Tris(2,2'-bipyridyl)ruthenium(II)-zirconia-Nafion composite films applied as solid-state electrochemiluminescence detector for capillary electrophoresis

The major goal of this work was to develop a new solid-state electrochemiluminescence (ECL) detector suitable for capillary electrophoresis (CE). The detector was fabricated by coating a sol-gel derived zirconia (ZrO(2))-Nafion composite film on a graphite electrode, then the zirconia-Nafion modified electrode was immersed in tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)(3) (2+)) solution to immobilize this active chemiluminescence reagent. The voltammetric and ECL behaviors of the detector were investigated and optimized in tripropylamine solution. The ratio of 53% for zirconia in the zirconia-Nafion composite provided the highest luminescence intensity of immobilized Ru(bpy)(3) (2+). The ECL can maintain its stability very well in the phosphate solution in the period of 5-90 h when the solid-state ECL detector was immersed in the solution all the time. The optimum distance of capillary outlet to the solid-state ECL detector has been found to be ca. 50-80 microm for a 75 microm capillary. The effects of ionic strength and pH of ECL solution on peak height were investigated. The CE with solid-state ECL detector system was successfully used to detect tripropylamine, lidocaine, and proline. The detection limits (S/N = 3) were 5 x 10(-9) mol.L(-1) for tripropylamine, 1 x 10(-8) mol.L(-1) for lidocaine and 5 x 10(-6) mol.L(-1) for proline, and the linear ranges were from 1.0 x 10(-8) to 1.0 x 10(-5) mol.L(-1) for tripropylamine, 5.0 x 10(-7) mol.L(-1) to 1.0 x 10(-5) mol.L(-1) for lidocaine and 1.0 x 10(-5) to 1.0 x 10(-3) mol.L(-1) for proline, respectively.

Analysis of lidocaine and its major metabolite, monoethylglycinexylidide, in elk velvet antler by liquid chromatography with UV detection and confirmation by electrospray ionization tandem mass spectrometry

A sensitive liquid chromatographic (LC) method with UV detection was developed for the determination of residues of lidocaine (LID) and its major metabolite, monoethylglycinexylidide (MEGX), in elk velvet antler. The drugs were extracted from alkaline velvet antler homogenates, cleaned up on a C(18) solid-phase extraction cartridge, and separated on an Inertsil ODS-3 (3.0 x 250 mm, 5 microm) column using an isocratic mobile phase made up of 0.05 M phosphate buffer (pH 4.0)/acetonitrile (88:12, v/v) at a flow rate of 1.0 mL/min. The limits of quantification for LID and its major metabolite, MEGX, were 10 and 20 ng/g, respectively. The method was validated and used to measure the concentration of residues of LID and MEGX in elk velvet antlers harvested after either LID anesthesia or application of a drug-free control method (electro-anesthesia, EA). No LID or MEGX residues were detected in any of the antlers harvested after EA application. No MEGX residues were detected in any of the velvet antlers harvested after LID application, but residues of LID ranging in concentration from 68 to 4300 ng/g were detected in the three sections of the velvet antlers harvested after LID administration. LC-tandem mass spectrometry was used to confirm the presence of lidocaine detected in the velvet antlers.

Monoethylglycinexylidide and lidocaine determination in porcine microsomal preparations

A simple, accurate, and sensitive HPLC analysis of monoethylglycinexylidide (MEGX) and lidocaine in porcine microsome samples is described. Lidocaine and MEGX were measured by direct injection after the addition of the internal standard. Chromatography was performed on a muBondapak C(18) column using an isocratic mobile phase of 0.03 M potassium dihydrogen phosphate:acetonitrile (87:13), pH 5.9. UV absorbance was measured at 205 nm. The procedure produced linear curves for the concentration range 50-1000 ng/mL with a limit of detection of 10 ng/mL. Recoveries for both compounds were greater than 90%. This assay produced accurate and repeatable results.

