Determination of lidocaine in postmortem fluids and tissues

Simultaneous determination of local anesthetics including ester-type anesthetics in human plasma and urine by gas chromatography-mass spectrometry with solid-phase extraction

The present study describes the simultaneous determination of seven different kinds of local anesthetics and one metabolite by GC-MS with solid-state extraction: Mepivacaine, propitocaine, lidocaine, procaine (an ester-type local anesthetics), cocaine, tetracaine (an ester-type local anesthetics), dibucaine (Dib) and monoethylglycinexylidide (a metabolite of lidocaine) were clearly separated from each other and simultaneously determined by GC-MS using a DB-1 open tubular column. Their recoveries ranged from 73-95% at the target concentrations of 1.00, 10.0 and 100 microg/ml in plasma, urine and water. Coefficients of variation of the recoveries ranged from 2.3-13.1% at these concentrations. The quantitation limits of the method were approximately 100 ng/ml for monoethylglycinexylidide, propitocaine, procaine, cocaine, tetracaine and dibucaine, and 50 ng/ml for lidocaine and mepivacaine. This method was applied to specimens of patients who had been treated with drip infusion of lidocaine, and revealed that simultaneous determination of lidocaine and monoethylglycinexylidide in the blood and urine was possible.

Distribution of drugs in various tissues in a brain dead man

We examined the distribution of drugs in a 49-year-old brain-dead man. Our objective was to determine the possibility of diagnosing how and at what point the patient became brain dead. The presence of mepivacaine, pentazocine, lidocaine and thiamylal in various tissues, including seven regions of the brain were confirmed, using gas chromatography/mass spectrometry. Tissue-to-blood concentration ratios of mepivacaine, pentazocine and lidocaine in the brain were higher than these ratios in other tissues, while ratios of thiamylal were lower. Therefore, cerebral blood flow was likely to have ceased between the administration of the former drugs and that of the latter drug, in agreement with clinical records. Among seven regions of the brain, the ratios of the former three drugs were high in occipital and parietal lobes, and were low in the cerebellum and medulla oblongata. On the other hand, the ratios of the latter drug were high in the cerebellum and the medulla oblongata. Therefore, cerebral blood flow presumably ceased first in occipital and parietal lobes, and last in the cerebellum and the medulla oblongata. Based on these results, assessment of concentrations of drugs in human tissues, including various regions of brain is useful to determine the time and progression of brain death.

Positive and negative ion mass spectrometry and rapid isolation with Sep-Pak C18 cartridges of ten local anaesthetics

The positive ion electron impact (PIEI), positive ion chemical ionization (PICI) and negative ion chemical ionization (NICI) mass spectra and a rapid isolation procedure using Sep-Pak C18 cartridges are presented for ten local anaesthetics. In the PIEI mode, molecular peaks were very small or missing for most compounds. Peaks at m/z 86 due to the diethylaminoethyl or propylaminoethyl group constituted base peaks in six compounds. In the PICI mode, peaks due to M + H and M + C2H5 appeared. The cation at m/z 86 was also observed for the six compounds. This ion seems useful for the screening of local anaesthetics. In the NICI mode, anions at m/z M - H constituted base peaks for all compounds, peaks at m/z M + 12 appeared in many compounds. The total ion current in the PIEI and PICI modes generally gave higher sensitivity than in the NICI mode. Local anaesthetics present in whole blood or cerebrospinal fluid (CSF) could be rapidly isolated by use of Sep-Pak C18 cartridges with chloroform/methanol as an elution solvent. Their detection was possible using wide-bore capillary gas chromatography with SPB-1 and HP-17 wide-bore capillary columns with satisfactory separation from impurities.

High performance liquid chromatographic measurement of lignocaine in tissue samples following transabdominal placental biopsy

A method is described for the measurement of lignocaine in small samples of fetal and placental tissue. Tissue samples (ca 100 mg) are digested using a preteolytic enzyme. Lignocaine and an internal standard are extracted into methyl tert-butyl ether and analysed by high-performance liquid chromatography with electrochemical detection (+1.0 V vs Ag/AgCl). The limit of accurate measurement is better than 0.1 mg/kg wet weight for a 100 mg sample. This method has been used to assess fetal exposure to the drug when used as a local anaesthetic during transabdominal placental biopsy (chorionic villus sampling). The range of lignocaine concentrations found in the tissue samples was large (from less than 0.04 mg/kg wet weight to 15.4 mg/kg wet weight) although most samples contained less than 1.0 mg lignocaine/kg wet weight.

