The Forensic Implications of Cocaine – Richard Jones
The Forensic Implications of Cocaine
The Forensic Implications of Cocaine – Richard Jones
Introduction Cocaine use in the UK is on the increase, particularly in London and the South East, and is mirroring the situation in the US. Cocaine is often thought of as a ‘safe’ drug, but more and more evidence is becoming available suggesting that this is not the case. This report aims to consider the forensic aspects of cocaine abuse, from the point of view of the Forensic Medical Examiner (FME) in terms of clinical signs and symptoms; the Forensic Psychiatrist in terms of the psychiatric effects of cocaine intoxication and chronic abuse (with a discussion of the phenomenon of ‘excited delirium’) and the forensic pathologist in terms of investigating the death of a suspected cocaine abuser, including findings at the scene of death and at autopsy. A description is also given of the basic pharmacology of cocaine and it’s most important metabolites (including cocaethylene), the analysis of samples taken for forensic investigation and the epidemiology of cocaine abuse.
Cocaine and ‘Crack’ Cocaine Cocaine (benzoylmethylecgonine, C17H21NO4) is an alkaloid prepared from the leaves of the Erythroxylon coca plant, which grows mainly in South Africa, and to a lesser extent in Africa, the Far East and India. For centuries, the large Indian population of Peru have chewed coca leaves, and they have been found in the tombs of their ancestors dating back to 600 AD. Coca leaves were first used in medicine in 1596, but it was not until the mid 1800’s that cocaine was extracted. Freud reported the effects of cocaine in 1884, and it was subsequently utilised in ophthalmology and dentistry as a local anaesthetic. (Cregler et al (1986) pp.1495-6). Cocaine hydrochloride is prepared by dissolving the alkaloid in hydrochloric acid, forming a water soluble salt. It is sold illicitly as a white powder, or as crystals or granules. (See fig 1. illustrating the coca leaves and cocaine hydrochloride). Fig 1. Coca Leaves and Cocaine Hydrochloride powder
Street names include ‘coke’, ‘charlie’, ‘nose-candy’, ‘snow’ and ‘wash’. This form of cocaine can be ‘freebased’, prior to smoking, in which it is dissolved in ether or ammonia. The ‘freebase’ remains after the volatile substance has evaporated. Although this form of cocaine was popular in the late 1970s, a further refinement of this process became more prominent in the US during the 1980s, in which ‘crack’ cocaine was produced. Crack cocaine is produced when cocaine hydrochloride is mixed with sodium bicarbonate (baking soda) and water, and then heated. On cooling, ‘rocks’ are precipitated, and these are smoked in crack pipes, or are heated on foil with the vapour inhaled. Crack is an extremely ‘pure’ form of an already ‘pure’ substance (in comparison with other drugs of abuse such as amphetamines). Fig 2. Illustrates ‘rocks’ of crack cocaine.
The Forensic Implications of Cocaine – Richard Jones
Fig. 2. ‘Rocks’ of Crack Cocaine
Cocaine can be administered as a drug of abuse in the following ways,
• • •
Cocaine hydrochloride – snorting (intranasal), smoking, intravenous (including being mixed with heroin (‘speedball’ or ‘snowball’)), ingestion, application to genitalia Crack cocaine – inhalation of vapour from heated foil or pipe Coca leaves – chewed/ ingested
In the UK, cocaine is classified as a Class A controlled drug, by virtue of Schedule 2 of the Misuse of Drugs Act 1971 (as amended by the Misuse of Drugs Regulations 1985). It is a criminal offence to ‘unlawfully possess’ (with or without intent to supply), to import or export the drug, or produce it, and the police have extensive ‘stop and search’ powers to enforce these offences. Cocaine addicts are required to be notified by doctors to the Chief Medical Officer under Regulation 3 of the Misuse of Drugs (Notification of and supply to Addicts) Regulations 1973, and Regulation 4 prevents doctors from prescribing cocaine unless they are licensed to do so by the Home Secretary. However, this does not apply to those treating organic disease or injury.
