Liquid chromatographic method for the determination of lidocaine and monoethylglycine xylidide in human serum containing various concentrations of bilirubin for the assessment of liver function

A High-Performance Liquid Chromatography Assay Method for the Determination of Lidocaine in Human Serum

Here we report on the development of a selective and sensitive high-performance liquid chromatographic method for the determination of lidocaine in human serum. The extraction of lidocaine and procainamide (internal standard) from serum (0.25 mL) was achieved using diethyl ether under alkaline conditions. After liquid–liquid extraction, the separation of analytes was accomplished using reverse phase extraction. The mobile phase, a combination of acetonitrile and monobasic potassium phosphate, was pumped isocratically through a C18 analytical column. The ultraviolet (UV) wavelength was at 277 nm for the internal standard, and subsequently changed to 210 for lidocaine. The assay exhibited excellent linearity (r² > 0.999) in peak response over the concentration ranges of 50–5000 ng/mL lidocaine HCl in human serum. The mean absolute recoveries for 50 and 1000 ng/mL lidocaine HCl in serum using the present extraction procedure were 93.9 and 80.42%, respectively. The intra- and inter-day coefficients of variation in the serum were <15% at the lowest, and <12% at other concentrations, and the percent error values were less than 9%. The method displayed a high caliber of sensitivity and selectivity for monitoring therapeutic concentrations of lidocaine in human serum.

Effect of Injection Pressure of Infiltration Anesthesia to the Jawbone

To obtain effective infiltration anesthesia in the jawbone, high concentrations of local anesthetic are needed. However, to reduce pain experienced by patients during local anesthetic administration, low-pressure injection is recommended for subperiosteal infiltration anesthesia. Currently, there are no studies regarding the effect of injection pressure on infiltration anesthesia, and a standard injection pressure has not been clearly determined. Hence, the effect of injection pressure of subperiosteal infiltration anesthesia on local anesthetic infiltration to the jawbone was considered by directly measuring lidocaine concentration in the jawbone. Japanese white male rabbits were used as test animals. After inducing general anesthesia with oxygen and sevoflurane, cannulation to the femoral artery was performed and arterial pressure was continuously recorded. Subperiosteal infiltration anesthesia was performed by injecting 0.5 mL of 2% lidocaine containing 1/80,000 adrenaline, and injection pressure was monitored by a pressure transducer for 40 seconds. After specified time intervals (10, 20, 30, 40, 50, and 60 minutes), jawbone and blood samples were collected, and the concentration of lidocaine at each time interval was measured. The mean injection pressure was divided into 4 groups (100 ± 50 mm Hg, 200 ± 50 mm Hg, 300 ± 50 mm Hg, and 400 ± 50 mm Hg), and comparison statistical analysis between these 4 groups was performed. No significant change in blood pressure during infiltration anesthesia was observed in any of the 4 groups. Lidocaine concentration in the blood and jawbone were highest 10 minutes after the infiltration anesthesia in all 4 groups and decreased thereafter. Lidocaine concentration in the jawbone increased as injection pressure increased, while serum lidocaine concentration was significantly lower. This suggests that when injection pressure of subperiosteal infiltration anesthesia is low, infiltration of local anesthetic to the jawbone may be reduced, while transfer to oral mucosa and blood may be increased.

Lidocaine Concentration in Oral Tissue by the Addition of Epinephrine

The vasoconstrictive effect due to the addition of epinephrine to local anesthetic has been clearly shown by measuring blood-flow volume or blood anesthetic concentration in oral mucosal tissue. However, there are no reports on the measurement of anesthetic concentration using samples directly taken from the jawbone and oral mucosal tissue. Consequently, in this study, the effect of lidocaine concentration in the jawbone and oral mucosal tissue by the addition of epinephrine to the local anesthetic lidocaine was considered by quantitatively measuring lidocaine concentration within the tissue. Japanese white male rabbits (n = 96) were used as test animals. General anesthesia was induced by sevoflurane and oxygen, and then cannulation to the femoral artery was performed while arterial pressure was constantly recorded. Infiltration anesthesia was achieved by 0.5 mL of 2% lidocaine containing 1 : 80,000 epinephrine in the upper jawbone (E(+)) and 0.5 mL of 2% of epinephrine additive-free lidocaine (E(0)) under the periosteum. At specified time increments (10, 20, 30, 40, 50, and 60 minutes), samples from the jawbone, oral mucosa, and blood were collected, and lidocaine concentration was directly measured by high-performance liquid chromatography. No significant differences in the change in blood pressure were observed either in E(+) or E(0). In both E(+) and E(0) groups, the serum lidocaine concentration peaked 10 minutes after local anesthesia and decreased thereafter. At all time increments, serum lidocaine concentration in E(+) was significantly lower than that in E(0). There were no significant differences in measured lidocaine concentration between jawbone and mucosa within either the E(+) or the E(0) groups at all time points, although the E(0) group had significantly lower jawbone and mucosa concentrations than the E(+) group at all time points when comparing the 2 groups to each other. Addition of epinephrine to the local anesthetic inhibited systemic absorption of local anesthetic into the blood such that a high concentration could be maintained in the tissue. Epinephrine-induced vasoconstrictive effect was observed not only in the oral mucosa but also in the jawbone.

