Argatroban versus heparin in patients without heparin-induced thrombocytopenia during venovenous extracorporeal membrane oxygenation: a propensity-score matched study.

BACKGROUND: During venovenous extracorporeal membrane oxygenation (vvECMO), direct thrombin inhibitors are considered by some potentially advantageous over unfractionated heparin (UFH). We tested the hypothesis that Argatroban is non-inferior to UFH regarding thrombosis and bleeding during vvECMO. METHODS: We conducted a propensity-score matched observational non-inferiority study of consecutive patients without heparin-induced-thrombocytopenia (HIT) on vvECMO, treated between January 2006 and March 2019 in the medical intensive care unit at the University Hospital Regensburg. Anticoagulation was realized with UFH until August 2017 and with Argatroban from September 2017 onwards. Target activated partial thromboplastin time was 50 ± 5seconds in both groups. Primary composite endpoint was major thrombosis and/or major bleeding. Major bleeding was defined as a drop in hemoglobin of ≥ 2 g/dl/day or in transfusion of ≥ 2 packed red cells/24 h, or retroperitoneal, cerebral, or pulmonary bleeding. Major thrombosis was defined as obstruction of > 50% of the vessel lumen diameter by means of duplex sonography. We also assessed technical complications such as oxygenator defects or pump head thrombosis, the time-course of platelets, and the cost of anticoagulation (including HIT-testing). RESULTS: Out of 465 patients receiving UFH, 78 were matched to 39 patients receiving Argatroban. The primary endpoint occurred in 79% of patients in the Argatroban group and in 83% in the UFH group (non-inferiority for Argatroban, p = 0.026). The occurrence of technical complications was equally distributed (Argatroban 49% vs. UFH 42%, p = 0.511). The number of platelets was similar in both groups before ECMO therapy but lower in the UFH group after end of ECMO support (median [IQR]: 141 [104;198]/nl vs. 107 [54;171]/nl, p = 0.010). Anticoagulation costs per day of ECMO were higher in the Argatroban group (€26 [13.8;53.0] vs. €0.9 [0.5;1.5], p < 0.001) but not after accounting for blood products and HIT-testing (€63 [42;171) vs. €40 [17;158], p = 0.074). CONCLUSION: In patients without HIT on vvECMO, Argatroban was non-inferior to UFH regarding bleeding and thrombosis. The occurrence of technical complications was similarly distributed. Argatroban may have less impact on platelet decrease during ECMO, but this finding needs further evaluation. Direct drug costs were higher for Argatroban but comparable to UFH after accounting for HIT-testing and transfusions.

Serum reference intervals of homoarginine, ADMA, and SDMA in the study of health in Pomerania.

BACKGROUND: Low circulating homoarginine as well as high levels of asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) have been associated with impaired cardiovascular (CV) outcome and mortality in patients at risk and in the general population. The present study aimed to formulate reference intervals for serum homoarginine, ADMA, and SDMA to improve risk stratification between healthy individuals and individuals at risk. METHODS: We determined age- and sex-specific reference intervals for homoarginine, ADMA, and SDMA in a subgroup of 1359 healthy participants (no diabetes mellitus, CV disease, increased blood pressure, elevated blood lipids, chronic kidney disease stadium III or IV, or a body mass index >30) of the Study of Health in Pomerania (SHIP) using quantile regression analyses. Homoarginine, ADMA, and SDMA serum concentrations were measured using liquid chromatography-tandem mass spectrometry. RESULTS: Median age of the investigated cohort was 36 (25th; 75th percentile 28; 47) years, with 62% women. Median serum concentrations of homoarginine, ADMA, and SDMA were 2.63 (2.08; 3.32) µmol/L, 0.64 (0.57; 0.73) µmol/L, and 0.43 (0.37; 0.49) µmol/L, respectively. Serum levels of homoarginine, ADMA, and SDMA showed material age- and sex-related differences (p<0.05 for all). Overall reference ranges were 1.41-5.00 and 1.20-5.53 µmol/L (2.5th; 97.5th percentile; for men and women, respectively) for homoarginine, 0.41-0.95 and 0.43-0.96 µmol/L for ADMA, and 0.30-0.67 and 0.27-0.63 µmol/L for SDMA. CONCLUSIONS: We formulated for the first time homoarginine, ADMA, and SDMA reference intervals in serum. These reference intervals might be useful for individual CV risk stratification.

