Xylazine toxicity--literature review and report of two cases.

Xylazine is a veterinary sedative, analgesic or general anesthetic. Its pharmaceutical action results in sympathetic discharge via stimulation of alpha-2-adrenoceptors. In humans, toxicity consists of central nervous system depression, bradycardia and hypotension. The dosages known to produce toxicity in humans vary from 40 mg up to 2400 mg. Because of decomposition, xylazine blood concentrations in two homicide victims were unknown; however, the concentrations in the brain, liver, and kidneys were much higher in the 23-year-old female versus the 33-year-old male victim. A bottle of xylazine found on the crime scene had a concentration of 100 mg/mL. This 50 mL bottle had 32 mL remaining. Therefore at some point in time 18 mL had been utilized. The amount of available milligrams of xylazine (1800 mg) were enough to cause toxicity in both the woman and the man. Of interest was the fact that the partially skeletonized heads were found remote from the torsos, however, the concentration of xylazine in the body tissues provided a toxicological match of which head belonged to which body. Xylazine toxicity in humans and its relationship to these homicides will be the focus of this report.

Identification and quantitation of ibogaine and an o-demethylated metabolite in brain and biological fluids using gas chromatography-mass spectrometry.

This report describes a sensitive method for quantitating ibogaine and a single major metabolite in biological fluids and brain tissue. We identified the metabolite as 12-hydroxy-ibogamine (12-OH-ibogamine or noribogaine) by full-scan, electron-impact gas chromatography-mass spectrometry (GC-MS). Ibogaine, 12-OH-ibogamine, and o-(methyl)-ibogaine-d3 (ibogaine-d3) internal standard were isolated by solvent extraction under basic conditions. The resulting organic extract was evaporated to dryness, and the residue was derivatized at room temperature with ethyl iodide in the presence of trimethyl anilinium hydroxide in dimethyl sulfoxide. The reaction was terminated by acidification and washed with organic solvents to remove impurities. The aqueous phase was then alkalinized and reextracted. The organic extract was concentrated and analyzed by GC-MS. Quantitation was based upon the ratios of the molecular ions at m/z 310 for ibogaine, m/z 313 for ibogaine-d3, and m/z 324 for 12-OH-ibogamine ethyl ether. The limit of detection was 5 ng/mL for both ibogaine and derivatized 12-OH-ibogamine, and limits of quantitation were between 5 and 10 ng/mL for all matrices tested. Calibration curves were linear in the range of 3-1000 ng/mL or ng/g for both analytes.

m-Hydroxybenzoylecgonine: an important contributor to the immunoreactivity in assays for benzoylecgonine in meconium.

Meconium has been reported to be a more suitable specimen than maternal or neonatal urine for detecting fetal exposure to cocaine. In a study comparing various immunoassays with gas chromatography/mass spectrometry (GC/MS), several unexplained discrepancies among the assays were noted. Using methanol extracts of meconium samples, an immunoreactive spot that was more polar than benzoylecgonine was detected by thin-layer chromatography (TLC). An extract of this spot analyzed by GC/MS yielded a fragmentation pattern indicative of an aryl hydroxylated benzoylecgonine. Standards of m-hydroxybenzoylecgonine, o-hydroxybenzoylecgonine, and p-hydroxybenzoylecgonine were synthesized; it was determined that m-hydroxybenzoylecgonine had the same retention time and ion ratios as the TLC immunoreactive spot. Furthermore, m-hydroxybenzoylecgonine proved to be immunoreactive. Ten meconium samples immunoreactive for benzoylecgonine were analyzed by GC/MS. Results before and after hydrolysis with beta-glucuronidase (type IX) showed free m-hydroxybenzoylecgonine comprising 59 to 94% of the total m-hydroxybenzoylecgonine and showed total m-hydroxybenzoylecgonine values ranging from 0.2 to 6.3 times as high as benzoylecgonine. Therefore, m-hydroxybenzoylecgonine appears to be a quantitatively important cocaine metabolite in meconium, which is responsible for a significant portion of the discrepancy between benzoylecgonine concentrations in meconium extracts as measured by immunoassay and GC/MS.

Stereochemistry of the human macular carotenoids.

