Cocaine Related Deaths
Content
Forensic Science International 176 (2008) 121–123 www.elsevier.com/locate/forsciint
Cocaine-related deaths: An enigma still under investigation
Elisabetta Bertol a,*, Claudia Trignano b, Maria Grazia Di Milia a, Marianna Di Padua a, Francesco Mari a
a
Forensic Toxicology Division, Department of Anatomy, Histology and Legal Medicine, University of Florence, Italy b Institute of Legal Medicine, University of Sassari, Italy Received 20 December 2006; received in revised form 23 July 2007; accepted 24 July 2007 Available online 30 August 2007
Abstract In recent years there has been an increase interest in cocaine-related death reflecting the rising trend in cocaine use in Europe. Nevertheless is still now very difficult to attribute a death to cocaine. We can affirm that cocaine can be responsible for the cause of death only when there is a reasonably complete understanding of the circumstances or facts surrounding the death. Isolated blood cocaine levels are not enough to assess lethality, should be always considered and evaluated in relation to concentrations of cocaine and benzoylecgonine concentrations in body tissue compartments, especially in brain and blood. We have reanalyzed all of our cocaine-related case from 1990 to 2005, applying the methodology used by Spielher and Reed over 30 years ago. Our aim was to try to validate this model and verify its applicability and effectiveness after 20 years. # 2007 Elsevier Ireland Ltd. All rights reserved.
Keywords: Cocaine; Cause of death; Cocaine-related cases
1. Introduction Except in the case of massive drug exposure (courier or ‘‘body packers’’), where acute toxicity is dose-related and is characterized primarily by its sympathomimetic effects (tachycardia, hypertension and hyperthermia arrhythmias) [1], cocaine-related deaths occur for the major part after prolonged drug use. Long term use of cocaine initiates a series of changes at molecular, cellular and tissue levels [2], many of which favour the occurrence of sudden cardiac death. However, because the cause of death in these cases is not dose-related (except in trivial sense of prolonged usage of large amount), demonstration of the presence of cocaine in fluids or tissues is not sufficient to prove that death was due to cocaine [3]. The criteria for the identification of deaths caused by cocaine intoxication, as for other types of drug deaths, are (1) a review of investigative findings, followed by (2) a complete autopsy, and (3) the identification, confirmation and
* Corresponding author at: Istituto di Medicina Legale, Dipartimento di Anatomia, Istologia e Medicina Legale, Policlinico Careggi, Viale Morgani no. 85, 50134 Firenze, Italy. Tel.: +39 0557947208; fax: +39 0557947208. E-mail address: elisabetta.bertol@unifi.it (E. Bertol). 0379-0738/$ – see front matter # 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.forsciint.2007.07.011
quantification of cocaine and/or its metabolites in samples taken from the cadaver [4]. The literature offers considerable toxicological data about cocaine-related deaths [5–9], and it is clear that correlation of a specific blood or tissue concentration with toxicity is not generally possible. For some authors, establishing the presence of cocaine in the blood, in the absence of other findings, may signify death by cocaine poisoning, but others would undoubtedly insist that isolated cocaine levels cannot be used to explain the cause of death. In fact the presence of low levels of cocaine are proof only of cocaine use, if the appropriate anatomical or histological changes are present, cocaine may be the cause of death even if it is not detectable in the blood. This reality explains why it is impossible to correlate a specific blood concentration to toxicity and also why trying to establish a concept of minimum fatal concentration for cocaine is a futile and inappropriate exercise. The interpretation of toxicological findings in cocaineassociated deaths is complicated by various factors including route of administration, continued absorption after death, different metabolism in chronic or occasional user (the half life of cocaine is considered to be about one-half to one and onehalf hours while in chronic users there is some evidence that it
122
E. Bertol et al. / Forensic Science International 176 (2008) 121–123 361, 346); Nalorfine (455, 414, 440, 324)]. The oven temperature was programmed in the range 60 (2 min)–300 (4 min)8C, at 30 8C/min. The injector was temperature-programmed at 300 8C. Carrier gas: He 20 ml/min flow rate.