QM study of complexation between natural bilirubin and poly-terthiophene carboxylic acid–Mn(II) as a biosensor: Temperature and interferences effect

Bilirubin is an insoluble yellow pigment produced from heme catabolism and serves as a diagnostic marker of liver and blood disorders. Here, a systematic study of several interactions and arrangements between different forms of natural bilirubin and poly-5, 2[Formula: see text]-5[Formula: see text], 2[Formula: see text]-terthiophene-3-carboxylic acid/Mn(II)2complex, PTTCA–Mn(II)2, as a biosensor of bilirubin has been investigated extensively. The PTTCA–Mn(II)2biosensor detects natural bilirubin through the mediated electron transfer by the Mn[Formula: see text]. Initially, density functional theory (DFT) using B3LYP and different basis sets including 6-31G* and 6-311G** has been employed to calculate the details of electronic structure and electronic energies of natural biliverdin and [Formula: see text]-, [Formula: see text]- and [Formula: see text]-bilirubin. Next, the interaction of the PTTCA–Mn(II)2biosensor, being in three possible spin states, with [Formula: see text]-, [Formula: see text]- and [Formula: see text]-natural bilirubin with 1:1 and 1:2 stoichiometry using UB3LYP/6-31G* method has been investigated. Natural population analysis (NPA) calculations have been used to derive more suitable interaction sites of bilirubin with Mn[Formula: see text] ions in PTTCA–Mn(II)2biosensor. Investigation of different manganese complexes with bilirubin shows that the most stable complex is high spin state (total electron spin [Formula: see text]) rather than intermediate and low spin states with 1:2 stoichiometry. Also, the temperature effect and interferences from other biological compounds such as ascorbic acid, L-glutamic acid, uric acid, creatine, glucose and dopamine have been investigated. The nature of the interaction between manganese metal cations and natural bilirubin is also discussed employing NPA, molecular orbital (MO) analysis and Bader’s Atoms in Molecule (AIM) theory.

Lidocaine concentration in mandibular bone after subperiosteal infiltration anesthesia decreases with elevation of periosteal flap and irrigation with saline

It has been reported that the action of infiltration anesthesia on the jawbone is attenuated significantly by elevation of the periosteal flap with saline irrigation in clinical studies; however, the reason is unclear. Therefore, the lidocaine concentration in mandibular bone after subperiosteal infiltration anesthesia was measured under several surgical conditions. The subjects were 48 rabbits. Infiltration anesthesia by 0.5 mL of 2% lidocaine with 1 : 80,000 epinephrine (adrenaline) was injected into the right mandibular angle and left mandibular body, respectively. Under several surgical conditions (presence or absence of periosteal flap, and presence or absence of saline irrigation), both mandibular bone samples were removed at a fixed time after subperiosteal infiltration anesthesia. The lidocaine concentration in each mandibular bone sample was measured by high-performance liquid chromatography. As a result, elevation of the periosteal flap with saline irrigation significantly decreased the lidocaine concentration in the mandibular bone. It is suggested that the anesthetic in the bone was washed out by saline irrigation. Therefore, supplemental conduction and/or general anesthesia should be utilized for long operations that include elevation of the periosteal flap with saline irrigation.

