Gary W. Kunsman

Tissue Distribution of Ketamine in a Mixed Drug Fatality

While reports of ketamine abuse are increasing, reports of ketamine deaths and tissue concentrations associated with fatalities are rare. We report here a case of a mixed drug fatality involving ketamine and ethanol. Ketamine analysis was carried out by gas chromatography with a nitrogen-phosphorus detector (NPD). We found the following tissue concentrations: blood 1.8 mg/L; urine 2.0 mg/L; brain 4.3 mg/kg; spleen 6.1 mg/kg; liver 4.9 mg/kg, and kidney 3.6 mg/kg. The blood ethanol concentration was 170 mg/dL. Because an empty nalbuphine ampule was found in the possession of the deceased, the blood was assayed for this opioid compound using a gas chromatography/mass spectrometry (GC/MS) method. None was detected at a limit of detection of 0.02 mg/L.

Mefloquine distribution in postmortem cases

Mefloquine is currently the drug-of-choice for malaria prophylaxis among military personnel. Four active duty military personnel receiving 250 mg mefloquine per week were killed in the line of duty under combat conditions. Samples of blood, bile, liver, kidney, muscle, brain, spleen and lung were submitted to the Division of Forensic Toxicology, Office of the Armed Forces Medical Examiner, for routine toxicologic analysis. Qualitative screening revealed only the presence of ethanol (< 25 mg/dl, probably attributable to postmortem formation) and mefloquine. Quantitation of mefloquine was performed using an HP 5880 gas chromatograph equipped with a nitrogen/phosphorus detector. The column was an HP-5 cross-linked 5% phenyl methyl silicone fused silica capillary column (15 m x 0.25 mm i.d. x 0.25 microns film thickness). The temperature program began at 110 degrees C, was held for 1 min and ramped at 20 degrees C/min to 200 degrees C, held for 1 min and then ramped at 10 degrees C/min to 280 degrees C and held for 10 min. Mefloquine elutes with a relative retention time similar to that of the tricyclic antidepressants. No postmortem data concerning mefloquine concentrations or tissue distribution was available. Quantitated blood concentrations in the presented cases were greater than the expected therapeutic values indicating the possibility of postmortem redistribution of this drug. No mefloquine overdoses were identified in the literature making comparison to the postmortem therapeutic concentrations impossible at this time.

Gas chromatographic procedures for determination of ethanol in postmortem blood using t-butanol and methyl ethyl ketone as internal standards

Three gas chromatographic procedures for the determination of ethanol in postmortem blood using alternative internal standards to n-propanol are presented: a direct injection procedure using t-butanol, and two headspace methods using t-butanol and methyl ethyl ketone. t-Butanol and methyl ethyl ketone were well resolved from ethanol, acetone, methanol and other commonly observed putrefactive volatiles using direct injection or headspace analysis. CVs for the direct injection method were below 5% for ethanol and below 10% for the other volatiles. The lower limits of detection (LOD) were 25-50 mg/L. The CVs for the headspace methods were below 5% for ethanol and below 6% for the other volatiles. The LODs were 10 mg/L using either t-butanol or methyl ethyl ketone as internal standards. The use of t-butanol or methyl ethyl ketone as alternatives to n-propanol avoids the possibility of error in the quantitation of ethanol due to the presence of n-propanol and allows for the identification of other volatiles that may aid in distinguishing antemortem ingestion from postmortem production of ethanol.

Methodologic considerations in the interpretation of postmortem carboxyhemoglobin concentrations

The interpretation of postmortem carboxyhemoglobin (COHb) concentrations can have major implications even when COHb is not the direct cause of death. Much litigation may hinge on the length of time an individual was alive during the fire. Therefore, the reliability of an analytical method to measure COHb, ranging from low to sub-lethal levels, is critical to the proper interpretation of results. This study used 40 blood specimens from fire deaths and 15 blood specimens from non-fire deaths to compare COHb levels obtained from a spectrophotometric method (IL 482 CO-Oximeter; CO-Ox) with a reference gas chromatographic method (GC). Since spectrophotometric methods are influenced by the amount of total hemoglobin (Hb) present in the blood, multiple saline dilutions of specimens were performed to yield Hb as low as 1g/dl. For GC COHb concentrations < 5% and Hb > or = 4g/dl, the average and median ratios of CO-Ox COHb to GC COHb concentrations were 2.8 and 2.6 respectively. These ratios were 8.0 and 6.8 respectively when Hb < 4g/dl. At GC COHb levels ranging from 5 to 40% and Hb > or = 4g/dl, the average and median ratios were 1.6 and 1.0 respectively. These ratios were correspondingly 2.1 and 1.9 when Hb < 4 g/dl. These data clearly indicate COHb can be influenced by the analytical methods used.