may be significantly longer than this. The half-life of benzoylecgonine does not appear to be the same in both acute or chronic users); [10] however in vitro degradation of both parent drug and metabolite may occur over time, especially, when stored at ambient temperature even when the blood is stored in tubes with preservatives. Autopsy must be performed within 24–48 h of death with the body stored at 4 8C for much of the time and blood specimens must be refrigerate until analysis [11], in order to minimize the effects of post-mortem redistribution of cocaine and its major metabolite, benzoylecgonine (the drug is sequestered to some extent in tissue such as the heart muscle and therefore has the potential to be released into the blood during the post-mortem interval). Heart blood should never be used for toxicological evaluation. Cocaine freely and rapidly crosses the blood brain barrier, but benzoylecgonine does not cross at all. It follows that any benzoylecgonine detected in the brain was produced in the brain, and not transported from elsewhere. Supposing that post-mortem blood concentrations of cocaine and its metabolites cannot be used to predict the interval between the last administration and death, given that the brain is the best matrix for cocaine analysis because cocaine concentrations found in post-mortem blood may not be representative of the concentrations existing at the time of death, Spielher and Reed [12] have investigated the interpretative value of the determination of cocaine and benzoylecgonine in blood and brain tissue and their correlation. Since in our Forensic Toxicology Division all suspected cocaine cases (overdoses and incidental deaths) were always investigated for cocaine and its metabolites distribution in biological fluids and tissues, we wanted to apply the Spielher and Reed model to our cocaine-related cases from 1990 to 2005. Our aim was to try to validate this model and verify its applicability and effectiveness after 20 years.
2. Materials and methods
We work with data obtained from analysis of blood and brain on 84 ascertained cases identified as cocaine overdose fatalities (considering toxicological analysis, all context of death circumstances, autopsy and histological findings), and on 33 cases where cocaine was incidental to the cause of death. During the years every sample has been analyzed with the following method.
2.2. Sample preparation
Post-mortem brain tissue and blood samples, removed at autopsy, were stored at À80 8C until analysis. Brain tissue (1 g) and blood (1 ml) were added to distilled water (4 ml), plus the internal standard (1 ml nalorfine at 1 mg/ml concentration), potassium phosphate buffer 0,1 M (pH 6) (2 ml). The sample was mixed with a vortex shaker, centrifuged and filtrated.
2.3. Extraction procedure
To prepare the solid phase extraction column (Bond Elut Certify SPEVARIAN (Harbor City, California, USA), 2 ml of methanol and 2 ml of potassium phosphate buffer were passed through the column without allowing the solvent to dry. The sample was then applied to the column and drawn through. The column was washed with 2 ml of distilled water, 3 ml of hydrochloric acid and 5 ml of methanol and then allowed to dry for 5 min at full vacuum. Finally, 3 ml of elution solvent (methylenechloride: isopropanol [80:20] at 2% ammonium hydroxide) was added to the column and allowed to pass through by gravity. The eluate was collected and evaporated at room temperature.
2.4. Derivatisation
The residue from evaporation of the extract was reconstituted with 50 ml of MSTFA (Sigma–Aldrich Chemie Steinheim, Germany). The mixture was then heated to 75 8C for 15 min in a heating block and 1 ml aliquot was injected into the GC/MS.
2.5. Quantitative analyses
Quantification was performed by construction of five-point calibration curve prepared by spiking drug-free blood and homogenized brain at the following final concentration: 0.05, 0.2, 0.5, 1 and 2 mg/ml. A good linear regression was obtained (y = 0.185x + 1.32, R2 = 0.965, blood; y = 0.611x + 2.75, R2 = 0.972, brain). Accuracy and inter-day precision (calculated as relative standard deviation and bias) were always better than 12%. According to validation results the lower limit of quantification (LLOQ) was determined to be 0.05 mg/ml.