PURPOSE: To complete identification of the major components of the human macular pigment. METHODS: Chemical ionization mass spectra of the macular pigment components were obtained and compared with those of zeaxanthin and lutein standards. A comparison was also made using chiral column high-performance liquid chromatography, which is capable of resolving individual stereoisomers of these carotenoids. Zeaxanthin and lutein from human blood plasma were similarly analyzed. RESULTS: The mass spectrometry data supported earlier work in which high-performance liquid chromatography, UV-visible spectrometry and chemical modification showed that the macular pigment comprises two carotenoids with identical properties to those of zeaxanthin and lutein. Chiral column chromatography showed that the "zeaxanthin" fraction is a mixture of two stereoisomers, zeaxanthin itself [(3R,3'R)-beta,beta-Carotene-3,3'-diol] and meso-zeaxanthin [(3R,3'S)-beta,beta-Carotene-3,3'-diol]. The other fraction is the single stereoisomer, lutein [(3R,3'R,6'R)-beta,epsilon-Carotene-3,3'-diol]. In human blood plasma, only zeaxanthin and lutein were found. CONCLUSIONS: The results strongly suggest that meso-zeaxanthin results from chemical processes within the retina. Noting that lutein exceeds zeaxanthin in plasma but that the combined zeaxanthin stereoisomers exceed lutein in the retina, the possibility was considered that meso-zeaxanthin is a conversion product derived from retinal lutein. Under nonphysiologic conditions, the authors demonstrate that a base-catalyzed conversion of lutein to zeaxanthin yields only the meso-(3R,3'S) stereoisomer.

Analysis of cocaine and cocaethylene in blood and tissues by GC-NPD and GC-ion trap mass spectrometry.

Cocaethylene, the ethyl homolog of cocaine, is an active cocaine metabolite found in cocaine users who simultaneously consume cocaine and ethanol. To study the combined incidence of cocaine and cocaethylene, an analytical method was devised that would simultaneously quantify both drugs in whole blood or tissues. The method includes a quantitative procedure by GC-NPD with a confirmation by ion trap mass spectrometry. Propylbenzoylecgonine, the propyl homolog of cocaine, was used as the internal standard. The quantitative method was linear from 0.05 to 10.0 mg/L with a limit of detection of 0.02 mg/L. Cocaethylene and propylbenzoylecgonine were synthesized in the laboratory. The complete analytical procedure and the method of synthesis are presented, along with brief descriptions of medical examiner cases where both cocaine and cocaethylene were quantified and where cocaethylene may have played a part in the cause of death. In the five cases presented, the cocaine concentration ranged from 0.03 to 1.4 mg/L and cocaethylene ranged from 0.03 to 0.53 mg/L in the blood.

The use of hair analysis to document a cocaine overdose following a sustained survival period before death.

Hair analysis for cocaine was used in the investigation of a case of accidental cocaine poisoning. A 25-year-old man consumed an entire bottle of Pony Malta, an imported Colombian soft drink. Unbeknownst to him, the 6.2-oz bottle contained a large quantity of cocaine. It was subsequently discovered that this bottle was one of 45 recovered that contained cocaine as part of a smuggling scheme. The subject was hospitalized for acute cocaine intoxication but died 24 days later. The admission blood contained 2.3 mg/L of cocaine and 4.5 mg/L of benzoylecgonine. Subsequent segmental analysis by MS/MS of hair samples taken at the autopsy revealed a peak cocaine concentration in the segment corresponding to the time he ingested the tainted beverage. The use of hair analysis as an adjunct to traditional analytical techniques may help document drug use history and is especially useful in situations have blood and urine specimens have not been collected in a timely fashion.

Cocaethylene: a unique cocaine metabolite displays high affinity for the dopamine transporter.

Concurrent cocaine and alcohol use is common practice in the general population, as indicated by recent prevalence studies. In the presence of ethyl alcohol, cocaine is metabolized to its ethyl homolog, cocaethylene. The transesterification of cocaine and ethanol to cocaethylene takes place in the liver and represents a novel metabolic reaction. Cocaethylene was detected in postmortem blood, liver, and neurological tissues in concentrations equal to and sometimes exceeding those of cocaine. In vitro binding studies demonstrate that cocaethylene has a pharmacological profile similar but not identical to that of cocaine at monoamine transport sites assayed in the human brain. Cocaethylene was equipotent to cocaine at inhibiting [3H]mazindol binding to the dopamine transporter. The blockade of dopamine reuptake in the synaptic cleft by cocaethylene may account for the enhanced euphoria associated with combined alcohol and cocaine abuse.

Identification of basic drugs in urine by dual fused silica capillary column GC.

A method for analyzing urine for the presence of basic drugs and their metabolites using two fused silica capillary columns is described along with operating conditions and column characteristics. Urine extracts were injected into a gas chromatograph equipped with nitrogen phosphorous detectors (GC/NPD) and two capillary columns, housed in a single injection port. The injected material was simultaneously chromatographed in each column. Identification of unknowns was done using relative retention times.