Development and validation of RP–HPLC method for cetrimonium bromide and lidocaine determination

The simple and rapid RP-HPLC method, for the simultaneous determination of lidocaine and cetrimonium bromide in the presence of pellet color corrigent, was developed. Separations were performed on a Beckman Ultrasphere ODS 4.6 mm x 15 cm, 5 microm particle column at 40 degrees C. The mobile phase consisted of water phase and acetonitrile (72:28 V/V), pH value of the mobile phase was adjusted to 2.0 with 85% ortophosphoric acid. Bisacodil was used as an internal standard. The flow rate was 1 ml/min and UV detection was performed at 208 nm. The proposed RP-HPLC method was validated and all the parameters for the validation of the method are given. According to the obtained results, the developed method was found to be suitable and accurate for the determination of these drugs in commercial formulations.

Characterization of cellulosic hot-melt extruded films containing lidocaine

Hot-melt extrusion technology was used to produce thin films containing a model drug, lidocaine, and the cellulosic polymers hydroxypropyl cellulose (HPC) and hydroxypropyl methyl cellulose (HPMC). Two film formulations were extruded and compared, one containing only HPC and the other containing HPC:HPMC (80:20). Thermal analysis of the films using differential scanning calorimetry (DSC) suggested that the drug existed in the amorphous condition, which was confirmed by wide angle X-ray diffractometry. Sustained release of the drug was observed from both of the polymer matrices. Dissolution profiles suggested that HPMC retarded the drug release from HPC:HPMC (80:20) films. However, the mechanism of drug release from both of the films was predominantly diffusion of the drug through the polymer matrices. Incorporation of HPMC also increased both adhesive strength and work of adhesion as compared to the HPC-only films.

About an unusual case: GC-MS detection of lidocaine

A man suspected to be a drug user was found dead; toxicological analysis of his biological samples showed the presence of lidocaine in all samples analysed, while cocaine was found only in the blood, urine and hair samples. We found that the cause of death was determined by ventricular arrhythmia associated to lidocaine/cocaine overdosage.

Short-capillary electrophoresis with electrochemiluminescence detection using porous etched joint for fast analysis of lidocaine and ofloxacin

Fast analysis of ofloxacin and lidocaine, as bactericide and analgesic or anesthetics, is of clinic importance for understanding the patient's medical process. This paper presented a high throughput, simple analysis method of lidocaine and ofloxacin by capillary electrophoresis coupled with electrochemiluminescence (ECL) using porous etched joint. To shorten the analysis time and to improve the analytical performance, a capillary with 10 cm in length was used as the separation channel. The cyclic voltammograms of Ru(bpy)3(2+) with different capillary length at same field strength showed that the porous etched joint eliminated the effect of electrophoretic current on the ECL detection. Following micro total analysis systems (microTAS), some advantages of which this approach has, the fabrication of channel in chip was not needed. Compared with capillary electrophoresis with 40-cm-long capillary, the high sample throughput and low zone broadening may be the main advantage of the present system. Under optimal condition, the detection limits of lidocaine and ofloxacin based on peak height were 3.0 x 10(-8) and 5.0 x 10(-7) molL(-1) and a 60 h(-1) of sampling frequency was obtained. The precision (R.S.D.) of the migration time and the peak height for five replicate injections of a mixture of lidocaine (1.0 x 10(-6) molL(-1)) and ofloxacin (4.0 x 10(-6) molL(-1)) were 3.2-3.9% and 4.7-5.3%, respectively.

A fatal case of poisoning by lidocaine overdosage--analysis of lidocaine in formalin-fixed tissues: a case report