3. Results Results obtained from analysis of cocaine and benzoylecgonine concentrations in blood and brain, and their ratios, on overdose and incidental finding in our cocaine-related case from 1990 to 2005, were resumed in Tables 1 and 2. 4. Discussion and conclusions Spielher and Reed, in their study, found that in 37 autopsied cases of cocaine-related deaths (overdose) the mean cocaine/
2.1. Instrumentation
Extracts were analyzed in a Thermoquest Trace GC/Finningan Polaris Q MS, equipped with a 12 m  0.2 mm i.d. phenylmethylsilicone 5% (5 MS) capillary column with a 0.33 mm film thickness. The instrument was used in the full scan electron ionization mode, scanning m/z in the range 75–500 and in the acquisition SIM mode [Cocaine (182, 82, 303, 272); Benzoylecgonine (82, 240, Table 1 Cocaine/B.E. ratios in blood and brain Fatalities
Coca/B.E. ratio, mean Æ S.D. Blood Brain 10.28 Æ 5.79 0.71 Æ 0.61 14.70 0.87
Forensic Tox Division, Florence, 1990–2005 Spiehler and Reed [12]
Overdose (84 cases) Incidental (33 cases) Overdose (37 cases) Incidental (46 cases)
0.69 Æ 0.53 0.21 Æ 0.15 0.64 0.27
E. Bertol et al. / Forensic Science International 176 (2008) 121–123 Table 2 Brain/blood ratios for cocaine and benzoylecgonine Fatalities Brain/blood ratio, mean Æ S.D. Cocaine Forensic Tox Division, Florence, 1990–2005 Spiehler and Reed [12] Overdose (84 cases) Incidental (33 cases) Overdose (37 cases) Incidental (46 cases) 8.06 Æ 4.45 2.28 Æ 1.23 9.60 2.50
123
Benzoylecgonine 0.67 Æ 0.47 1.67 Æ 0.93 0.36 1.40
benzoylecgonine concentration ratio in the brain is always ten or more times higher than in the plasma, whereas where cocaine was only an incidental finding (46 case instances of murder, accidental death, etc.), the cocaine/benzoylecgonine concentration ratio in the brain was only three or four times higher than in the plasma. Our findings were in agreement with those of the Spielher and Reed studies. In fact we found that in overdose cases the mean ratios of cocaine/benzoylecgonine in the brain were 10.28 and in the blood 0.69, and were clearly different from those found in incidental cases (brain mean was 0.71 and blood mean was 0.21). The mean brain/blood ratios of cocaine and benzoylecgonine concentration in overdose cases were found to be 8.06 for cocaine and 0.67 for benzoylecgonine; in incidental cases, 2.28 for cocaine and 1.67 for benzoylecgonine (Tables 1 and 2). Taking into account that tolerance occurs, and in the absence of any other data about parenchymal distribution or past history of use, it seems clear that isolated blood cocaine levels cannot be used to explain the cause of death, that, except in the case of massive overdose cocaine associated deaths are not doserelated. This is not the case when both brain and blood ratios of cocaine and benzoylecgonine concentrations are considered. It has been recommended that the total concentration of cocaine products can be determined by adding the concentration of cocaine and benzoylecgonine because its presence is due to hydrolysis of the most recent cocaine dose before death. However, since the metabolites can accumulate, and since benzoylecgonine has much lower volume of distribution than cocaine [13] the concentrations in post-mortem blood may be artifactual, and concentrations in other body compartments must be evaluated. It appears that brain tissue is a better sample for cocaine determination than post-mortem blood. In fact comparison of the ratio of cocaine and its major metabolite benzoylecgonine between brain and blood is more useful than any single concentration in the single