Epidemiology Epidemiological data of drug misuse in the UK is not freely available in the same way that it is in the US because there is no ‘National Drugs Survey’ or ‘National Household Drugs Survey’. However, data have been collated by the Health Education Authority (1995), and as part of the 2 yearly British Crime Survey (most recently in 1998). The Four Cities Study (1992), and the Youth Lifestyle Survey (1993) also provided useful data on drug misuse in the populations covered by the study. (BMA 1997 pp,13-27, Institute for the Study of Drug Dependence, British Crime Survey 1998). The following points of note can be extracted from the data, • • • • • •
32% of the adult population is thought to have used a drug at some point in their life (11% in the last year, 6% in the last month) 49% of under 30s report having used a drug (16% within the last month) the highest adult prevalence is in the 16-19 year age group – 31% using drugs on a regular basis drug use peaks at the end of the teens male users outstrip female users by 2:1 unskilled workers abuse drugs more than other social classes, and chose more dangerous routes of administration
The Forensic Implications of Cocaine – Richard Jones •
the highest prevalence is found among the unemployed – 40% report drug use within the last year ethnic differences in drug abuse were negligible overall, but the type of drug abused varied (e.g. whites were found to abuse amphetamines and LSD more than AfroCaribbeans). Drug use amongst Indians, Pakistanis and Bangladeshis was appreciably lower 48% of male prisoners use drugs whilst in prison
• • •
In terms of cocaine and crack use, the data is often grouped with heroin use, and is not always easy to separate out, • • • • • • • •
1% of 20-50 year olds had used these drugs 9% of 16-29 year olds had taken these drugs, with cocaine representing a large proportion of this cocaine use is on the increase among young people, particularly in the London area (due to increased availability and reduced cost?) cocaine use has increased to 3% of 16-44 year olds – London and the South East have borne the brunt of this increase a recent ‘Time Out’ readers poll found that 3% used cocaine regularly, with 45% having taken it at least once (compared to 2% and 6% respectively for crack) heavy cocaine users spent £100 per day to support their habit regular crack cocaine users could spend over £1000 over a weekend on 10g of the drug cocaine related deaths are increasing – 38 in 1997 compared to 18 in 1996
American data indicate that 23.7 million people used cocaine between 1990-1, nearly 4 million of which were using crack. (Cone 1993). Mortality from cocaine abuse has also risen, and cocaine accounts for the most frequent substance related deaths. (Karch 1991(a) p.126).
Pharmacology Pharmacokinetics Cocaine has a half life of 40-50 minutes, and it’s effects on the body are felt rapidly, peaking after 15-20 minutes when ‘snorted’, and wearing off by 1.5 hours. When injected or ‘freebased’, or when crack is smoked, the effects are almost instantaneous, and last for only 15 minutes or so. Cocaine is metabolised to nearly a dozen pharmacologically inactive metabolites, the most important being benzoylecgonine and ecgonine methyl ester, primarily in the liver by spontaneous hydrolysis. (Casale et al 1994). Plasma cholinesterase also hydrolyses cocaine to ecgonine, and approximately 20% of the drug is excreted untouched into the urine. Both cocaine and its metabolites may be detected in urine up to 15 days after last administration by a chronic user. Cocaethylene is the ethylbenzoylecgonine form of cocaine produced in the presence of ethanol, resulting from transesterification by hepatic enzymes. (da Matta Chasin et al 2000 p.2). It is pharmacologically active, and it is formed at significantly lower concentrations than either of its parent substances. See fig 3. below for examples of cocaine metabolites.
The Forensic Implications of Cocaine – Richard Jones
Fig 3. Chemical structures of cocaine, norcocaine and the important metabolites.