Effect of mild and moderate liver disease on the pharmacokinetics of isavuconazole after intravenous and oral administration of a single dose of the prodrug BAL8557

Isavuconazole is a promising new antifungal drug with favorable pharmacokinetic properties and excellent activity against a number of fungi. It is administered as a water-soluble prodrug (BAL8557) that is cleaved by plasma esterases to isavuconazole, which is eliminated primarily by hepatic metabolism. The objective of this investigation was to assess the effect of alcohol-related liver disease on the pharmacokinetics of isavuconazole. Subjects were 16 healthy individuals, 16 with mild liver impairment, and 16 with moderate liver impairment who were randomized to receive a single oral or intravenous dose of BAL8557 equivalent to 100 mg isavuconazole. Blood samples were collected for 21 days following drug administration, and plasma concentrations of isavuconazole, BAL8557, and the cleavage product BAL8728 were measured using high-pressure liquid chromatography coupled with tandem mass spectrometry. Following intravenous administration, the half-life of isavuconazole increased from 123 h for healthy volunteers to 224 h and 302 h for subjects with mild and moderate liver impairment, respectively. The systemic clearance of isavuconazole following intravenous administration decreased from 2.73 liters/h for healthy subjects to 1.43 liters/h for subjects with moderate liver impairment (47.6% decrease [P < 0.05]). A similar decrease (23.5%) was observed after oral administration. These results suggest that a dose adjustment may be needed when isavuconazole is used to treat fungal infections in patients with liver disease.

Study on the pharmacokinetics drug-drug interaction potential of Glycyrrhiza uralensis, a traditional Chinese medicine, with lidocaine in rats

Drug-drug interaction potentials of an herbal medicine named Glycyrrhiza uralensis was investigated in rats via in vitro and in vivo pharmacokinetic studies. P(450) levels and the metabolic rate of lidocaine in the liver microsomes prepared from different treatment groups were measured. In a separate in vivo pharmacokinetic study, the pharmacokinetic parameters of lidocaine in plasma and urine were estimated. P(450) levels in the rats pretreated by Glycyrrhiza uralensis were significant higher than that in the non-treatment control. The increase in P(450) levels was dose-dependent. Glycyrrhiza uralensis (1 and 3 g/kg) increased P(450) levels by 62% and 91%, respectively, compared with the non-treatment control (0.695 nmol/mg protein). The metabolic rate of lidocaine in the liver microsomes was significantly higher in the herb pretreated rats. The pharmacokinetic profile of lidocaine was significantly modified in the rats with the herbal pretreatment. Elimination half-lives were shortened by 39%, and total clearances were increased by 59% with the pretreatment of Glycyrrhiza uralensis. In conclusion, Glycyrrhiza uralensis showed induction effect on P(450) isozymes. Efficacy and safety profiles of a drug may be affected when the herbal products or herbal prescriptions containing the plant medicine were concomitantly used.

Simultaneous determination of ethamsylate, tramadol and lidocaine in human urine by capillary electrophoresis with electrochemiluminescence detection

Ethamsylate, tramadol and lidocaine, partly excreted by the kidney, are generally used as hemostatic, analgesic and local anesthetic in surgery. We developed a simple and sensitive method for their simultaneous monitoring in human urine based on CE coupled with electrochemiluminescence detection by end-column mode. Under optimized conditions the proposed method yielded linear ranges from 5.0 x 10(-8) to 5.0 x 10(-5), 1.0 x 10(-7) to 1.0 x 10(-4) and 1.0 x 10(-7) to 1.0 x 10(-4) M with LODs of 8.0 x 10(-9) M (36 amol), 1.6 x 10(-8) M (72 amol) and 1.0 x 10(-8) M (45 amol) (S/N = 3) for ethamsylate, tramadol and lidocaine, respectively. The RSD for their simultaneous detection at 1.0 x 10(-6) M was 2.1, 2.8 and 3.2% (n = 7), respectively. For practical application an extraction step with ethyl acetate at pH 11 was performed to eliminate the influence of the sample ionic strength. The recoveries of ethamsylate, tramadol and lidocaine at different levels in human urine were between 87 and 95%. This method was used for simultaneous detection of ethamsylate, tramadol and lidocaine in clinic urine samples from two medicated patients. It was valuable in clinical and biochemical laboratories for monitoring these drugs for various purposes.

Utility of nonaqueous capillary electrophoresis for the determination of lidocaine and its metabolites in human plasma: a comparison of ultraviolet and mass spectrometric detection

A nonaqueous capillary electrophoresis/electrospray mass spectrometry method for the separation of lidocaine (LID) and two of its metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX), has been developed. The separation medium was: 70 mM ammonium formate and 2.0 M formic acid in acetonitrile/methanol (60:40 v/v). With a sheath liquid of methanol/water (80:20 v/v) containing 2% formic acid and positive ion detection, reproducible determinations (8-11% relative standard deviation (RSD)) of lidocaine and its metabolites were performed in spiked human plasma. The limits of detection (LODs) were between 69.1 and 337 nM. The influences of sheath liquid composition, nebulizing gas pressure and drying gas temperature on the separation were examined.