Evaluation of chronic toxicity of cyclocreatine in beagle dogs after oral gavage administration for up to 23 weeks.

Cyclocreatine (LUM-001) was evaluated for chronic toxicity (23 weeks) in beagle dogs to support clinical development in patients with creatine transporter deficiency (CTD) disorder. Deionized water (vehicle control) or cyclocreatine was administered by oral gavage twice daily (12 ± 1 h apart) at 20, 40 and 75 mg/kg/dose followed by a recovery period. Due to severe toxicity, the study was terminated earlier than the planned 39 weeks of dosing. Animals in the 20, 40 and 75 mg/kg/dose groups completed 160, 106, and 55 days of dosing, respectively, followed by 30, 55 and 106 days of a recovery period, respectively. Three (25%), 7 (58%), and 7 (58%) animals were euthanized and/or found dead in the 40, 80, and 150 mg/kg/day dose groups, respectively. Clinical signs observed were inappetence, frequent emesis, stool abnormalities, weight loss, lethargy and respiratory distress. Histopathological evaluation revealed congestion, edema, cellular infiltration, fibrin, and/or hemorrhage in the lungs of all dose groups. Additionally, animals in all cyclocreatine treatment groups had perinuclear cytoplasmic vacuoles in the heart, kidneys, skeletal and smooth muscles. After the recovery period, the vacuoles were still observed in the cardiac and renal tissues. Cyclocreatine was absorbed rapidly with mean Tmax within 1 to 2 h and half-life ranged between 2.17 and 2.79 h on Day 1, however, on the final day of dosing, it ranged between 5.80 and 8.77 h (males) and 10.3 to 13.1 h (females). To conclude, in this study the lungs, kidneys, heart, skeletal and smooth muscles were identified as the target organs of cyclocreatine toxicity in beagle dogs.

Cyclocreatine Transport by SLC6A8, the Creatine Transporter, in HEK293 Cells, a Human Blood-Brain Barrier Model Cell, and CCDSs Patient-Derived Fibroblasts.

PURPOSE: Cyclocreatine, a creatine analog, is a candidate drug for treating patients with cerebral creatine deficiency syndromes (CCDSs) caused by creatine transporter (CRT, SLC6A8) deficiency, which reduces brain creatine level. The purpose of this study was to clarify the characteristics of cyclocreatine transport in HEK293 cells, which highly express endogenous CRT, in hCMEC/D3 cells, a human blood-brain barrier (BBB) model, and in CCDSs patient-derived fibroblasts with CRT mutations. METHODS: Cells were incubated at 37°C with [14C]cyclocreatine (9 µM) and [14C]creatine (9 µM) for specified periods of times in the presence or absence of inhibitors, while the siRNAs were transfected by lipofection. Protein expression and mRNA expression were quantified using targeted proteomics and quantitative PCR, respectively. RESULTS: [14C]Cyclocreatine was taken up by HEK293 cells in a time-dependent manner, while exhibiting saturable kinetics. The inhibition and siRNA knockdown studies demonstrated that the uptake of [14C]cyclocreatine by both HEK293 and hCMEC/D3 cells was mediated predominantly by CRT as well as [14C]creatine. In addition, uptake of [14C]cyclocreatine and [14C]creatine by the CCDSs patient-derived fibroblasts was found to be largely reduced. CONCLUSION: The present study suggests that cyclocreatine is a CRT substrate, where CRT is the predominant contributor to influx of cyclocreatine into the brain at the BBB. Our findings provide vital insights for the purposes of treating CCDSs patients using cyclocreatine.

Creatinine monitoring patterns in the setting of direct oral anticoagulant therapy for non-valvular atrial fibrillation.