compartments, in order to make a correct evaluation [14]. This information should also aid interpretation of findings as regarding a history acute or chronic exposure: high brain concentration of cocaine but low or absent metabolite levels indicates a recent exposure, as the presence of benzoylecgonine in the presence of little or no cocaine suggests chronic use or a relatively remote use. We are aware that post-mortem measurements of drug concentration do not necessarily correlate to drug toxicity and cannot explain the cause of death involving cocaine; nevertheless we think that one of the most important criteria for the
interpretation of the cause of death would be an accurate study of distribution of parent drugs and their metabolites in all body compartments (especially brain in comparison to blood), including analysis of hair. This is useful to demonstrate a chronic use or abuse and also when it is not possible to detect cocaine in body fluids or when cocaine levels are very low. For an accurate interpretation of death, any diagnosis reached by means of toxicological findings must be always supported by both histological and autopsy data and circumstances surrounding the case, as recently emphasized by an Editorial on ‘‘Forensic Science in the dock’’, recently published on BMJ [15]. References
[1] C. Klein, Y. Balash, L. Pollak, J. Hiss, M.J. Rabey, Body packer: cocaine intoxication, causing death, masked by concomitant administration of major tranquilizers, Eur. J. Neurol. 7 (2000) 555–558. [2] R.J. Henning, J. Cuevas, D. Ivancsits, A. Sanchez, Cocaine activates calcium/calmodulin kinase II and causes cardiomyocyte hypertrophy, J. Cardiovasc. Pharmacol. 48 (2006) 802–813. [3] S.B. Karch, B.S. Stephens, When is cocaine cause of death? Am. J. Forensic Med. Pathol. 12 (1991) 1–2. [4] A.J. Jenkins, B. Levine, J. Titus, J.E. Smialek, The interpretation of cocaine and benzoylecgonine concentrations in post-mortem cases, Forensic Sci. Int. 101 (1999) 17–25. [5] B.K. Logan, D. Smirnow, R.G. Gullberg, Lack of predictable site-dependent differences and time-dependent changes in postmortem concentration of cocaine, benzoylecgonine, and cocaethylene in humans, J. Anal. Toxicol. 20 (1997) 23–31. [6] S.B. Karch, Interpretation of blood cocaine and metabolite concentrations, J. Emerg. Med. 18 (2000) 635–636. [7] S.B. Karch, Pathology of Drug Abuse, CRC Press, Boca Raton (FL), 2002 . [8] O.H. Drummer, J. Gerostamoulos, Postmortem drug analysis: analytical and toxicological aspects, Ther. Drug. Monit. 24 (2002) 199–209. [9] K.S. Kalasinsky, T.Z. Bosy, G.A. Schmunk, L. Ang, V. Adams, S.B. Gore, J. Smialek, Y. Furukawa, M. Guttman, S.J. Kish, Regional distribution of cocaine in postmortem brain of chronic human cocaine users, J. Forensic Sci. 45 (2000) 1041–1048. [10] B.G. Stephens, J.M. Jentzen, S.B. Karch, D.C. Mash, C.V. Wetli, Criteria for the interpretation of cocaine levels in human biological samples and their relation to the cause of death, Am. J. Forensic Med. Pathol. 25 (2004) 1–10. [11] S.N. Giorgi, J.E. Meeker, A 5 years stability study of common illicit drugs in blood, J. Anal. Toxicol. 19 (1995) 392–398. [12] V.R. Spielher, D. Reed, Brain concentraions of cocaine and benzoylecgonine in fatal cases, J. Forensic Sci. 30 (1985) 1003–1011. [13] J.J. Ambre, T.J. Connelly, T.I. Ruo, A Kinetic model of benzoylecgonine disposition after cocaine administration in humans, J. Anal. Toxicol. 15 (1991) 17–20. [14] loc. cit. [10] [15] O. Drummer, A.R.W. Forrest, B. Goldberger, S.B. Karch, Forensic science in the dock, Editorial BMJ 329 (2004) 636–637.