The death of a 76-year-old man with heart disease as a result of the injection of an excessive dose of lidocaine is presented. The patient was given 5 ml of 10% lidocaine hydrochloride (500 mg) intravenously instead of 2.5 ml of 2% lidocaine hydrochloride (50mg) in order to treat repeated paroxysmal ventricular arrhythmia. Immediately following the injection the patient had tonic clonic seizures and complete cardiopulmonary arrest followed. Although resuscitation attempts once successfully restarted his pulse and spontaneous respiration, the patient died on the eighth day after the injection. Toxicological examinations were carried out on the tissues obtained at the time of autopsy and which had been fixed in formalin solution for 40 days, and lidocaine was detected in each tissue examined. The concentrations were (ng/g or ml): parietal lobe, 308.0; occipital lobe, 208.7; temporal lobe, 318.0; frontal lobe, 223.2; cerebellum 200.9; pons 285.7; liver, 109.5; kidney 52.2; skeletal muscle 127.0; and formalin solution 8.4. In an experiment on rats we determined the concentration changes of lidocaine in formalin fixed tissues. The concentrations of lidocaine in these tissues significantly decreased to 1/3-1/4 from the original. This data shows that the cause of death was poisoning by lidocaine overdose.

Use of control sample for estimation of prediction error in multivariate determination of lidocaine solutions with non-column chromatographic diode array UV spectroscopy

The aim of this study was to investigate the ability of a control sample, of known content and identity, to diagnose and correct errors in the predictions when the same multivariate calibration model was used for analysis of new samples over time. A calibration set consisting of 16 samples with a known content of lidocaine was analysed and two external test sets, A and B, were used for the validation. Test set A contained 15 samples with different concentrations of lidocaine and test set B contained three samples with different lidocaine content, which were analysed six times in order to obtain a measure of repeatability. The multivariate calibration was done with PLS regression on UV spectra collected between 245 and 290 nm. A representative UV spectrum was exported from the collected DAD files by two methods, average spectrum over the whole file and average spectrum over the sample plug. Test set A was analysed further on another three occasions together with a control sample. The results showed that the control sample could be used to give a diagnosis and estimate of the prediction error. Moreover, the measured prediction error of the control sample could also be used to correct the predictions, thereby reducing the prediction error. Finally, some practical considerations regarding use of the proposed DAD method with a control sample are presented. The procedure suggested could lead to an efficient analytical approach where the same calibration model could be used over time without recalibration, which may be attractive in industrial quality control or screening analysis in pharmaceutical research.

Validation of capillary electrophoresis--mass spectrometry methods for the analysis of a pharmaceutical formulation

The coupling of capillary electrophoresis (CE) to mass spectrometry (MS) with an electrospray ionization (ESI) technique is generally performed for qualitative applications, and only few quantitative results have been reported. This paper investigates the validation of a CE-ESI-MS method for the analysis of a pharmaceutical formulation containing lidocaine. Some important ESI criteria are discussed including sheath-liquid composition, nebulizing gas pressure and position of the CE capillary outlet. After optimization of these parameters, an intermediate precision of about 5% was achieved. The latter, as well as efficiency and resolution, were compared to those achieved with UV detection. Besides, a multiple injection procedure was developed to reduce analysis time per sample and was successfully applied to both UV and MS detectors. The validation results achieved by multiple injections were identical to those obtained with classical injection, but afforded a gain of time by a factor of 2.5.

Simultaneous micellar LC determination of lidocaine and tolperisone

A micellar liquid chromatography (MLC) procedure was developed for the simultaneous separation and determination of lidocaine hydrochloride (LD HCl) and tolperisone hydrochloride (TP HCl) using a short-column C18 (12.5 mm x 4.6 mm, 5 microm), sodium dodecyl sulfate (SDS) with a small amount of isopropanol, and diode array detector. The optimum conditions for the simultaneous determination of both drugs were 0.075 mol l(-1) SDS-7.5% (v/v) isopropanol with a flow rate of 0.7 ml min(-1) and detection at 210 nm. The LOD (2S/N) of LD HCl was 0.73 ng 20 microl(-1), whereas that of TP HCl was 1.43 ng 20 microl(-1). The calibration curves for LD HCl and TP HCl were linear over the ranges 0.125-500 microg ml(-1) (r(2)=0.9999) and 1.00-500 microg ml(-1) (r(2)=0.9997), respectively. The %recoveries of both drugs were in the range 98-103% and the %RSD values were less than 2. The proposed method has been successfully applied to the simultaneous determination of TP HCl and LD HCl in various pharmaceutical preparations.

