High-pressure liquid chromatographic determination of plasma dobutamine concentrations

Electrochemical sensing of dobutamine, paracetamol, amlodipine, and daclatasvir in serum based on thiourea SAMs over nano-gold particles-CNTs composite

We report in this work a one-step approach for the formation of self-assembled monolayers (SAMs) from thiourea (TU) over gold nanoparticles dispersed in carbon nanotubes (CNTs-Aunano). The fabrication of the...

A sensitive method for the simultaneous UHPLC-MS/MS analysis of milrinone and dobutamine in blood plasma using NH4F as the eluent additive and ascorbic acid as a stabilizer

The purpose of this work was to develop and validate an HPLC-MS/MS method suitable for quantifying two important cardiovascular drugs, milrinone and dobutamine, in neonatal and paediatric patients' blood plasma samples. Sufficiently low LLOQ levels were required to obtain adequate pharmacokinetic data for the evaluation of optimal dosing. Since the specifics of the patient group set some restrictions on the available sample volume, the method was designed to use only 20 µL of plasma for the analysis. Analytes were separated chromatographically in a biphenyl column using a conventional water-methanol-formic acid eluent with the addition of ammonium fluoride. The latter provided a significant signal enhancement in positive ion mode detection for both analytes allowing the LLOQ to reach below 1 ng/mL. Matrix matched calibration was linear in the range of 1-300 ng/mL, between-run accuracy remained within 107-115%, and precision within 4.8-7.4% for both analytes over the calibration range (including LLOQ level). Dobutamine degradation in plasma samples was prevented by the usage of ascorbic acid. The method was applied to plasma samples of neonates from two pharmacokinetic/pharmacodynamics studies (n = 38).

Spectrophotometric determination of some catecholamine drugs using sodium bismuthate

A novel spectrophotometric method is described for the determination of epinephrine (EP) and norepinephrine (NE). The method is based on the development of a red colour with sodium bismuthate, as a sensitive chromogenic reagent, in aqueous medium at pH 3. Oxidation of these catecholamines produces aminochrome derivatives which can be measured spectrophotometrically at 486.0 nm. Calibration graphs are linear in the range 4.8-800 (micromol l(-1)) for epinephrine bitartarate and 4.8-600 (micromol l(-1)) for norepinephrine bitartarate with detection limits of 0.26 (micromol l(-1)) and 2.46 (micromol l(-1)) for epinephrine and norepinephrine bitartarate salts, respectively. The method has successfully been applied to determination of these catecholamines in pharmaceutical preparations.

Pulmonary extraction of dobutamine in critically ill surgical patients

This study was conducted to assess the pulmonary extraction of dobutamine. Eleven patients admitted to the general surgical intensive care unit, with varying diagnoses requiring dobutamine as part of their therapeutic intervention, were included. A single simultaneous sample was drawn, at the clinically required rate of infusion, from the radial and pulmonary artery catheter sites. Total dobutamine clearance was determined using the pulmonary artery (pre-lung) sample. The mean +/- SD total dobutamine clearance was 82 +/- 67 mL.kg-1.min-1 a value which is larger than the average cardiac output of plasma of 56 +/- 20 mL.kg-1.min-1. The mean percent pulmonary extraction fraction of dobutamine was 3.6% +/- 22.5% (range -34-52), a value within the 9% coefficient of variability (CV) of the assay. However, five patients had pulmonary extraction greater than the CV of the assay. Of these five patients, three had "negative" extraction values, and two had "positive" extraction values. There was no relationship between the percent pulmonary extraction of dobutamine and the rate or duration of dobutamine infusion before sampling. The results show that the extraction of dobutamine by the lungs is minimal.

Determination of dopexamine hydrochloride in human blood by high-performance liquid chromatography with electrochemical detection

A method is described for the determination of dopexamine hydrochloride at concentrations of 5 to 100 ng/ml in human blood using electrochemical detection. The method uses a Hypersil ODS column and a mobile phase containing heptane sulphonate, orthophosphoric acid, diisopropylamine and disodium EDTA. Blood samples are stabilised immediately after collection by the use of dipotassium EDTA and a high concentration of sodium metabisulphite. The sample preparation procedure consists of a simple de-proteinisation with perchloric acid. The method is accurate, with inter-assay accuracies ranging from 100 to 104%, and is free of interference by blood from different individuals. Known and potential metabolites of dopexamine hydrochloride and a wide range of drugs do not interfere with the method. The method is precise with inter-assay coefficients of variation of 10.6% at 5 ng/ml and of less than 4.2% at higher concentrations. Stabilised blood samples may be stored for over six months at -25 degrees C prior to analysis.