Guidelines and experts note that patients with atrial fibrillation require regular renal function monitoring to ensure safe use of direct oral anticoagulants (DOACs). Insufficient monitoring could lead to inappropriate dosing and adverse events. Our objective was to describe the frequency of insufficient creatinine monitoring among patients on DOACs, and to describe clinical factors associated with insufficient monitoring. We hypothesized that renal impairment would be associated with insufficient monitoring. A retrospective cohort study was performed with data from the Michigan Anticoagulant Quality Improvement Initiative. Patients were included if they initiated DOAC therapy for stroke prevention related to atrial fibrillation, remained on therapy for ≥ 1 year, and had baseline creatinine and weight measurements. Creatinine clearance (CrCl) was calculated via Cockcroft-Gault equation. Our outcome was the presence of insufficient creatinine monitoring, defined as: < 1 creatinine level/year for patients with CrCl > 50, or < 2 creatinine levels/year for patients with CrCl ≤ 50. Multivariable analysis was done via logistic regression. Study population included 511 patients. In overall, 14.0% of patients received insufficient monitoring. Among patients with CrCl > 50, 11.5% had < 1 creatinine level/year. Among patients with CrCl ≤ 50, 27.1% received < 2 creatinine levels/year. Baseline renal dysfunction was associated with a higher likelihood of insufficient creatinine monitoring (adjusted odds ratio 3.64, 95% confidence interval 1.81-7.29). This shows a significant gap in the monitoring of patients on DOACs-patients with renal impairment are already at higher risk for adverse events. Future studies are needed to describe the barriers in monitoring these patients and to identify how to optimally address them.

Simultaneous quantitative analysis of phosphocreatine, creatine and creatinine in plasma of children by HPLC-MS/MS method: Application to a pharmacokinetic study in children with viral myocarditis.

A simple and rapid HPLC-MS/MS method was developed and validated for simultaneous measurement of phosphocreatine and its metabolites creatine and creatinine in children's plasma. A 50 µL aliquot of plasma was prepared by protein precipitation with acetonitrile-water (1000 µL, 1:1, v/v) followed by separation on a Hypersil Gold C18 column (35°C) with gradient mobile phase consisting of 2 mm ammonium acetate aqueous solution (pH 10) and methanol at a flow rate of 0.3 mL/min and analyzed by mass spectrometry in both positive (phosphocreatine) and negative (creatine and creatinine) ion multiple reaction monitoring mode. Good linearity (r > 0.99) was obtained for the three analytes. The intra-day and inter-day values of CV were <5.46% (-13.09% ≤ RE ≤ 2.57%). The average recoveries of the three analytes were 70.9-97.5%. No obvious impact was found for the quantitation of three analytes in normal, hemolyzed and hyperlipemic plasma. In the end, this method was successfully applied to a pharmacokinetic study of phosphocreatine in children (six cases) with viral myocarditis of children after intravenous infusion of 2 g of the test drug. The pharmacokinetc parameters of phosphocreatine/creatine were as follows: t1/2 0.24/0.83 h, Tmax 0.49/0.55 h, Cmax 47.34/59.29 µg/mL, AUClast 17.07/59.63 h µg/mL, AUCinf 17.16/79.01 h µg/mL and MRT 0.29/0.67 h.

Quantification of vascular damage in acute kidney injury with fluorine magnetic resonance imaging and spectroscopy.

PURPOSE: To design a fluorine MRI/MR spectroscopy approach to quantify renal vascular damage after ischemia-reperfusion injury, and the therapeutic response to antithrombin nanoparticles (NPs) to protect kidney function. METHODS: A total of 53 rats underwent 45 min of bilateral renal artery occlusion and were treated at reperfusion with either plain perfluorocarbon NPs or NPs functionalized with a direct thrombin inhibitor (PPACK:phenyalanine-proline-arginine-chloromethylketone). Three hours after reperfusion, kidneys underwent ex vivo fluorine MRI/MR spectroscopy at 4.7 T to quantify the extent and volume of trapped NPs, as an index of vascular damage and ischemia-reperfusion injury. Microscopic evaluation of structural damage and NP trapping in non-reperfused renal segments was performed. Serum creatinine was quantified serially over 7 days. RESULTS: The damaged renal cortico-medullary junction trapped a significant volume of NPs (P = 0.04), which correlated linearly (r = 0.64) with the severity of kidney injury 3 h after reperfusion. Despite global large vessel reperfusion, non-reperfusion in medullary peritubular capillaries was confirmed by MRI and microscopy, indicative of continuing hypoxia due to vascular compromise. Treatment of animals with PPACK NPs after acute kidney injury did not accelerate kidney functional recovery. CONCLUSIONS: Quantification of ischemia-reperfusion injury after acute kidney injury with fluorine MRI/MR spectroscopy of perfluorocarbon NPs objectively depicts the extent and severity of vascular injury and its linear relationship to renal dysfunction. The lack of kidney function improvement after early posttreatment thrombin inhibition confirms the rapid onset of ischemia-reperfusion injury as a consequence of vascular damage and non-reperfusion. The prolongation of medullary ischemia renders cortico-medullary tubular structures susceptible to continued necrosis despite restoration of large vessel flow, which suggests limitations to acute interventions after acute kidney injury, designed to interdict renal tubular damage. Magn Reson Med 79:3144-3153, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Direct-acting oral anticoagulant drug level monitoring in clinical patient management.