Cocaine-related deaths: An enigma still under investigation
Elisabetta Bertol a,*, Claudia Trignano b, Maria Grazia Di Milia a, Marianna Di Padua a, Francesco Mari a
a
Forensic Toxicology Division, Department of Anatomy, Histology and Legal Medicine, University of Florence, Italy b Institute of Legal Medicine, University of Sassari, Italy Received 20 December 2006; received in revised form 23 July 2007; accepted 24 July 2007 Available online 30 August 2007
Abstract In recent years there has been an increase interest in cocaine-related death reflecting the rising trend in cocaine use in Europe. Nevertheless is still now very difficult to attribute a death to cocaine. We can affirm that cocaine can be responsible for the cause of death only when there is a reasonably complete understanding of the circumstances or facts surrounding the death. Isolated blood cocaine levels are not enough to assess lethality, should be always considered and evaluated in relation to concentrations of cocaine and benzoylecgonine concentrations in body tissue compartments, especially in brain and blood. We have reanalyzed all of our cocaine-related case from 1990 to 2005, applying the methodology used by Spielher and Reed over 30 years ago. Our aim was to try to validate this model and verify its applicability and effectiveness after 20 years. # 2007 Elsevier Ireland Ltd. All rights reserved.
Keywords: Cocaine; Cause of death; Cocaine-related cases
1. Introduction Except in the case of massive drug exposure (courier or ‘‘body packers’’), where acute toxicity is dose-related and is characterized primarily by its sympathomimetic effects (tachycardia, hypertension and hyperthermia arrhythmias) [1], cocaine-related deaths occur for the major part after prolonged drug use. Long term use of cocaine initiates a series of changes at molecular, cellular and tissue levels [2], many of which favour the occurrence of sudden cardiac death. However, because the cause of death in these cases is not dose-related (except in trivial sense of prolonged usage of large amount), demonstration of the presence of cocaine in fluids or tissues is not sufficient to prove that death was due to cocaine [3]. The criteria for the identification of deaths caused by cocaine intoxication, as for other types of drug deaths, are (1) a review of investigative findings, followed by (2) a complete autopsy, and (3) the identification, confirmation and
* Corresponding author at: Istituto di Medicina Legale, Dipartimento di Anatomia, Istologia e Medicina Legale, Policlinico Careggi, Viale Morgani no. 85, 50134 Firenze, Italy. Tel.: +39 0557947208; fax: +39 0557947208. E-mail address: elisabetta.bertol@unifi.it (E. Bertol). 0379-0738/$ – see front matter # 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.forsciint.2007.07.011
quantification of cocaine and/or its metabolites in samples taken from the cadaver [4]. The literature offers considerable toxicological data about cocaine-related deaths [5–9], and it is clear that correlation of a specific blood or tissue concentration with toxicity is not generally possible. For some authors, establishing the presence of cocaine in the blood, in the absence of other findings, may signify death by cocaine poisoning, but others would undoubtedly insist that isolated cocaine levels cannot be used to explain the cause of death. In fact the presence of low levels of cocaine are proof only of cocaine use, if the appropriate anatomical or histological changes are present, cocaine may be the cause of death even if it is not detectable in the blood. This reality explains why it is impossible to correlate a specific blood concentration to toxicity and also why trying to establish a concept of minimum fatal concentration for cocaine is a futile and inappropriate exercise. The interpretation of toxicological findings in cocaineassociated deaths is complicated by various factors including route of administration, continued absorption after death, different metabolism in chronic or occasional user (the half life of cocaine is considered to be about one-half to one and onehalf hours while in chronic users there is some evidence that it
122
E. Bertol et al. / Forensic Science International 176 (2008) 121–123 361, 346); Nalorfine (455, 414, 440, 324)]. The oven temperature was programmed in the range 60 (2 min)–300 (4 min)8C, at 30 8C/min. The injector was temperature-programmed at 300 8C. Carrier gas: He 20 ml/min flow rate.