Solid phase extraction and high performance liquid chromatographic determination of dobutamine in plasma of dialysed patients

An isocratic reversed-phase high performance liquid chromatographic method has been developed for th e determination of dobutamine in the plasma of dialysed patients. A solid phase extraction method with a Sep-Pak C18 cartridge was used to isolate the drug and isoxsuprine (internal standard) from plasma. The separation was carried out on an ODS-Hypersil column with 0.1 M phosphate buffer:acetonitrile:methanol (72:20:8 v/v/v) as the mobile phase. The recovery of dobutamine added to plasma by the extraction procedure was 87 +/- 2.3% (mean +/- SD). The accuracy and reproducibility of the method were within acceptable limits over the concentration range 0-1000 ng/mL. Quantification was by fluorescence detection at 275 nm excitation and 310 nm emission wavelengths with a detection limit of 5 ng/mL for dobutamine. This procedure was applied to ascertain the pharmacokinetics of dobutamine infusion in nine patients with cardiogenic shock and end-stage renal disease undergoing haemodialysis.

Rapid and sensitive assay of dobutamine in plasma by high-performance liquid chromatography and electrochemical detection

A sensitive and specific high-performance liquid chromatographic method with electrochemical detection was developed for measuring dobutamine in human plasma samples. Following an external standard method, 0.1 ml of EDTA-glutathione plasma was diluted on ice with 0.2 ml of a 5% trichloracetic acid solution. The mixture was centrifuged, filtered, and 30 microliters were injected. Assessment was done by electrochemical detection. The assay was linear from 1 to 400 ng/ml plasma. For determination of dobutamine we also used a liquid-liquid extraction method routinely applied for plasma catecholamines. Liquid-liquid extraction requires application of 100-1000 microliters of plasma. The standard curve was linear from 0.1 to 600 ng/ml. Absolute recovery of dobutamine was 90 +/- 3% with the liquid-liquid extraction procedure and 91 +/- 3% with the protein precipitation method. For both methods dobutamine was separated on Nova-Pak C18 columns. The mobile phase used was 0.1 molar phosphate buffer-acetonitrile (80:20, v/v) with 1-octanesulfonic acid and triethylamine as ion-pair reagents. The pH was adjusted to 2.7.

Simultaneous determination of catecholamines and dobutamine in human plasma and urine by high-performance liquid chromatography with fluorimetric detection

We report a reliable fluorimetric assay for the simultaneous determination of norepinephrine, epinephrine, dopamine and dobutamine in human plasma and urine, based on liquid-liquid extraction and derivatization with the fluorogenic agent 1,2-diphenylethylenediamine prior to chromatography. The method is sensitive (detection limit 0.3-0.8 pg injected) and reproducible (coefficients of variation 1-10%), and shows good accuracy (93-98%). The method should also be used when one only wants to measure the concentrations of the natural catecholamines, in order to avoid interference by metabolites of dobutamine and by the late-eluting dobutamine itself.

Drug level monitoring: cardiovascular drugs

Methods for the determination of cardiovascular drugs in blood and plasma are critically reviewed with emphasis on gas and liquid chromatographic techniques. The importance of the various procedures is discussed, in particular sample work-up where the conditions for isolation and derivatization of the compounds are decisive for the accuracy and precision of the methods. Compared with other assay techniques chromatographic methods are generally to be preferred owing to their better selectivity. In the review the following groups are discussed: digitalis glycosides, antiarrhythmic agents, beta-adrenoceptor antagonists, vasodilating agents, antihypertensive compounds, and diuretics.

The relationship between plasma dobutamine concentrations and cardiovascular responses in cardiac failure

Plasma dobutamine concentrations and hemodynamic and noninvasive cardiac measurements were made during dobutamine infusions in eight patients with congestive cardiomyopathy and low output heart failure. Plasma concentrations correlated well with infusion rates (2.5, 5.0, 7.5 and 10 microgram/kg/min). Cardiac output and stroke volume increased linearly, whereas pulmonary capillary wedge pressure, and total pulmonary and systemic resistances decreased linearly with increasing dobutamine concentrations. No constant relationship existed between plasma dobutamine levels and changes in heart rate or mean arterial pressure. The noninvasive left ventricular function data (echocardiographic and systolic time intervals) correlated linearly with plasma concentrations and suggest that these noninvasive technics be employed in guiding the administration of this new inotropic agent.