The role of drug-level monitoring among patients using direct-acting oral anticoagulant (DOAC) is unclear. We aimed to investigate its 'real-life' utilization and effect on clinical management. A review of records of patients who underwent DOAC level testing during 2013-2017. Overall, 212 patients (median age 77 years) underwent 292 DOAC measurements [apixaban (n = 147), rivaroxaban (n = 102), dabigatran (n = 43)]. Monitoring volume increased by 460% during study period. DOAC level testing was performed during routine follow-up in 51 (17.5%) cases, whereas the remaining 241 (82.5%) measurements were performed due to selected clinical circumstances, most commonly: bleeding (n = 60), perioperative status (n = 45), breakthrough thrombosis (n = 37) and renal failure (n = 35). Drug levels were within the expected range in 210 (71.9%), above the expected range in 62 (21.2%) and lower than expected range in 20 (6.8%). In multivariate analysis, older age (P = 0.005), lower glomerular filtration rate (P = 0.001) and lower body mass index (P = 0.006) were associated with DOAC levels above the expected range. Clinical decisions were affected by DOAC monitoring following most (140/241, 58.1%) measurements for which we identified an indication for testing; yet only rarely when monitoring was performed during routine follow-up (7.8%, 4/51) (P < 0.0001). While no benefit of routine DOAC monitoring was observed, drug level measurement has an important role in the management of patients in selected circumstances. Age, body weight and creatinine clearance were found to be significant predictors of drug levels. Future studies are warranted to establish associations between drug levels and outcomes, and better delineate the role of DOAC monitoring.

Renal clearance and urinary excretion of omeprazole in healthy female volunteers in Pakistan.

Omeprazole is a widely prescribed proton pump inhibitor to treat various gastric acid hyper secretion disorders. The present study was designed to evaluate the renal clearance and urinary excretion of omeprazole in eight healthy female volunteers to increase the understanding of the contributing factors such as demographics variability in the renal clearance and urinary excretion of omeprazole under indigenous conditions. The urine and blood samples were collected 0.5, 1, 1.5, 2, 3, 4, 6, 8 hours after oral administration of enteric coated omeprazole (20 mg) and drug concentration in the samples was determined by High Performance Liquid Chromatography (HPLC) with C18 column and UV detector. Urinary excretion and renal clearance of omeprazole was calculated and data was statistically analyzed by using regression/correlation technique. Endogenous creatinine was also measured by reagent kit available in the market. The results indicate that mean diuresis was 0.0172±0.0029 ml/min/kg. While the mean values of renal clearance of creatinine and omeprazole were 1.315±0.103 and 0.066±0.0042 ml/min. kg, respectively. Whereas, clearance ratio was 0.055±0.007 which indicates back diffusion. The cumulative percentage of dose excreted was 6.71±0.358. A significant (p<0.05) negative correlation (r= -0.457) between clearance ratio and urine pH of omeprazole reflecting glomerular filtration reabsorption of drug at kidney tubular level while significant (p<0.05) negative correlation (r= -0.681) between clearance ratio and plasma concentration of omeprazole indicates the involvement of active tubular secretion of drug. It can be concluded that during glomerular filtration, omeprazole diffuse back/reabsorption. Therefore, Urinary excretion of omeprazole in indigenous healthy female subjects was observed to be lower than given in the literature values.

Estimation of Glomerular Filtration Rate in Patients With Cirrhosis by Using New and Conventional Filtration Markers and Dimethylarginines.