may be significantly longer than this. The half-life of benzoylecgonine does not appear to be the same in both acute or chronic users); [10] however in vitro degradation of both parent drug and metabolite may occur over time, especially, when stored at ambient temperature even when the blood is stored in tubes with preservatives. Autopsy must be performed within 24–48 h of death with the body stored at 4 8C for much of the time and blood specimens must be refrigerate until analysis [11], in order to minimize the effects of post-mortem redistribution of cocaine and its major metabolite, benzoylecgonine (the drug is sequestered to some extent in tissue such as the heart muscle and therefore has the potential to be released into the blood during the post-mortem interval). Heart blood should never be used for toxicological evaluation. Cocaine freely and rapidly crosses the blood brain barrier, but benzoylecgonine does not cross at all. It follows that any benzoylecgonine detected in the brain was produced in the brain, and not transported from elsewhere. Supposing that post-mortem blood concentrations of cocaine and its metabolites cannot be used to predict the interval between the last administration and death, given that the brain is the best matrix for cocaine analysis because cocaine concentrations found in post-mortem blood may not be representative of the concentrations existing at the time of death, Spielher and Reed [12] have investigated the interpretative value of the determination of cocaine and benzoylecgonine in blood and brain tissue and their correlation. Since in our Forensic Toxicology Division all suspected cocaine cases (overdoses and incidental deaths) were always investigated for cocaine and its metabolites distribution in biological fluids and tissues, we wanted to apply the Spielher and Reed model to our cocaine-related cases from 1990 to 2005. Our aim was to try to validate this model and verify its applicability and effectiveness after 20 years.
2. Materials and methods
We work with data obtained from analysis of blood and brain on 84 ascertained cases identified as cocaine overdose fatalities (considering toxicological analysis, all context of death circumstances, autopsy and histological findings), and on 33 cases where cocaine was incidental to the cause of death. During the years every sample has been analyzed with the following method.
2.2. Sample preparation
Post-mortem brain tissue and blood samples, removed at autopsy, were stored at À80 8C until analysis. Brain tissue (1 g) and blood (1 ml) were added to distilled water (4 ml), plus the internal standard (1 ml nalorfine at 1 mg/ml concentration), potassium phosphate buffer 0,1 M (pH 6) (2 ml). The sample was mixed with a vortex shaker, centrifuged and filtrated.
2.3. Extraction procedure
To prepare the solid phase extraction column (Bond Elut Certify SPEVARIAN (Harbor City, California, USA), 2 ml of methanol and 2 ml of potassium phosphate buffer were passed through the column without allowing the solvent to dry. The sample was then applied to the column and drawn through. The column was washed with 2 ml of distilled water, 3 ml of hydrochloric acid and 5 ml of methanol and then allowed to dry for 5 min at full vacuum. Finally, 3 ml of elution solvent (methylenechloride: isopropanol [80:20] at 2% ammonium hydroxide) was added to the column and allowed to pass through by gravity. The eluate was collected and evaporated at room temperature.
2.4. Derivatisation
The residue from evaporation of the extract was reconstituted with 50 ml of MSTFA (Sigma–Aldrich Chemie Steinheim, Germany). The mixture was then heated to 75 8C for 15 min in a heating block and 1 ml aliquot was injected into the GC/MS.
2.5. Quantitative analyses
Quantification was performed by construction of five-point calibration curve prepared by spiking drug-free blood and homogenized brain at the following final concentration: 0.05, 0.2, 0.5, 1 and 2 mg/ml. A good linear regression was obtained (y = 0.185x + 1.32, R2 = 0.965, blood; y = 0.611x + 2.75, R2 = 0.972, brain). Accuracy and inter-day precision (calculated as relative standard deviation and bias) were always better than 12%. According to validation results the lower limit of quantification (LLOQ) was determined to be 0.05 mg/ml.