Mechanisms of Action Cocaine is a central nervous system stimulant, which gives rise to feelings of euphoria, excitement, increased motor activity and a feeling of being energised. Its principal mode of action is the blockade of the transporter protein that is responsible for the reuptake of monoamines (i.e. noradrenaline, serotonin and most importantly dopamine) into presynaptic terminals of neurons releasing these neurotransmitters. The result is that increased concentrations of these monoamines are found in the synaptic space, and their effects are potentiated. Blockage of the dopamine-reuptake transporter protein gives rise to the characteristic ‘high’ of cocaine. Knockout mice that do not have the gene encoding for this transporter protein are immune to the effects of cocaine, and studies have attempted to identify the exact dopamine receptor subtype on the post-synaptic neuron that is responsible for modulating the effects of cocaine. It appears that the D2 subtype modulates cravings associated with cocaine dependence and drug seeking behaviour, whilst the D1 subtype may modulate feelings of satiety, opening up possibilities for therapeutic targeting of these receptors to treat cocaine dependence and abuse. (Leshner 1996 pp.128-9). Dopamine hyperactivity as a result of cocaine administration is particularly important in the nigrostriatal dopaminergic system, which incorporates the limbic system of the brain – the ‘pleasure centre’. The activation of the limbic system by the drug gives rise to the intense euphoria, but in the chronic user, monoamine neurotransmitters are depleted, triggering a reactive lowering of mood or depression (serotonin depletion?), as well as disturbed sleep and eating cycles. Body temperature control is adversely affected, and depletion of dopamine has been linked to the onset of schizophrenia in susceptible individuals. Fig 4 below illustrates the mechanism of action of cocaine.
The Forensic Implications of Cocaine – Richard Jones
Fig 4. Mechanism of action of Cocaine (Leisner 1996 pp.128-9)
In high doses, cocaine can cause tremors and convulsions via its effects on the cortex and brainstem, and can lead to respiratory and vasomotor depression. O’Dell et al (2000 p.677) speculate that cocaine activation of serotonin (2) receptors may be responsible for mediating convulsions. Chronic users can experience hallucinations, delusions and paranoia. Peripherally, cocaine potentiates noradrenaline action, and produces the typical ‘fight or flight’ sympathetic response of tachycardia, hypertension, pupillary dilatation and peripheral vasoconstriction. Table 1 below lists the effects of cocaine.
The Forensic Implications of Cocaine – Richard Jones
Table 1. Physical and Psychological Effects of Cocaine (Sources: Stark et al 1996, Stark 1999, Wetli (1985)) Dose Initial Low Doses
Physical Effects
Psychological Effects
Tachycardia, tachypnoea, hypertension, Dilated pupils (& flattened lenses), sweating, reduced appetite, reduced need for sleep, reduced lung function, dry mouth, impaired motor control & performance of delicate skills and driving
Euphoria, sense of well being, impaired reaction time and attention span, impaired learning of new skills
Increased doses
Seizures, cardiac arrhythmias, myocardial infarction, stroke, respiratory arrest
Chronic Use
Erosions, necrosis and perforation of nasal septum, anosmia, rhinorrhoea and nasal eczema (snorting), chest pains, muscle spasms, sexual impotence, weight loss, malnutrition, vascular disease
Anxiety, irritability, insomnia, depression, paranoia, aggressiveness, impulsivity, delusions, agitated/ excited delirium, reduced psychomotor function Dependence, disturbed eating and sleeping patterns
Therapeutic Uses of Cocaine Cocaine is used as a surface local anaesthetic (it blocks Na+-K+ activated ATPase across adrenergic neuron cell membranes), particularly in Ear, Nose and Throat (ENT) surgery. It is also sometimes used in palliative care of terminally ill patients.