Rapid determination of lidocaine solutions with non-column chromatographic diode array UV spectroscopy and multivariate calibration

A new method for the rapid determination of pharmaceutical solutions is proposed. A conventional HPLC system with a Diode Array Detector (DAD) was used with no chromatographic column connected. As eluent, purified water (Milli Q) was used. The pump and autosampler of the HPLC system were mainly utilised as an automatic and convenient way of introducing the sample into the DAD. The method was tested on the local anaesthetic compound lidocaine. The UV spectrum (245-290 nm) from the samples analysed in the detector was used for multivariate calibration for the determination of lidocaine solutions. The content was determined with PLS regression. The effect on the predictive ability of three factors: flow, data-collection rate and rise time as well as two ways of exporting a representative UV spectrum from the DAD file collected was investigated by means of an experimental design comprising 11 experiments. For each experiment, 14 solutions containing a known content of lidocaine were analysed (0.02-0.2 mg ml(-1)). From these 14 samples two calibration sets and two test sets were made and as the response in the experimental design the Root Mean Square Error of Prediction (RMSEP) values from the predictions of the two test sets were used. When the factor setting giving the lowest RMSEP was found, this setting was used when analysing a new calibration set of 12 lidocaine samples (0.1-0.2 mg ml(-1)). This calibration model was validated by two external test sets, A and B, analysed on separate occasions for the evaluation of repeatability (test set A) and determination over time (test set B). For comparison, the reference method, liquid chromatography, was also used for analysis of the ten samples in test set B. This comparison of the two methods was done twice on different occasions. The results show that in respect of accuracy, precision and repeatability the new method is comparable to the reference method. The main advantages compared with liquid chromatography are the much shorter time of analysis (<30 s) as well as the automatic and simple analytical procedure and the low consumption of organic solvents.

Colorimetric Determination of Benzocaine, Lignocaine and Procaine Hydrochlorides in Pure Form and in Pharmaceutical Formulations Using p-Benzoquinone

A simple, accurate and sensitive method for the microdetermination of benzocaine, lignocaine and procaine hydrochlorides in pure forms and in pharmaceutical formulations is described. The procedure is based on the reaction of those drugs in an aqueous acidic medium with p-benzoquinone to form charge-transfer complexes. The method has been used for the determination of 5.0-70, 5.0-60 and 5.0-90 microg ml(-1) of benzocaine, lignocaine HCl and procaine HCl, respectively. The complexes have apparent molar absorptivities of 1.70 x 10(3), 2.79 x 10(3) and 2.42 x 10(3) L mol(-1) cm(-1) and Sandell sensitivities of 9.72, 10.34 and 11.25 ng cm(-2), respectively. The proposed procedure of analysis is as accurate as the British Pharmacopoeial method (2003). The method was successfully used for the determination of those drugs in the presence of their degradation products, additives and excipients, which were normally encountered in pharmaceutical formulations.

Induction of olfactory mucosal and liver metabolism of lidocaine by 2,3,7,8-tetrachlorodibenzo-p-dioxin

Formulation of drugs for administration via the nasal cavity is becoming increasingly common. It is of potential clinical relevance to determine whether intranasal drug administration itself, or exposure to other xenobiotics, can modulate the levels and/or activity of nasal mucosal metabolic enzymes, thereby affecting the metabolism and disposition of the drug. In these studies, we examined changes in several of the major metabolic enzymes in nasal epithelial tissues upon exposure to the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), as well as the impact of these changes on the metabolism of a model intranasally administered drug, lidocaine. Results of these studies show that TCDD can induce multiple metabolic enzymes in the olfactory mucosa and that the pattern of induction in the olfactory mucosa does not necessarily parallel that which occurs in the liver. Further, increases in enzyme levels noted by Western blot analysis were associated with increased activities of several nasal mucosal enzymes as well as with enhanced conversion of lidocaine to its major metabolite, monoethyl glycine xylidide (MEGX). These results demonstrate that environmental exposures can influence the levels and activity of nasal mucosal enzymes and impact the pharmacology of drugs administered via the nasal route.