3. Results Results obtained from analysis of cocaine and benzoylecgonine concentrations in blood and brain, and their ratios, on overdose and incidental finding in our cocaine-related case from 1990 to 2005, were resumed in Tables 1 and 2. 4. Discussion and conclusions Spielher and Reed, in their study, found that in 37 autopsied cases of cocaine-related deaths (overdose) the mean cocaine/
2.1. Instrumentation
Extracts were analyzed in a Thermoquest Trace GC/Finningan Polaris Q MS, equipped with a 12 m  0.2 mm i.d. phenylmethylsilicone 5% (5 MS) capillary column with a 0.33 mm film thickness. The instrument was used in the full scan electron ionization mode, scanning m/z in the range 75–500 and in the acquisition SIM mode [Cocaine (182, 82, 303, 272); Benzoylecgonine (82, 240, Table 1 Cocaine/B.E. ratios in blood and brain Fatalities
Coca/B.E. ratio, mean Æ S.D. Blood Brain 10.28 Æ 5.79 0.71 Æ 0.61 14.70 0.87
Forensic Tox Division, Florence, 1990–2005 Spiehler and Reed [12]
Overdose (84 cases) Incidental (33 cases) Overdose (37 cases) Incidental (46 cases)
0.69 Æ 0.53 0.21 Æ 0.15 0.64 0.27
E. Bertol et al. / Forensic Science International 176 (2008) 121–123 Table 2 Brain/blood ratios for cocaine and benzoylecgonine Fatalities Brain/blood ratio, mean Æ S.D. Cocaine Forensic Tox Division, Florence, 1990–2005 Spiehler and Reed [12] Overdose (84 cases) Incidental (33 cases) Overdose (37 cases) Incidental (46 cases) 8.06 Æ 4.45 2.28 Æ 1.23 9.60 2.50
123
Benzoylecgonine 0.67 Æ 0.47 1.67 Æ 0.93 0.36 1.40
benzoylecgonine concentration ratio in the brain is always ten or more times higher than in the plasma, whereas where cocaine was only an incidental finding (46 case instances of murder, accidental death, etc.), the cocaine/benzoylecgonine concentration ratio in the brain was only three or four times higher than in the plasma. Our findings were in agreement with those of the Spielher and Reed studies. In fact we found that in overdose cases the mean ratios of cocaine/benzoylecgonine in the brain were 10.28 and in the blood 0.69, and were clearly different from those found in incidental cases (brain mean was 0.71 and blood mean was 0.21). The mean brain/blood ratios of cocaine and benzoylecgonine concentration in overdose cases were found to be 8.06 for cocaine and 0.67 for benzoylecgonine; in incidental cases, 2.28 for cocaine and 1.67 for benzoylecgonine (Tables 1 and 2). Taking into account that tolerance occurs, and in the absence of any other data about parenchymal distribution or past history of use, it seems clear that isolated blood cocaine levels cannot be used to explain the cause of death, that, except in the case of massive overdose cocaine associated deaths are not doserelated. This is not the case when both brain and blood ratios of cocaine and benzoylecgonine concentrations are considered. It has been recommended that the total concentration of cocaine products can be determined by adding the concentration of cocaine and benzoylecgonine because its presence is due to hydrolysis of the most recent cocaine dose before death. However, since the metabolites can accumulate, and since benzoylecgonine has much lower volume of distribution than cocaine [13] the concentrations in post-mortem blood may be artifactual, and concentrations in other body compartments must be evaluated. It appears that brain tissue is a better sample for cocaine determination than post-mortem blood. In fact comparison of the ratio of cocaine and its major metabolite benzoylecgonine between brain and blood is more useful than any single concentration in the single