Dependence and Tolerance There is tolerance to the psychological effects of cocaine, but not generally to the cardiac effects. However, acute tolerance appears to occur after administration of the drug. This has been noted when studying the effects of cocaethylene, which is formed at a slow rate, and appears in the user’s blood at a time when the effects of cocaine are declining. Cocaethylene is active in the brain, and has a similar effect to cocaine, but the subjective perception of the cocaine ‘high’, and its heart effects are not increased – instead they decline in intensity. Niesink et al (1999 p.49) describes the ‘super sensitivity’ phenomenon that follows chronic cocaine use, and represents a form of chronic tolerance. Chronic use depletes the amount of monoamine neurotransmitters in the pre-synaptic neuron, and thus the amount available in the synaptic cleft. This is compensated for by an increase in post-synaptic receptors. Cocaine causes both physical and psychological dependence, the severity of which depends on the route of drug administration. It is more severe when the drug has been injected or smoked. Withdrawal leads to strong craving and drug seeking behaviour, followed by a withdrawal syndrome. The cocaine ‘crash’ is characterised by • • • • • • • • •
irritability insomnia depression anxiety muscle pains tremor hunger fatigue hypersomnic episodes
The Forensic Implications of Cocaine – Richard Jones Sufferers are at an increased risk of harming themselves or committing suicide, and frequently find themselves in police custody. Such individuals can be settled with haloperidol and diazepam, whilst their vital signs need close monitoring in a hospital setting where potential complications may be anticipated.
Cocaethylene When alcohol and cocaine are ingested together, the liver produces the active metabolite cocaethylene. It is produced as a result of the transesterification of cocaine by the same nonspecific carboxylesterases that normally convert cocaine to benzoylecgonine, for example, in the absence of ethanol. Cocaethylene is a non-polar structure, and can cross the blood brain barrier, where it blocks the dopamine-reuptake transporter protein in the same way that cocaine does. The clinical importance of this metabolite has not been fully determined, but it has a longer halflife than cocaine (2.5 hours), and it is possible that it may prolong the cocaine ‘high’. (Cone et al 1993). However, Perez-Reyes et al (1992 pp. 561-2 and 1994 pp.541-550) have found that cocaethylene appearance in the blood of a cocaine/ ethanol user does nothing to alter subjective cocaine ‘highs’ or increased heart rate etc. Indeed, it appears that the interaction between cocaine and ethanol is ‘order-of-administration’ dependant. Ethanol only appears to enhance the effects of cocaine if it is ingested prior to cocaine. The issue of cocaine/ ethanol interaction is controversial. Karch et al (1999 pp.19-23) suggest that cocaine toxicity is not enhanced by ethanol-cocaine interactions, when low concentrations of ethanol are ingested. They concede, however, that further research is required to determine the interactions of higher concentrations of ethanol with cocaine. The US Drug Abuse Warning System (DAWN) has identified cocaine/ethanol abuse as a major cause of emergency medical admissions, and considers the concurrent use of these drugs to be the cause of increases in cocaine related morbidity and mortality, as well as giving rise to an increased risk of dual dependency and worsening of the ‘crash’ associated with chronic use. (Lee Hearn et al 1991 p.698 and da Matta Chasin et al 2000 p.2). Epidemiological evidence of the combined abuse of cocaine and ethanol in the US estimates that 5 million people had used this combination within 1 month of the National Household Drug Survey (1985), and that 12 million had done so within the preceding year. Despite a general decline in the prevalence of cocaine use reported by the 1990 Survey, the proportion combining both substances had increased. (Perez-Reyes and Jeffcoat 1992 p.553). Data are unavailable for combined use in the UK, but it is conceivable that the increase in cocaine use in the UK will be mirrored with an increase in the combined abuse of cocaine and ethanol.
Analysis of Clinical and Forensic Specimens for Cocaine and Metabolites The identification of cocaine or its metabolites in clinical specimens assists patient management in clinical forensic medicine, and assists the pathologist in ascertaining cause of death. Urine is convenient and easy to collect, and represents a longer chronological picture of drug use than does the analysis of blood or saliva. The half-life of cocaine is short, and cocaine and its metabolites remain in the urine for up to 14 days in a chronic user (Karch 1991(a) p.126). False negatives may result from bleach and salt added to specimens surreptitiously, and those individuals with cholinesterase deficiencies continue to have detectable levels for a long time. Recent advances have been made in the analysis of hair for toxicological purposes, and Cone et al (1993 pp.55-68) describe the results of analyses of head and arm hair for cocaine and it’s metabolites. Concerns have been raised, however, about the issue of external contamination of hair shafts by smoke and sweat containing cocaine, and the implications for interpretation of positive analyses. Various pre-wash techniques have been described (Kintz et al 1995 pp.3-11 and Blank et al 1993 pp.145-156), but the matter is far from being resolved.