Comparison of HPLC and multivariate regression methods for hydrocortisone and lidocaine analysis of pharmaceutical preparations

A reverse-phase high-performance liquid chromatographic (HPLC) method to determine hydrocortisone acetate, hydrocortisone hemisuccinate and lidocaine is described in this paper. The separation was made in a LichrCART C(18) column using a methanol-NaH(2)PO(4)/Na(2)HPO(4) (0.1 mol L(-1)) (pH=4.5) buffer solution as a mobile phase in isocratic mode (60:40 (v/v)). The mobile phase flow rate and the sample volume injected were 1 mL min(-1) and 20 micro L, respectively. The detection was made with a diode-array detector measuring at the maximum for each compound. Quantification limits ranging from 0.18 to 0.84 micro g L(-1) were obtained when the peak area was measured. The method was applied in pharmaceutical formulations that were compared with those obtained by through multivariate regression spectrophotometry and micellar capillary electrophoresis (MEKC). HPLC results are in accordance with the results obtained by MEKC. The spectrophotometric method was suitable only for synthetic samples.

Development and validation of a reversed-phase liquid chromatographic method for the assay of lidocaine in aqueous humour samples

A simple, fast and reliable reversed-phase liquid chromatographic method was developed for the assay of lidocaine in human aqueous humour samples. The samples were analysed without any preliminary treatment on a C8 column with UV detection at 225 nm. The mobile phase consisted of methanol/sodium dihydrogen phosphate (30 mM) containing sodium pentansulphonate (10 mM) adjusted to pH 2.5 with phosphoric acid (50:50 v/v). Validation of the method showed it to be precise, accurate and linear over the concentration range of analysis with a limit of detection of 0.2 microgml(-1). The limit of quantitation was 2.5 microgml(-1) with a relative standard deviation of 2.5%. Linear regression analysis in the range 2.5-60 microgml(-1) gave correlation coefficients higher than 0.999. No interference from three commonly co-administered drugs was observed. The method developed was applied to the analysis of lidocaine in aqueous humour samples in order to evaluate and compare the efficacy of two different forms of administration of lidocaine for topical anaesthesia in cataract surgery.

Determination of lignocaine and amprolium in pharmaceutical formulations using AAS

The ion-associate complexes of lignocaine hydrochloride (Lig.Cl) with ammonium reineckate (Rk) or sodium cobaltithiocyanate, and that of amprolium hydrochloride (Amp.Cl) with ammonium reineckate, have been prepared. The precipitated ion-associates were subjected to elemental analyses, infrared and nuclear magnetic resonance spectroscopy and determination of the metal content for elucidation of their structures. The solubilities of the solid ion-associate complexes have been studied and their solubility products were determined at different temperatures at the optimum pH for their quantitative precipitation. The thermodynamic parameters DeltaH, DeltaG and DeltaS for the dissolution of the ion-associate complexes were calculated. These ion-associate complexes have been used for the quantitative determination of the above mentioned drugs by precipitating them with an excess of the inorganic metal complex ions and determining the excess metal complex ions using atomic absorption spectrometry. The method was applied for the determination of the above drugs in pure solution and pharmaceutical preparations. 0.135-135.4 and 0.158-157.6 mg of lignocaine and amprolium, respectively, can be determined with mean relative standard deviations (R.S.D.) 0.92-1.20% and recovery values of 99.18+/-0.48 to 100.12+/-0.34% indicating high precision and accuracy.