Fourier transform near-infrared spectroscopy used for purity determination of rhein-L-arginine cocrystal (argirein).

A method is described using rapid and sensitive Fourier transform near-infrared spectroscopy (FT-NIRS) for the determination of rhein-L-arginine cocrystal (argirein). By mixing different values of argirein into different proportions with rhein and arginine, we obtained 41 batches of samples to deatermine. Partial least squares (PLS) regression was selected as the analysis type and standard normal variate (SNV) and original spectra were adopted for the spectral pretreatment. The correlation coefficient (R) of the calibration model was above 0.99 and the root mean square error of predictions (RMSEP) was under 0.012. The developed model was applied to 10 batches of known samples with satisfactory results. The established method is validated and can be applied to the intrinsic quality control of synthetic products and other cocrystals.

HPLC analysis of asymmetric dimethylarginine (ADMA) and related arginine metabolites in human plasma using a novel non-endogenous internal standard.

BACKGROUND: Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthesis which has been implicated in the endothelial dysfunction. Methods for ADMA measurement often yield widely differing results, and few methods simultaneously offer satisfactory accuracy and precision. We describe a fully validated HPLC method for analysis of arginine and its methylated derivatives in human plasma using a novel internal standard. METHODS: Arginine and related metabolites are extracted from plasma by solid phase extraction (SPE), derivatised with ortho-phthaldialdehyde and separated by isocratic reverse phase chromatography. Monoethylarginine (MEA), which is not endogenously present in human plasma was used as internal standard. SPE and chromatographic procedures are optimised and recovery, precision, linearity and sensitivity of the assay established. The suitability and performance of MEA is compared with that of monomethylarginine (MMA), the internal standard most commonly used in HPLC methods. RESULTS: SPE yields high and reproducible recoveries (>90%). The analytes of interest are chromatographically well resolved. The method has high sensitivity (LOD, 0.01 micromol/L for arginine and 0.001 micromol/L for ADMA, SDMA and homoarginine) and good precision (CV, 2.5% for ADMA). The data obtained with the internal standards MEA and MMA is comparable in terms of assay precision and population reference intervals. CONCLUSIONS: We describe an optimised isocratic HPLC method for the simultaneous measurement of arginine and related metabolites in plasma which exhibits satisfactory precision and is suitable for routine use. Its main advantage over other published HPLC methods is the use of the novel internal standard, MEA, which unlike other commonly used internal standards is not inherent in human plasma.

Determination of dimethylarginine levels in rats using HILIC-MS/MS: an in vivo microdialysis study.

Nitric oxide (NO) is one of the most important mediators and neurotransmitters and its levels change under pathological conditions. NO production may be regulated by endogenous nitric oxide synthase (NOS) inhibitors, in particular asymmetric dimethylarginine (ADMA). Most of the interest is focused on ADMA, since this compound is present in plasma and urine and accumulation of ADMA has been described in many disease states but little is known about cerebrospinal fluid (CSF) concentrations of this compound and of its structural isomer symmetric dimethylarginine (SDMA). To determine the levels of methylarginines, we here present a new hydrophilic interaction chromatography (HILIC)-MS/MS method for the precise determination of these substances in CSF from microdialysis samples of rat prefrontal cortex (PFC). The method requires only minimal sample preparation and features isotope-labelled internal standards.

Evaluation of mobile phase, ion pairing, and temperature influence on an HILIC-MS/MS method for L-arginine and its dimethylated derivatives detection.

Asymmetric N(G),-N(G)-dimethylarginine (ADMA) increases in diseases such as renal failure, diabetes mellitus, and hypercholesterolemia. The feasibility and utility of a hydrophilic interaction chromatography (HILIC) method for the separation of free L-arginine (Arg), ADMA, and symmetric N(G),-N(G')-dimethylarginine (SDMA) on a typical silica column were explored and the impact of some experimental parameters on the chromatographic behavior of these analytes was investigated. The effect of water and TFA content in mobile phase and of column temperature was investigated during the development of a fast and simple HILIC-MS/MS method that might be suitable for the quantification of free Arg, ADMA, and SDMA in plasma for routine analysis. Our results show that a good compromise between efficiency and peak shape with acceptable retention and total chromatographic run time is achieved using an ACN/water (90:10) mobile phase with TFA% as additive ranging from 0.015 to 0.025% and column temperature ranging from 25 to 30 degrees C.