The Forensic Implications of Cocaine – Richard Jones
Analysis of samples Specimens need to be collected and preserved in sodium fluoride (or another pseudocholinesterase inhibitor), and refrigerated. Storage in a buffer at pH 5 can also prevent cocaine metabolism prior to analysis. (Karch 1991(a)). Cocaine levels need to be interpreted with extreme care, because it is rapidly metabolised in blood, and continues to be broken down in post-mortem blood if incorrectly stored for analysis. (Wetli 1987p.2). Commercially available test kits are available (e.g. EMIT d.a.u. – an enzyme based immunoassay kit) for screening urine for cocaine metabolites, and positive samples are confirmed using the ‘gold standard’ analytical techniques – gas chromatography/ mass spectrometry (GC/MS). (Cone et al 1990). GC/MS has a lower limit of detectability for cocaine in the blood of <0.5 mcg/L (or 0.5 mg/ml), whereas the therapeutic blood cocaine level is in the region of 3 mcg/L (or 3 mg/ml). (Corburt et al 1993 pp.136-149). Typical blood cocaine levels are found in Table 2. below. Blood levels do not correlate well with psychological and physiological effects, unlike blood alcohol levels, as the measurement could represent a rising level associated with euphoria, or a falling level associated with dysphoria. A chronic user will also have built up tolerance to the effects of cocaine, and so a high blood concentration may not be interpreted as having any specific effect on his/her mental state at the time the sample was taken. Benzoylecgonine is not freely permeable across the blood brain barrier, and its presence at high levels in the brain may indicate cocaine metabolism in the brain, suggesting that the individual is a chronic abuser (Karch 2000 p.431). Table 2. Typical Blood Levels (Sources: adapted from Karch 1991(a) p.127 and Karch 1991 (b) p.1) Description of Administration
Blood Cocaine Levels (mg/ml)
Therapeutic dose Typical intranasal snort (of 100mg) Excited Delirium Fatal / seizure or respiratory depression inducing dose
3 1*10-4 6 600
An interesting development in the analysis of specimens for the presence of cocaine is the report by Nolte et al (1992 pp.1179-1185) of the use of the larvae of the blue bottle fly, Calliphora vicina as a ‘toxicological specimen’, after being found on a decomposed body. Cocaine was found in the larvae, and it is hoped that in the future, the pupal cases will also be capable of being utilised in the same way that hair is currently being examined.
Psychiatric Implications of Cocaine Use Substance Induced Psychosis The abuse of hallucinogenic drugs (e.g. LSD) and stimulants (including cocaine) can give rise to psychological effects listed in Table 1 above. Although the threshold at which an individual might suffer psychotic effects differs, the prolonged use of large quantities may result in a paranoid psychosis, which closely resembles paranoid schizophrenia. The individual may have the following features, • • •
persecutory delusions auditory and visual hallucinations aggressive behaviour
This condition subsides within 1 or 2 weeks of the last administration of the drug, but may last for months.
The Forensic Implications of Cocaine – Richard Jones
A detailed history of any drug use will assist in the differentiation between substance induced psychosis and an underlying psychotic disorder that has been precipitated by use of the drug, which is more likely to have been associated with prodromal symptoms and a decline in personal functioning predating the use of the drug. The period of psychosis may be shortened by ‘urine acidification’ procedures, which hasten drug elimination. (Collier et al 1999p.354, Gelder et al 1994 p.288, Bloye et al 1999 p.56 and Gunn et al 1995).