compartments, in order to make a correct evaluation [14]. This information should also aid interpretation of findings as regarding a history acute or chronic exposure: high brain concentration of cocaine but low or absent metabolite levels indicates a recent exposure, as the presence of benzoylecgonine in the presence of little or no cocaine suggests chronic use or a relatively remote use. We are aware that post-mortem measurements of drug concentration do not necessarily correlate to drug toxicity and cannot explain the cause of death involving cocaine; nevertheless we think that one of the most important criteria for the
interpretation of the cause of death would be an accurate study of distribution of parent drugs and their metabolites in all body compartments (especially brain in comparison to blood), including analysis of hair. This is useful to demonstrate a chronic use or abuse and also when it is not possible to detect cocaine in body fluids or when cocaine levels are very low. For an accurate interpretation of death, any diagnosis reached by means of toxicological findings must be always supported by both histological and autopsy data and circumstances surrounding the case, as recently emphasized by an Editorial on ‘‘Forensic Science in the dock’’, recently published on BMJ [15]. References
[1] C. Klein, Y. Balash, L. Pollak, J. Hiss, M.J. Rabey, Body packer: cocaine intoxication, causing death, masked by concomitant administration of major tranquilizers, Eur. J. Neurol. 7 (2000) 555–558. [2] R.J. Henning, J. Cuevas, D. Ivancsits, A. Sanchez, Cocaine activates calcium/calmodulin kinase II and causes cardiomyocyte hypertrophy, J. Cardiovasc. Pharmacol. 48 (2006) 802–813. [3] S.B. Karch, B.S. Stephens, When is cocaine cause of death? Am. J. Forensic Med. Pathol. 12 (1991) 1–2. [4] A.J. Jenkins, B. Levine, J. Titus, J.E. Smialek, The interpretation of cocaine and benzoylecgonine concentrations in post-mortem cases, Forensic Sci. Int. 101 (1999) 17–25. [5] B.K. Logan, D. Smirnow, R.G. Gullberg, Lack of predictable site-dependent differences and time-dependent changes in postmortem concentration of cocaine, benzoylecgonine, and cocaethylene in humans, J. Anal. Toxicol. 20 (1997) 23–31. [6] S.B. Karch, Interpretation of blood cocaine and metabolite concentrations, J. Emerg. Med. 18 (2000) 635–636. [7] S.B. Karch, Pathology of Drug Abuse, CRC Press, Boca Raton (FL), 2002 . [8] O.H. Drummer, J. Gerostamoulos, Postmortem drug analysis: analytical and toxicological aspects, Ther. Drug. Monit. 24 (2002) 199–209. [9] K.S. Kalasinsky, T.Z. Bosy, G.A. Schmunk, L. Ang, V. Adams, S.B. Gore, J. Smialek, Y. Furukawa, M. Guttman, S.J. Kish, Regional distribution of cocaine in postmortem brain of chronic human cocaine users, J. Forensic Sci. 45 (2000) 1041–1048. [10] B.G. Stephens, J.M. Jentzen, S.B. Karch, D.C. Mash, C.V. Wetli, Criteria for the interpretation of cocaine levels in human biological samples and their relation to the cause of death, Am. J. Forensic Med. Pathol. 25 (2004) 1–10. [11] S.N. Giorgi, J.E. Meeker, A 5 years stability study of common illicit drugs in blood, J. Anal. Toxicol. 19 (1995) 392–398. [12] V.R. Spielher, D. Reed, Brain concentraions of cocaine and benzoylecgonine in fatal cases, J. Forensic Sci. 30 (1985) 1003–1011. [13] J.J. Ambre, T.J. Connelly, T.I. Ruo, A Kinetic model of benzoylecgonine disposition after cocaine administration in humans, J. Anal. Toxicol. 15 (1991) 17–20. [14] loc. cit. [10] [15] O. Drummer, A.R.W. Forrest, B. Goldberger, S.B. Karch, Forensic science in the dock, Editorial BMJ 329 (2004) 636–637.