BACKGROUND & AIMS: Equations used to estimate glomerular filtration rate (GFR) are not accurate in patients with cirrhosis. We aimed to develop a new equation to estimate the GFR in subjects with cirrhosis and compare its performance with chronic kidney disease epidemiology collaboration (CKD-EPI) cystatin C and creatinine-cystatin C equations, which were derived in populations without cirrhosis. METHODS: From 2010 through 2014, we measured GFR in 103 subjects with cirrhosis based on non-radiolabeled iothalamate plasma clearance. We measured blood levels of creatinine, cystatin C, ß-trace protein, ß2-microglobulin, L-arginine, and symmetric and asymmetric dimethylarginines simultaneously with GFR. Multivariate linear regression analysis was performed to develop models to estimate GFR. Overall accuracy, defined by the root mean square error (RMSE) of our newly developed model to estimate GFR, was compared with that of the CKD-EPI equations. To obtain an unbiased estimate of our new equation to estimate GFR, we used a leave-one-out cross-validation strategy. RESULTS: After we considered all the candidate variables and blood markers of GFR, the most accurate equation we identified to estimate GFR included serum levels of creatinine and cystatin C, as well as patients' age, sex, and race. Overall, the accuracy of this equation (RMSE = 22.92) was superior to that of the CKD-EPI cystatin C equation (RMSE = 27.27, P = .004). Among subjects with cirrhosis and diuretic-refractory ascites, the accuracy of the equation we developed to estimate GFR (RMSE = 19.36) was greater than that of the CKD-EPI cystatin C (RMSE = 27.30, P = .003) and CKD-EPI creatinine-cystatin C equations (RMSE = 23.37, P = .004). CONCLUSIONS: We developed an equation that estimates GFR in subjects with cirrhosis and diuretic-refractory ascites with greater accuracy than the CKD-EPI cystatin C equation or CKD-EPI creatinine-cystatin C equation.

Pharmacokinetics of zanamivir following intravenous administration to subjects with and without renal impairment.

Intravenous zanamivir is in clinical development for the treatment of influenza in hospitalized patients, many of whom have renal impairment. This open-label study evaluated zanamivir pharmacokinetics and clinical safety following a single 100-mg intravenous infusion dose in subjects with impaired renal function compared with normal renal function. Male and female subjects between 18 and 79 years of age were recruited, four subjects to each renal function group (normal function and mild, moderate, and severe impairment). Serial blood samples were collected up to 24 h after dose administration (48 h for the severe renal impairment group) to estimate zanamivir serum pharmacokinetic parameters. Urine was collected over the same 24-h (or 48-h) period for estimation of renal clearance (CLR). Zanamivir pharmacokinetics were assessed by regression analysis of systemic clearance (CL) and CLR as a function of creatinine clearance (CLCR). Safety evaluations included adverse-event monitoring, vital signs, electrocardiogram, and clinical laboratory assessments. Zanamivir clearance (total and renal) significantly decreased with decreasing renal function, with corresponding increases in area under the concentration-time curve and elimination half-life. Renal impairment had no apparent effects on peak concentration or volume of distribution. Regression analysis indicated that zanamivir clearance was highly correlated (r(2) = 0.89) with creatinine clearance: CL ≅ 7.08 + 0.826 · CLCR. There were no patterns or trends in adverse events, and no new safety concerns were identified following administration of intravenous zanamivir. Results from this study support the inclusion of subjects with renal impairment, with appropriate dose adjustment, in studies to evaluate intravenous zanamivir in the treatment of influenza.

First-trimester Down syndrome screening in renal-transplanted pregnant women: a model for adjusting the false-positives rates.

OBJECTIVE: This study aimed to develop a model to adjust the increased ß-hCG levels observed in renal-transplanted women, leading to increased false-positive rates in Down syndrome screening. METHODS: Detailed data from 11 renal-transplanted and a nested-cohort of 70 pregnant women, matched by age, parity and gestational age were retrieved from our hospital records. Patient's age, multiples of the median (MoM) values for freeß-hCG, pregnancy-associated plasma protein-A, nuchal translucency, and creatinine concentration and clearance were noted. Freeß-hCG levels were adjusted according to the deviation of serum creatinine concentration by means of three different methods (median, proportionality and regression). Subsequently, Down syndrome risk was estimated with the three resulting adjusted fß-hCG values. RESULTS: After adjustment, the median ß-hCG MoM decreased from 2.15 MoM to 1.00 MoM (median method), 1.61 MoM (proportionality method) or 1.16 MoM (regression method). The non-adjusted 27% false-positive rate dropped to 18% (median method) and 10% (proportionality or regression methods) after re-estimation of the Down syndrome risk. In controls, the observed median for ß-hCG MoM was 1.12, and the false-positive rate was 5.7%. CONCLUSIONS: In first-trimester Down syndrome screening, fß-hCG adjustment by the regression method appears to be the best to match with controls.