Delirium and Excited Delirium Delirium is an acute organic mental disorder characterised by an impairment of consciousness, disturbed attention, perception and thinking. Individuals are disorientated and may suffer from visual hallucinations or illusions. Cocaine intoxication has been associated with ‘excited delirium’, which is a syndrome uniquely associated with chronic stimulant abuse, and is a medical emergency. It has the features listed below, and has been described as a ‘state of mental and physiological arousal, agitation, hyperpyrexia with euphoria and hostility’. (Farnham et al 1997 pp.1107-8). Karch (2000 p.431) describes the syndrome as having 4 sequential stages – hyperthermia, agitated delirium, respiratory arrest and death over a time course of approximately 4-6 hours. The following features may be present during the early stages of the disorder, • • • • • • • • • •
fear panic shouting / bizarre behaviour physical violence hyperactivity thrashing about (especially after restraints have been applied) unexplained strength / endurance hyperthermia mydriasis extreme sweating
Deaths from excited delirium cluster in the late summer months, and are more common amongst black males who are more likely to be cocaine injectors, and are younger than those who die of cocaine overdoses. (Karch 2000 p.431). Blood cocaine concentrations are generally in the range of 6 mg/ml, which is twice the therapeutic dose, but are still well below those levels found in fatal cocaine intoxications. The mechanism behind the cause of death in these individuals is not well understood, but could involve autonomic reflexes, arrhythmias or stress during restraint. Exhaustion and postural asphyxia are probably not causal mechanisms because of the lack of overt asphyxial changes seen at autopsy, such as petechial haemorrhages etc. High levels of circulating catecholamines could cause ventricular tacchyarrhythmias, coupled with cocaine induced myocardial hypertrophy in chronic users, and the effects of stress on levels of hydration and the onset of lactic acidosis could all be contributory factors. Treatment in the emergency setting may include the use of neuroleptics for sedation. However, it should be noted that ‘neuroleptic malignant syndrome’ patients may present in a similar manner, and the use of these drugs would clearly worsen their symptoms. Some commentators believe that neuroleptic malignant syndrome is actually a variant of excited delirium (Karch 2000 p.431). The management of excited delirium consists of careful restraint, seclusion and medication, although the use of electro-convulsive therapy (ECT) has also been found to be safe and effective. (Farnham et al 1997 pp.1107-8). An individual acting in a violent and erratic or bizarre manner usually attracts the attention of the police, and a struggle often ensues. After being restrained (often forcibly), the individual may
The Forensic Implications of Cocaine – Richard Jones collapse and die, bringing the police actions into question. Excited delirium and it’s relationship with deaths in custody is thus an increasingly important area of research.
Forensic Pathology of Cocaine Abuse The Scene of Death An examination of the scene of death is useful in suspected cocaine related deaths, so that autopsy findings can be interpreted in context. For example, wet towels at the scene may indicate that the deceased was suffering from terminal hyperthermia, or a barricaded room may support a hypothesis that the deceased was suffering from a psychotic episode in the context of excited delirium etc.