Simultaneous determination of tolperisone and lidocaine by high performance liquid chromatography

A reversed phase high performance liquid chromatographic (RP-HPLC) method for the simultaneous determination of tolperisone (TP) and lidocaine (LD) has been developed. The drugs were separated on a column (4.60 x 250 mm(2)) Spherisorb ODS (5 microm) using 5.5% triethylamine in 70/30 v/v acetonitrile/water as mobile phase 0.7 ml min(-1)and UV detection at 254 nm. The detection limits for Tolperisone hydrochloride (TP-HCl) and lidocaine hydrochloride (LD-HCl) were 0.20 ng/20 microl and 100 ng/20 microl and the quantitation limits were 0.50 ng/20 microl and 250 ng/20 microl, respectively. Linear calibration curves over the ranges of 1-10, 10-100 and 150-500 microg ml(-1) for TP-HCl and 10-500 microg ml(-1) for LD-HCl were established. Different calibration slopes were found for TP probably owing to changes in refractive index due to increase in TP concentration. The average recoveries of the added TP in the samples (TP-HCl tablets and injection liquid). A solutions spiked with standard TP-HCl were 99.9 and 99.7% with the RSD (n=11) of 0.66 and 0.67%, respectively. The average recovery of the added LD in the sample (injection) spiked with standard LD-HCl was 98.9% with the RSD (n=11) of 0.59%. The proposed method has been applied to the determination of TP-HCl and LD-HCl in commercial products available in Thailand. Comparative determination of TP by UV spectrophotometry and LD by colorimetry were also carried out. The results obtained by both methods were in good agreement of those obtained by the proposed method verified by using t-test. The proposed RP-HPLC method is simple, accurate, reproducible and suitable for routine analysis.

[Advances in solid phase microextraction coupled with high performance liquid chromatography]

Solid phase microextraction (SPME) is a solvent-free technique with high extraction efficiency and easy to perform automatically. It can be coupled with high performance liquid chromatography to perform efficient analysis of compounds with high polarity. The advances in solid phase microextraction coupled with high performance liquid chromatography, including its theory, interfaces, coating materials and applications, are reviewed with 36 references.

Retention of ionizable compounds on HPLC. 8. Influence of mobile-phase pH change on the chromatographic retention of acids and bases during gradient elution

The relationships between retention and mobile-phase pH in gradient elution are studied for acids and bases. The apparent pH shift caused by the increasing amount of acetonitrile and methanol has been determined starting from a wide range of pH values. It is shown that good relationships between the retention of ionizable compounds and the pH of the aqueous buffer can be established if the same type of buffer (ammonium acetate in this work) is used for all pH points. Equations are proposed to fit the gradient retention data to the pH of the aqueous buffer. The proposed equation gives an account of the relative variation of the pKa of the compound in the reference to the variation of the pH of the buffer as both parameters change during gradient elution.

ELISA for the quantification of pilsicainide

A sensitive and specific ELISA for an antiarrhythmic drug, pilsicainide, was developed, which is capable of measuring as low as 1.6 ng/ml. Anti-pilsicainide antibody was obtained by immunizing rabbits with pilsicainide conjugated with bovine serum albumin using diazotized N-(3-amino-2,6-dimethylphenyl)-8-pyrrolizidinylacetamide (3-aminopilsicainide). Enzyme labeling of pilsicainide with beta-D-galactosidase was similarly performed using a diazotized 3-aminopilsicainide. Cross-reactivity data showed that the antibody well recognizes both the aromatic ring and the pyrrolizidine moieties, and thus specific enough to the structure of pilsicainide. The values for the pilsicainide concentrations detected using this assay were comparable with those detected using HPLC. There was a good correlation between the values determined by the two methods. Moreover, the ELISA was about 30-fold more sensitive in detecting pilsicainide at lower concentrations. Using this assay, drug levels were easily measured in the serum of rabbits after oral administration of pilsicainide at a single dose of 1 mg/kg. The ELISA should be a valuable tool in therapeutic drug monitoring (TDM) and pharmacokinetic studies of pilsicainide.