Cocaine abuse and violent death

One hundred and fourteen Los Angeles County Coroner's cases found to be positive in drug screening for the presence of cocaine were studied to determine the relationship between cocaine abuse and violent death. Of these 114 victims, 70 (61.4%) died a violent death--over 68% of these as shootings and stabbings. Fourteen of the violent death victims (20%) were found to have been behaving in a violent manner just prior to their death. Violence seems to be clearly connected to the use and abuse of cocaine.

Distribution of lidocaine and disopyramide in human blood and tissue, a case report of death caused by spinal anesthesia

An 11-year-old girl was anesthetized with hyper-baric solution of lidocaine as spinal anesthesia for an appendectomy in a surgical clinic. Respiratory arrest which occurred soon after the injection, was not discovered for a period of time. Since spontaneous respiration recovered within 2 h of intensive resuscitation, the patient was transferred to a community hospital for intensive care. Ten hours after the spinal anesthesia, she died of cardiac failure. The concentration of lidocaine in the brain was 5-10 times more than that in other tissues. The relationship between the possibility of malpractice of spinal anesthesia and tissue distribution of the drug was discussed. In addition to lidocaine, a toxic amount of disopyramide, an antiarrhythmic drug, was detected in the body. The distribution of disopyramide was also estimated, and the pharmacokinetics of disopyramide in plasma and tissues were studied experimentally in rats.

Studies on the distribution of lidocaine in tissue after spinal and intravenous application in rabbits: clinical and forensic toxicological aspects

Distribution of lidocaine in tissue was investigated after spinal anesthesia and intravenous application in rabbits to examine aspects of forensic and clinical toxicology. Respiratory arrest occurred at 5-15 min after injection of 5 mg/kg hyper-baric lidocaine solution into the subarachnoid space followed by standing in the head down position. The minimum concentration of lidocaine in the middle part of the cervical spinal cord of the dead rabbits was 197 micrograms/g. On the other hand, maximum concentration in the same site at the critical state of almost complete respiratory arrest was 175 micrograms/g. The time at which the concentration of lidocaine reached a maximum in plasma and various tissues after subarachnoid administration was 10-15 min. The concentrations in the lumbar spinal cord, a site of administration, were 1200-1500 micrograms/g 5 min after the injection, which decreased gradually to about 180-250 micrograms/g at 60 min when paralysis of the hind legs began to recover. According to these data, the concentration of lidocaine in the spinal cord of rabbits required for neural blockade was presumed to be about 200 micrograms/g. Since the maximum concentrations of lidocaine in each tissue was already observed at 2.5 min after intravenous injection, transport of lidocaine from plasma to tissues was considered to be very rapid. Lidocaine accumulates most rapidly in the spleen and kidney, followed by the brain, lung, heart, spinal cord and plasma. The concentration in the liver was the least because of its hepatic metabolism. Distribution to adipose tissue was slower than that to other tissues, but the highest accumulation was observed at the late stage. Elimination rates of plasma and tissues other than adipose were almost the same.

Quantitative analysis of common anaesthetic agents

A summary of chromatographic (e.g. gas chromatography, high-performance liquid chromatography) and non-chromatographic (e.g. radioimmunoassay, enzyme-multiplied immunoassay) analytical techniques suitable for the quantitative analysis of the most popular inhalational (halothane, methoxyflurane, enflurane, isoflurane and nitrous oxide), intravenous (barbiturate, benzodiazepines, etomidate, althesin, morphine, fentanyl, alfentanil, sufentanil, droperidol and ketamine) general and amide-type local (lidocaine, mepivacaine, etidocaine and bupivacaine) anaesthetic agents and some of their metabolites, in biological material, is described. In the case of inhalational anaesthetics attention is also payed to pollution measurement and breath-to-breath monitoring.