will include SPECT and echocardiographic assessments, serum cardiac markers, clinical outcomes, and safety measures at specific time points through Day 30 post myocardial infarction. Follow-up clinical and safety assessments will be continued until Day 180. The rationale, design, and methods of the EVOLVE study are described in this paper, along with 2 sub-studies, involving a comparison of pre- and post-PCI measurements with either SPECT or echocardiography, to examine myocardial salvage and the time course of changes in myocardial infarction size and left ventricular function. MINIABSTRACT: The Evaluation of MCC-135 for Left Ventricular Salvage in Acute MI (EVOLVE) study is a Phase 2, multicenter, randomized, double-blind, placebo-controlled clinical trial of two doses of MCC-135, first in a new class of agents that reduce intracellular calcium overload, as adjunct therapy for preservation of left ventricular function and reduction of infarct size in patients with moderate-large STEMI undergoing primary PCI. The rationale, design, and methods of the EVOLVE study, along with two sub-studies, are described in this paper.