Plasma exogenous creatinine excretion for the assessment of renal function in avian medicine--pharmacokinetic modeling in racing pigeons (Columba livia).

The diagnostic evaluation of the glomerular filtration rate by urinary clearance has significant practical limitations in birds because urine is excreted together with feces. Thus, pharmacokinetic modeling of an exogenous plasma creatinine clearance could be useful for assessing renal creatinine excretion in birds. For this study, creatinine (50 mg/kg) was administered to 2 groups of 15 pigeons (Columba livia) each; in one group by the intravenous (IV) route and in the second by the intramuscular (IM) route. The time series of the plasma creatinine concentrations were analyzed by pharmacokinetic models. Body mass-specific creatinine excretion was determined for IV and IM administration to be between 6.30 and 6.44 mL/min per kg, respectively. Body surface area-specific creatinine clearance, which is related to the metabolic rate, was calculated between 0.506 and 0.523 mL/min per dm2, respectively. The results showed that IV as well as IM administration can be used for assessing renal creatinine excretion in pigeons. For practical reasons, IM administration is recommended, with the use of the Bateman function to calculate creatinine elimination.

Pharmacokinetic study of S-1 in patients in whom inulin clearance was measured.

OBJECTIVE: This pharmacokinetic study of S-1 was conducted in patients in whom glomerular filtration rate (GFR) was directly measured to explore the possibility of adjusting the S-1 dose on the basis of GFR in patients with normal or nearly normal renal function. METHODS: S-1 was given to 12 patients twice daily for 28 consecutive days followed by 14 days of rest, repeated every 6 weeks. GFR was measured on the basis of inulin clearance (CLin) before the first day of treatment. RESULTS: The area under the time-concentration curve (AUC) of 5-fluorouracil (5-FU) correlated with that of 5-chloro-2,4-dihydroxypyridine (CDHP, r = 0.750, p = 0.005). The AUC of CDHP correlated with the measured 24-hour creatinine clearance (CLcr) per subject (r = -0.620, p = 0.032), but not with the CLin (r = -0.356, p = 0.257). The AUC of 5-FU did not correlate with either the 24-hour CLcr per subject (r = -0.401, p = 0.187) or with the CLin (r = -0.300, p = 0.351). CONCLUSION: Dosage adjustment based on the GFR does not reduce individual variations in 5-FU concentrations among patients with normal or nearly normal renal function who receive S-1.

Creatinine clearance is associated with toxicity from molecularly targeted agents in phase I trials.

OBJECTIVES: This study aimed to evaluate any correlations between baseline creatinine clearance and the development of grade 3/4 toxicities during treatment within oncology phase I trials of molecularly targeted agents where entry criteria mandate a serum creatinine of ≤ 1.5 × the upper limit of normal. METHODS: Documented toxicity and creatinine clearance (calculated by the Cockcroft-Gault formula) from all patients treated with molecularly targeted agents in the context of phase I trials within our centre over a 5-year period were analyzed. RESULTS: Data from 722 patients were analyzed; 116 (16%) developed at least one episode of grade 3/4 toxicity. Patients who developed a late-onset (>1 cycle) grade 3/4 toxicity had a lower creatinine clearance than those who did not (82.69 ml/min vs. 98.97 ml/min; p = < 0.001). CONCLUSION: Creatinine clearance (even when within normal limits) should be studied as a potential factor influencing late toxicities in the clinical trials of molecularly targeted anti-cancer drugs.

Low-dose paclitaxel ameliorates fibrosis in the remnant kidney model by down-regulating miR-192.

