Lidocaine In Samples Research Articles

High-Throughput Analysis of Lidocaine in Pharmaceutical Formulation by Capillary Zone Electrophoresis Using Multiple Injections in a Single Run.

This paper reports the development of a subminute separation method by capillary zone electrophoresis in an uncoated capillary using multiple injection procedure for the determination of lidocaine in samples of pharmaceutical formulations. The separation was performed in less than a minute leading to doing four injections in a single run. The cathodic electroosmotic flow contributed to reducing the analyses time. The background electrolyte was composed of 20 mmol L−1 2-amino-2-(hydroxymethyl)-1,3-propanediol and 40 mmol L−1 2-(N-morpholino)ethanesulfonic acid at pH 6.1. The internal standard used was benzylamine. Separations were performed in a fused uncoated silica capillary (32 cm total length, 23.5 cm effective length, and 50 μm internal diameter) with direct UV detection at 200 nm. Samples and standards were injected hydrodynamically using 40 mbar/3 s interspersed with spacer electrolyte using 40 mbar/7 s. The electrophoretic system was operated under constant voltage of 30 kV with positive polarity on the injection side. The evaluation of some analytical parameters of the method showed good linearity (r 2 > 0.999), a limit of detection 0.92 mg L−1, intermediate precision better than 3.2% (peak area), and recovery in the range of 92–102%.

Development of an on-column enrichment technique based on C 18-functionalized magnetic silica nanoparticles for the determination of lidocaine in rat plasma by high performance liquid chromatography

In this study, a novel on-column enrichment technique filled with C 18-functionalized magnetic silica nanoparticles was successfully developed for the determination of lidocaine in rat plasma by high performance liquid chromatography (HPLC). The synthesized Fe 3O 4@SiO 2-C 18 nanoparticles were locally packed into the capillary by the application of magnets. Lidocaine in the sample solutions pumped into the capillary tube could be easily adsorbed by Fe 3O 4@SiO 2-C 18 through hydrophobic interaction by the interior C 18 groups, and eluted by acetonitrile solution. Different extraction conditions were investigated. Method validations including linear range, quantification limit, detection limit, precision, accuracy and recovery were also studied. The results showed that the proposed method based on on-column enrichment by Fe 3O 4@SiO 2-C 18 was a novel, little solvent and efficient approach for the determination of lidocaine in the complex plasma samples.

Spatial distribution of [ 14C]-lidocaine and blood flow in transmural and lateral border zones of ischemic canine myocardium

The purpose of this study was to determine the spatial distribution of lidocaine relative to blood flow in ischemic, normal and border zone canine myocardium. Ischemic zone tissue was distinguished from normal zone tissue by a special microsphere technique in adjacent sections 4 to 5 mm wide from the center to the lateral border of the ischemic region in 14 open chest dogs. Gamma-labeled microspheres were separated by a special technique from carbon-14 ([ 14C])-lidocaine in the same tissue sample. Blood flow (mean value ± 1 standard deviation) was reduced to 46 ± 25 percent of normal in the ischemic subepicardium and 17 ± 18 percent of normal in the subendocardium. [ 14C]-lidocaine was 0.56 ± 0.12 μg/g in normal myocardium 10 minutes after bolus injection of [ 14C]-lidocaine; it was reduced to 91 ± 15 percent of normal in ischemic subepicardium and 58 ± 12 percent of normal in the subendocardium. Blood flow and lidocaine concentration were uniformly lowest in gross samples from the central and intermediate ischemic zones, and highest in the gross samples from the border normal zone (p < 0.05). The values for flow and lidocaine in samples from the border ischemic zone were intermediate, that is, higher than values from central ischemic (p < 0.05) and lower than values from border normal zone samples (p < 0.05). However, the labeling technique for normal zone tissue revealed that the values of blood flow and lidocaine in the gross samples from the lateral border of the ischemic zone were intermediate between those of adjacent ischemic and normal samples because of the mixture of overlapping normal and ischemic tissues components—not because of a unique mildly ischemic region. Both blood flow and lidocaine concentration were lower in the subendocardial third than in the subepicardial third of the ischemic zone (p < 0.05) even after the contribution of normal zone tissue was subtracted, suggesting a gradient of ischemia across the transmural border zone. In conclusion, lidocaine is distributed uniformly in ischemic components from the center to the lateral border of the ischemic zone, but there is an endocardial to epicardial gradient. Both lateral and transmural border zone distributions must be considered to understand the mechanisms of drug effects in myocardial ischemia.