Stability indicating HPLC method for the estimation of oxycodone and lidocaine in rectal gel

An HPLC method for the quantification of oxycodone and lidocaine in a gel matrix is described. The mobile phase consisted of methanol--water--acetic acid (35:15:1 v/v/v) and was delivered at 1.5 ml/min through a 4.6 x 250 mm Zorbax SB-C8 column. Oxycodone was detected at 285 nm and lidocaine at 264 nm. Linear calibration curves were obtained for oxycodone in the range of 0.05--1.5% (w/w) and for lidocaine in the range of 0.1--5.0% (w/w). Oxycodone and lidocaine were treated with hydrogen peroxide and the oxidation products were readily separated on the column. The method was applied to assess the stability of a gel containing oxycodone hydrochloride (0.3% w/w) and lidocaine (1.5% w/w). The gel was stored under refrigeration in ready-to-use syringes and under these conditions oxycodone and lidocaine were stable for at least 1 year. The gel is useful in the management of tenesmus in rectal cancer.

Determination of the content and identity of lidocaine solutions with UV-visible spectroscopy and multivariate calibration

A method is proposed for the determination of the content and identity of the active compound in pharmaceutical solutions by means of ultraviolet-visible (UV-Vis) spectroscopy, orthogonal signal correction (OSC) and multivariate calibration with soft independent modelling of class analogy (SIMCA) classification and partial least squares (PLS) regression. The content was determined with PLS regression and the identity with PLS regression and SIMCA classification. The method was tested on the local anaesthetic compound lidocaine. For the validation, external test sets of both manufactured sample solutions and samples from a stability study were used. For comparison with this new method, liquid chromatography was used as a reference method. The results show that in respect of accuracy, precision and repeatability, the new method is comparable to the reference method. The main advantage over liquid chromatography is the much shorter time of analysis and the simpler analytical procedure. An estimate of the analysis time saved with the proposed method compared with using liquid chromatography, together with practical considerations, is given.

Could local anesthesia while breast-feeding be harmful to infants?

BACKGROUND

Few studies have been carried out on the levels and possible toxicity of local anesthetics in breast milk after parenteral administration. The purpose of this study is to determine the amount of lidocaine and its metabolite monoethyl-glycinexylidide (MEGX) in breast milk after local anesthesia during dental procedures.

METHODS

The study population consisted of seven nursing mothers (age, 23-39 years) who received 3.6 to 7.2 mL 2% lidocaine without adrenaline. Blood and milk concentrations of lidocaine and its metabolite MEGX were assayed using high-performance liquid chromatography. The milk-to-plasma ratio and the possible daily doses in infants for both lidocaine and MEGX were calculated.

RESULTS

The lidocaine concentration in maternal plasma 2 hours after injection was 347.6 +/- 221.8 microg/L, the lidocaine concentration in maternal milk ranged from 120.5 +/- 54.1 microg/L (3 hours after injection) to 58.3 +/- 22.8 microg/L (6 hours after injection), the MEGX concentration in maternal plasma 2 hours after injection was 58.9 +/- 30.3 microg/L, and the MEGX concentration in maternal milk ranged from 97.5 +/- 39.6 microg/L (3 hours after injection) to 52.7 +/- 23.8 microg/L (6 hours after injection). According to these data and considering an intake of 90 mL breast milk every 3 hours, the daily infant dosages of lidocaine and MEGX were 73.41 +/- 38.94 microg/L/day and 66.1 +/- 28.5 microg/L/day respectively.

CONCLUSIONS

This study suggests that even if a nursing mother undergoes dental treatment with local anesthesia using lidocaine without adrenaline, she can safely continue breastfeeding.

Determination of lidocaine in dental pulp by high-performance liquid chromatography

The purpose of this study was to develop a method for lidocaine detection in dental pulp by high-performance liquid chromatography. The amounts of lidocaine in dog pulps were quantitated after local injection to evaluate lidocaine recovery from pulp tissue with this technique. Comparison was also made between the amount of lidocaine found in upper and lower canines. The high-performance liquid chromatography system was shown to be a reliable and reproducible tool for lidocaine determination. Lidocaine extraction from the tissue showed recovery of 90%. The amount of lidocaine recovered from the upper canine (0.21 microg/mg) was higher than the lower canine (0.17 microg/mg).