Transforming growth factor (TGF)-ß has been shown to play a central role in the development of tubulointerstitial fibrosis, which can be corrected via treatment with paclitaxel. The biology of microRNA (miR) can be modulated by paclitaxel. We hypothesized that paclitaxel may attenuate renal fibrosis in a rat model of remnant kidney disease by inhibiting TGF-ß induced-miRs. Rats in groups of 12 were subjected to 5/6 nephrectomy and received low-dose intraperitoneal injection of paclitaxel. Renal functions were assessed at 8 weeks. The TGF-ß signalling cascade and ECM proteins were evaluated by real-time polymerase chain reaction (TRT-PCR) and immunofluorescence microscopy. Animals with remnant kidneys developed hypertension, which was not relieved with paclitaxel treatment. However, paclitaxel treatment resulted in dampening the proteinuric response, reduction in serum BUN, creatinine levels and urine protein : creatinine ratio and normalization of creatinine clearance. These effects were accompanied by the inhibition of Smad2/3 activation, attenuation of renal fibrosis and normalization of integrin-linked kinase (ILK), COL(I)A1, COL(IV)A2 and α-SMA expression. Also, paclitaxel down-regulated the expression of miR-192, miR-217 and miR -377, while miR-15 was up-regulated in the remnant kidney. In vitro, in tubular epithelial cells (NRK-52E), paclitaxel also inhibited TGF-ß1-induced Smad2/3 activation and normalized ILK, COL(I)A1, COL(IV)A2 and α-SMA expression. Furthermore, ChIP analyses indicated that Taxol suppressed Smad3-mediated miR-192 transcriptional activity. Over-expression of miR-192 in NRK-52E mimicked the changes seen in the remnant kidney, while inclusion of miR-192 inhibitor in the culture medium blocked TGF-ß1-induced COL(I)A1 and COL(IV)A2 expression, while ILK and α-SMA were unaffected. These data suggest that low-dose paclitaxel ameliorates renal fibrosis via modulating miR-192 pathobiology and TGF-ß/Smad signalling.

[Evaluation of the renal function in type 2 diabetes: clearance calculation or cystatin C?]. / Évaluation de la fonction rénale chez le diabétique de type 2 : calcul des clairances ou cystatine C ?

Screening for diabetic nephropathy is usually done by albuminuria/24h and the use of creatinine clearance. The objective of this study was to evaluate the renal function in Type 2 diabetes by using different formulas of creatinine clearance and to assess the contribution of cystatin C; 83 adults with type 2 diabetes (23 men and 60 women) and 83 adult controls (40 men and 43 women) were studied. Biochemical parameters were determinated on Coba 6000™ (Roche diagnostics). Diabetics showed a significant increase in blood glucose, cholesterol, triglycerides, LDLc, the ApoB, Lp(a), urea, uric acid, creatinine and cystatin C and lower HDLc. Cystatin was increased in patients with degenerative complications and in hypertensive patients. We found strong correlations of cystatin C with creatinine (r = 0.9454), urea (r = 0.8999) and uric acid (r = 0.8325). We found a significant exponentially increase of creatinine and cystatin C from one stage to another. Cystatin C has a strong association with MDRD (r = 0.8086) and CG (r = 0.7915) and a low one with creatinine clearance (r = 0.1044). In conclusion, the use of cystatin C for screening and early treatment of incipient diabetic nephropathy appears to be adequate. CG and MDRD formulas still hold their place, in regards to the classical determination of creatinine clearance, to monitor patients.

Effect of pre-bypass methylprednisolone on post-operative renal function following correction of atrial septal defect under cardiopulmonary bypass.

Conventional open heart surgery with cardiopulmonary bypass (CPB) are associated with transient post-operative renal dysfunction which is caused by systemic inflammatory response induced by CPB. Corticosteroids are administered to attenuate the systemic inflammatory response. The purpose of this study was to compare the effects of pre-bypass and post-bypass methylprednisolone on postoperative renal function after correction of ASD under CPB. Forty (40) patients were selected in the University cardiac centre of BSMMU undergoing ASD correction under CPB. Patients were randomized into two group to receive pre-bypass (Group A) or post-bypass (Group B) methylprednisolone 30mg/kg. Markers of glomerular function (BUN, serum creatinine, creatinine clearance) and damage (micro-albuminuria) and tubular function (glucosuria) were evaluated 24 hours after operation. Transient impairment of glomerular and tubular function of kidney was observed in patients those received post-bypass metylprednisolone (Group B) while Group A patients shown no significant difference between baseline and post-operative renal function. Use of pre-bypass methylprednisolone has a protective effect on post-operative renal function after correction of ASD under CPB.

Impact of different renal function equations on direct oral anticoagulant concentrations.