A mixed-drug intoxication involving venlafaxine and verapamil.

This case report describes the suicide of a 52-year-old woman whose cause of death was attributed to a mixed-drug intoxication involving venlafaxine and verapamil. Venlafaxine is prescribed for the treatment of depression and should be used with caution in patients with cardiovascular disease. Verapamil is a calcium channel blocker primarily used for treatment of cardiovascular disorders. The following drug concentrations were determined in postmortem fluids: verapamil--3.5 mg/L (femoral blood), 9.4 mg/L (subclavian blood), and 1.0 mg/L (vitreous fluid); norverapamil--1.0 mg/L (femoral blood), 2.1 mg/L (subclavian blood), and 0.20 mg/L (vitreous fluid); verapamil and norverapamil could not be detected in bile or urine due to the high levels of erythromycin present; venlafaxine--6.2 mg/L (femoral blood), 8.6 mg/L (subclavian blood), 5.3 mg/L (vitreous fluid), 54.0 mg/L (bile), and 72.3 mg/L (urine); and O-desmethylvenlafaxine--5.4 mg/L (femoral blood), 8.3 mg/L (subclavian blood), positive (vitreous fluid), 29.2 mg/L (bile), and 9.5 mg/L (urine). The cause of death was determined to be a mixed-drug intoxication resulting from an overdose of verapamil and venlafaxine. The manner of death was determined to be suicide.

A comparison of ethanol concentrations in the occipital lobe and cerebellum

While many publications have addressed the issue of ethanol concentration in brain tissue as a better indicator of impairment than blood alcohol concentration (BAC), very few have looked at the regional distribution of ethanol in the brain and its possible significance in postmortem sampling. This paper reports on the analysis of occipital pole and cerebellar hemisphere for ethanol in 25/brain samples obtained at autopsy from the brain collection of the National Institutes of Mental Health/Stanley Foundation. When available, these concentrations were compared to BAC. The average ratio of occipital lobe alcohol concentration (OAC) to BAC for cases which also had blood samples (18/24) was 0.9, SD = 0.5, with a range of 0-1.8; the average ratio of cerebellar alcohol concentration (CAC) to BAC for these cases was 0.6, SD = 0.4, range = 0-1.2. When only those cases with a BAC > or = 0.04 g/dl (14/18 cases) were considered, the average OAC/BAC and CAC/BAC ratios were 0.8 (SD = 0.4) and 0.7 (SD = 0.4), respectively. These distribution ratios are well within the ranges reported by other authors and do not significantly differ from each other. The cortical brain region available or selected for postmortem ethanol analysis is probably not critical.

VITAMIN B2 INTERFERENCE WITH TDX DRUGS-OF-ABUSE ASSAYS

Migraine is a headache condition found in significant frequency in the general population. One recent study has shown that riboflavin, Vitamin B2, is an effective prophylactic treatment for this headache condition. One subject in a recent study conducted by the Division of Forensic Toxicology, Armed Forces Institute of Pathology (AFIP) was taking 200 mg of riboflavin twice daily for the prevention of migraine headaches. When that subjects urine was tested using Abbott TDx drugs-of-abuse assays a number of tests resulted in a MX BKG error and all samples had BLK I values greater than those observed with normal urine specimens. The MX BKG error occurs when the BLK I value is greater than the upper limit determined by the manufacturer for a particular assay. High BLK I values may result if the specimen being analyzed contains a fluorophore that will compete with the fluorescein-labeled antibody used in the assay. This error serves as a notification that an interfering substance may be present and the assay is not performing according to manufacturer-specifications. Upon termination of riboflavin therapy the subjects BLK I values began to decrease within 60 h of the last 200 mg dose. A second subject began chronic riboflavin use to confirm this interferent effect. Elevated BLK I values resulted within 3 h of a single 200 mg dose and MX BKG errors occurred 1 h after a second 400 mg dose. No false negative results were noted with either subject (both subjects used butalbital and the first subject also used hydrocodone and diazepam during the study), suggesting that riboflavin is not an adulterant. Riboflavin use, however, does interfere with the TDx DAU assays and may result in quantitative values being determined which are of questionable validity in the face of an elevated BLK I value or may result in only an MX BKG error and no quantitative value reported. It is unclear if the interfering fluorophore is simply riboflavin itself or a combination of riboflavin and its metabolic products. Results obtained on urine samples collected from individuals using prophylactic riboflavin for migraine prevention and analyzed by TDx may be of questionable validity. Such samples may require analysis utilizing another immunoassay technique that does not employ a fluorescein-labeled antibody.