Mechanism of cardiac arrhythmias induced by epinephrine in dogs with hypokalemia

To investigate the mechanism of ventricular arrhythmias induced by epinephrine in dogs with hypokalemia, 30 adult mongrel dogs were separated into a control group (n = 13) and a hypokalemia group (n = 17). In the hypokalemia group, sodium polystyrene sulfonate (5 g/kg body weight) was infused into the colon. In both groups, the serum concentrations of sodium, potassium and calcium were measured every 15 minutes for 60 minutes. The mean ( ± standard deviation) serum potassium level of the hypokalemia group decreased significantly from 3.81 ± 0.21 to 2.92 ± 0.36 mEq/liter; there were no significant changes in other electrolytes. After 60 minutes, epinephrine (10 μg/kg) was injected intravenously in the hypokalemia and control groups, and the arrhythmia ratio (the number of ventricular ectopic beats divided by the total heart rate) was calculated for 5 minutes. Each group was further classified into subgroups of dogs with an arrhythmia ratio higher or lower than 10%. An arrhythmia ratio over 10% was observed in 7.7% of the control group and 53% of the hypokalemia group.Immediately after 5 minutes of epinephrine injection, myocardial mitochondria and plasma membrane fraction were prepared from each group. Mitochondrial calcium content and phospholipase activity of plasma membrane fraction were determined. Significant increases in both mitochondrial calcium content and phospholipase activity were observed in the dogs with hypokalemia and an arrhythmia ratio greater than 10%. In the hypokalemia group, there was a clear reciprocal correlation (r = − 0.79) between serum potassium concentration at 60 minutes and mitochondrial calcium content, and a clear correlation (r = 0.80) between mitochondrial calcium content and phospholipase activity. It was also demonstrated that the dogs with a higher than 10% arrhythmia ratio had a low serum potassium concentration, high mitochondrial calcium content and high phospholipase activity. These results suggest that hypokalemia enhances the calcium influx induced by epinephrine, resulting in activation of phospholipase, which is responsible for the development of ventricular arrhythmias

Sitagliptin and Carotid Atherosclerosis in Type 2 Diabetes

Background Experimental studies have suggested that dipeptidyl peptidase-4 (DPP-4) inhibitors provide cardiovascular protective effects. We performed a randomized study to evaluate the effects of sitagliptin added on to the conventional therapy compared with conventional therapy alone (diet, exercise, and/or drugs, except for incretin-related agents) on the intima-media thickness (IMT) of the carotid artery, a surrogate marker for the evaluation of atherosclerotic cardiovascular disease, in people with type 2 diabetes mellitus (T2DM). Methods and Findings We used a multicenter PROBE (prospective, randomized, open label, blinded endpoint) design. Individuals aged ≥30 y with T2DM (6.2% ≤ HbA1c < 9.4%) were randomly allocated to receive either sitagliptin (25 to 100 mg/d) or conventional therapy. Carotid ultrasound was performed at participating medical centers, and all parameters were measured in a core laboratory. Of the 463 enrolled participants with T2DM, 442 were included in the primary analysis (sitagliptin group, 222; conventional therapy group, 220). Estimated mean (± standard error) common carotid artery IMT at 24 mo of follow-up in the sitagliptin and conventional therapy groups was 0.827 ± 0.007 mm and 0.837 ± 0.007 mm, respectively, with a mean difference of −0.009 mm (97.2% CI −0.028 to 0.011, p = 0.309). HbA1c level at 24 mo was significantly lower with sitagliptin than with conventional therapy (6.56% ± 0.05% versus 6.72%± 0.05%, p = 0.008; group mean difference −0.159, 95% CI −0.278 to −0.041). Episodes of serious hypoglycemia were recorded only in the conventional therapy group, and the rate of other adverse events was not different between the two groups. As it was not a placebo-controlled trial and carotid IMT was measured as a surrogate marker of atherosclerosis, there were some limitations of interpretation. Conclusions In the PROLOGUE study, there was no evidence that treatment with sitagliptin had an additional effect on the progression of carotid IMT in participants with T2DM beyond that achieved with conventional treatment

Long-term effects of tolvaptan in patients requiring recurrent hospitalization for heart failure

Although reports suggest that tolvaptan does not reduce survival or subsequent hospitalization rates in heart failure patients, its continuous use has shown good outcomes in some patients who cannot be effectively managed with high doses of loop diuretics. Therefore, we investigated the association of patient characteristics and continued tolvaptan use in heart failure patients with changes in the frequency and annual duration of patient hospitalization due to heart failure. We carefully reviewed the medical records of patients hospitalized due to heart failure who began tolvaptan therapy and continued with outpatient treatment between December 2010 and November 2013 (tolvaptan group); patients hospitalized for heart failure between May 2008 and March 2009 served as controls. We set the reference dates as the start of tolvaptan therapy (tolvaptan group) or as the date of admission (control group). The changes in hospitalization frequency and total hospitalization time due to heart failure, before and after the reference dates, were not significantly different between the tolvaptan and control groups. In the tolvaptan group, a high estimated glomerular filtration rate was a predictor of decreased hospitalization. Continuous tolvaptan use did not decrease hospitalization duration in all heart failure patients, but good renal function was predictive of a good response

Additional file 1 of Impact of HIF prolyl hydroxylase inhibitors in heart failure patients with renal anemia

Additional file 1. Receiver operating characteristic curve for (Figure S1) ferritin level at baseline and (Figure S2) TSAT value at 1 month after the start of HIF-PH inhibitor treatment

Influence of proton pump inhibitors on blood dabigatran concentrations in Japanese patients with non-valvular atrial fibrillation

Background: Dabigatran is a direct thrombin inhibitor used to decrease the risk of ischemic stroke in patients with non-valvular atrial fibrillation (NVAF). Its prodrug, dabigatran etexilate (DE) is often co-administrated with a proton pump inhibitor (PPI) because of its adverse effects on the gastrointestinal tract. Drug-drug interactions between DE and PPIs in daily clinical practice have not been fully elucidated. Methods: Changes in blood dabigatran concentration (DC) were investigated using the dilute thrombin time test in a randomized, open-label, two-period crossover study including 34 Japanese patients with NVAF receiving dabigatran therapy with or without PPI. Results: The average trough DC was significantly higher without PPI than with PPI (83 ± 42.3 vs. 55.5 ± 24.6 ng/mL, respectively; P < 0.001). Similarly, the average peak DC was significantly higher without PPI than with PPI (184.1 ± 107.7 vs. 124 ± 59.2 ng/mL, respectively; P = 0.0029). The average ratio of DC change at the trough and peak levels did not differ significantly among the three PPI types. Conclusions: PPI administration significantly decreased the trough and peak DCs in patients with NVAF. Therefore, when prescribing PPIs for patients with NVAF in a clinical setting, the possibility that the bioavailability of dabigatran may decrease should be considered. Keywords: Dabigatran, Proton pump inhibitor, Drugâdrug interactio