The purpose of this study is to investigate the correlation between glomerular filtration rate (GFR) estimated by different renal function equations and non-vitamin K antagonist oral anticoagulant concentration. Atrial fibrillation patients who aged ≥ 20 years and used dabigatran, rivaroxaban, or apixaban for thromboembolism prevention were enrolled to collect blood samples and measure drug concentrations using ultra-high-performance liquid chromatography with tandem mass spectrometry. The GFR was estimated using the Cockroft-Gault formula (abbreviated as creatinine clearance, CrCL), Chronic Kidney Disease Epidemiology Collaboration formula (CKD-EPI) featuring both creatinine and cystatin C, and the Modification of Diet in Renal Disease Study equation (MDRD). Multivariate regression was used to investigate the associations of different renal function estimates with drug concentrations. A total of 511 participants were enrolled, including 146 dabigatran users, 164 rivaroxaban users and 201 apixaban users. Compared to clinical trials, 35.4% of dabigatran, 4.9% of rivaroxaban, and 5.5% of apixaban concentrations were higher than the expected range (p < 0.001). CKD-EPI and MDRD estimates classified fewer patients as having GFR < 50 mL/min than CrCL in all 3 groups. Both CrCL and CKD-EPI were associated with higher-than-expected ranges of dabigatran or rivaroxaban concentrations. Nevertheless, none of the renal function equations was associated with higher-than-expected apixaban concentrations. For participants aged ≥ 75 years, CKD-EPI may be associated with higher-than-expected trough concentration of dabigatran. In conclusion, CrCL and CKD-EPI both can be used to identify patients with high trough concentrations of dabigatran or rivaroxaban. Among elderly patients who used dabigatran, CKD-EPI may be associated with increased drug concentration.

The new high-sensitivity cardiac troponin T assay improves risk assessment in acute coronary syndromes.

BACKGROUND: Cardiac troponins are currently the markers of choice for diagnosis of acute myocardial infarction and risk assessment in acute coronary syndrome (ACS). With the introduction of the new high-sensitivity cardiac troponin T (hs-cTnT) assay, it has become possible to measure cTnT even in healthy subjects. However, how the hs-cTnT assay compares with the old cTnT assay for risk assessment in ACS is still unknown. METHODS: Cardiac troponin T levels were measured with the new hs-cTnT assay and the old third-generation cTnT assay in serum samples collected 48 hours after randomization in 1,452 randomly selected ACS patients enrolled in the GUSTO-IV trial. During 30 days of follow-up, deaths and myocardial infarctions were recorded. At 12 months, only all-cause mortality was collected. RESULTS: The 16% of the patients that had levels higher than the 99th percentile cutoff for hs-cTnT but less than for cTnT had a similar 1-year mortality as the 60% that were positive for both assays (9.2% vs 10.7%, P = .52) and a higher 1-year mortality compared with the 24% that were negative for both assays (9.2% vs 2.6%, P = .001). For death or acute myocardial infarction at 30 days, the group that was positive only for hs-cTnT had an intermediate risk compared with the groups negative or positive for both assays (2.4%, 5.2%, and 8.7%; P < .001). CONCLUSION: The new hs-cTnT assay, compared with the old cTnT assay, identified more patients with myocardial damage and who were at an increased risk for new cardiac events.

Dose Adjustment of Oxaliplatin Based on Renal Function in Patients With Metastatic Colorectal Cancer.

BACKGROUND/AIM: The effect of renal dysfunction on the toxicity and efficacy of oxaliplatin remains unclear. We investigated the association between creatinine clearance (Ccr), a marker of renal function, and the toxicity and efficacy of oxaliplatin in patients with metastatic colorectal cancer (mCRC). PATIENTS AND METHODS: Patients with mCRC who received oxaliplatin-based chemotherapy as first-line treatment were included in this study. Primary outcome was peripheral neuropathy (Grade ≥2), while secondary outcomes included neutropenia (Grade ≥3), thrombocytopenia (Grade ≥2) and overall survival (OS). RESULTS: A total of 145 patients with mCRC were eligible. Incidence rates of peripheral neuropathy (Grade ≥2), neutropenia (Grade ≥3) and thrombocytopenia (Grade ≥2) were 30.3%, 37.2% and 16.6%, respectively, and median OS was 29.1 months. Cox proportional hazards analysis indicated that there was no significant relationship between Ccr and any adverse event, or between Ccr and OS. CONCLUSION: Dose reduction of oxaliplatin based on Ccr is not recommended in patients with mCRC.