Examination of the Body External Findings Table 3. below illustrates some external findings that may give rise to the suspicion that the deceased was abusing cocaine or crack. Relatives or friends may remove physical evidence of drug use from the vicinity of a body, and in the absence of such paraphernalia, physical signs on the body are important circumstantial evidence. Table 3. External findings giving rise to a suspicion of cocaine abuse (Sources: Wetli 1987 p.1, Karch 1991(a)) Signs suggestive of intravenous use
Signs suggestive of crack use Signs suggestive of intranasal use
Fresh needle tracks, Fresh injection sites (ecchymotic (bruised) areas with a clear central zone around the needle puncture), Shallow cutaneous ulcers with a clean base and pearly margins (toxic effect of cocaine on capillaries), or round/oval scars ‘Crack callus’ (on the ulnar aspect of the thumb) from repeated activation of a flint-lighter Perforation of the nasal septum or collapse (‘saddle nose’ deformity), Enamel erosions of the front teeth (from wiping the cocaine residue across the teeth) Positive nasal swab
Internal Findings General Findings • • • •
visceral congestion pulmonary oedema serosal petechiae signs of terminal convulsions (bite marks on the tongue, cheeks and lower lip)
Cardiovascular System Although the following pathological changes can be diagnostic of cocaine abuse or intoxication, their presence is inconsistent. • •
• •
Endocarditis Eosinophilic myocarditis Previous myocardial infarction (Fig. 5) Contraction band necrosis (Fig. 6) suggesting coronary artery spasm (The aetiology of which has been attributed to myocardial injury caused by increased levels of
The Forensic Implications of Cocaine â&#x20AC;&#x201C; Richard Jones catecholamines, or to a decreased perfusion through the coronary arteries resulting from brief vasospastic episodes of occlusion followed by vasodilatation and reperfusion. (Zugibe et al 1998 p.142). Myocyte injury and necrosis may alternatively be due to cocaineâ&#x20AC;&#x2122;s effects on calcium influx into blood vessels. The severity of contraction band necrosis correlates well with post mortem blood cocaine levels. Cellular infiltration indicates a sub-acute process, and the presence of myocardial fibrosis as well gives an indication of a history of abuse). Fig. 5. Previous Myocardial Infarction
Fig. 6. Contraction Band Necrosis.
The Forensic Implications of Cocaine – Richard Jones
Acute Cardiovascular Pathology Cocaine is directly toxic to cardiac myocytes, and this cardiotoxic effect does not depend on the route of administration, and may not necessarily have to occur at large doses. Neither does it appear that pre-existing cardiovascular pathology is a pre-requisite for cocaine toxicity, although there is some suggestion that a genetic factor may be involved, giving rise to an increased susceptibility to the cardiotoxic effect of cocaine in some individuals. (Isner et al 1986 p.1438). The increased levels of circulating catecholamines associated with cocaine use also appear to damage the heart and great vessels. (Karch 2000 p.430).
Acute Myocardial Infarction The mechanism of cocaine related myocardial infarction is likely to be multifactorial in nature, and could be related to focal vasoconstriction of coronary arteries, or spasm of these arteries. Cocaine acts both directly and indirectly on vascular smooth muscle, via -adrenergic stimulation (noradrenaline) and an independent, dose-related effect. Cocaine also increases coronary vascular resistance at a time when it is increasing heart rate and myocardial oxygen demand. (Isner et al 1989 pp.1604-1606). Coronary artery spasm may not be severe enough to induce ischaemia in fit individuals, but in the context of pre-existing coronary artery disease further reductions in flow are catastrophic. Where there is thrombotic occlusion of coronary arteries, there appears to be no association with atherosclerotic plaque rupture or haemorrhage, as is the case with non-cocaine-related coronary artery thrombosis. (Zugibe et al 1998 p.140). It has also been noted that cocaine depletes protein C and Antithrombin III, giving rise to a procoagulant effect, and increasing the risk of thrombus formation in vasoconstricted coronary arteries. However, other studies have disputed this increased tendency for thrombosis. (Karch 2000 p.430). Anyone with pre-existing cardiac disease, such as coronary artery atherosclerosis will be at an increased risk of developing acute ischaemia because of the predictable effects of cocaine on myocardial oxygen demand etc. (Cregler et al 1986 p.1496). A similar vasoconstriction mechanism has been hypothesised as being responsible for other cocaine related cardiovascular pathology, including,
•
• • • •
• •
Cocaine related haemorrhagic stroke (see Figs. 7 & 8 below). The mechanism of cocaine-related cerebrovascular accidents probably being related to adrenergic stimulation, cerebral vasoconstriction and a sudden surge in blood pressure. (Cregler et al 1986 p.1497 and Levine et al 1990 pp.702-3). Ischaemic stroke and infarction at all levels of the central neuraxis (including spinal cord and retina). This may be due to vasoconstriction, emboli secondary to cardiac arrhythmias or reperfusion injury following momentary ischaemia. Intracranial haemorrhage due to ruptured berry aneurysm or arteriovenous malformation Rupture of aortic aneurysm Rhabdomyolysis Pulmonary haemorrhage, and Peripartum foetal distress and abruption placentae (placental vasoconstriction following cocaine administration, leading to decreased blood flow to the foetus, and the onset of labour)
The Forensic Implications of Cocaine – Richard Jones
Fig. 7. Cerebral haemorrhage.
Fig.8. Cerebral infarction
Cardiac Arrhythmias Cocaine is a Class II antiarrhythmic agent, and exerts its actions by blocking sodium channels. In large doses it is arrhythmogenic, possibly due to it’s effects on catecholamines rather than any direct effect, (Cregler et al 1986 p.1497) or due to secondary arrhythmias following cardiac ischaemia due to prolonged coronary artery vasoconstriction. A cocaine-induced rise in intracellular calcium may also be responsible (Zugibe et al 1998 p.144) and a possible source of the re-entry arrhythmias may be the patchy fibrosis caused by chronic cocaine abuse (Karch 2000 p.431). Cocaine abuse has been linked to the following arrhythmias, • • • • • •
Sinus tachycardia Ventricular premature contractions Ventricular tachycardia and fibrillation Asystole Post infarction arrhythmias Arrhythmias due to a hyperpyrexic state
The Forensic Implications of Cocaine – Richard Jones
Rupture of the Ascending Aorta Cregler et al (1986 p.1497) have reported an acute aortic rupture in a cocaine ‘freebaser’, and hypothesised that the underlying mechanism was a massive increase in systolic blood pressure following an overdose of the drug, in conjunction with the deceased individual’s pre-existing chronic systemic hypertension.
Chronic Cocaine Abuse Related Vascular Pathology The following pathology has been associated with chronic cocaine abuse,
•
• •
Myocardial hypertrophy – long term and excessive catecholamine stimulation causing the heart to work harder, coupled with increased systemic vascular resistance (afterload) caused by high levels of circulating noradrenaline. Cocaine also increases plasma atrial natriuretic peptide, indicative of circulatory overload and pump failure, and a genetic component is also suspected. (Karch 2000 p.430). An enlarged heart, sometimes with patchy fibrosis (see Fig. 9) may be the only abnormality found at the autopsy of a cocaine abuser, and it should be noted that an enlarged left ventricle is an established risk factor in sudden death even in the absence of cocaine use. Cocaine-induced cardiomyopathy (resembling viral myocarditis) – this condition is suspected, and has been reported by several sources (Wetli 1987 p.2 and Zugibe et al 1998 p.140) The promotion of coronary artery disease (atherosclerotic and coronary occlusive disease) due to coronary artery sclerosis/ intimal hyperplasia (of smooth muscle) with or without collagen or elastin. Fig. 10 illustrates coronary artery sclerosis). Possible aetiologies include prolonged vasoconstriction, or stimulation of smooth muscle growth factor, endothelial disruption or injury; the action of nor-adrenaline or platelet derived growth factor (PDGF). (Zugibe et al 1998 p.142-4)
A summary of the cardiotoxic effects of cocaine is shown in Fig. 11 below.
Fig. 9. Patchy myocardial fibrosis.
The Forensic Implications of Cocaine – Richard Jones
Fig. 10. Coronary artery sclerosis.
Fig. 11 Cardiotoxic Effects of Cocaine – Summary (Source: Zugibe et al 1998 p.143)
The Forensic Implications of Cocaine – Richard Jones
Respiratory System Non-specific findings at autopsy include pulmonary oedema and congestion, possible due to excess catecholamine release. Specifically, cocaine use has been associated with,
• • •
granulomas in the lungs, and this may represent either impurities in the drug, or more likely polydrug abuse spontaneous pneumothorax, and spontaneous pneumopericardium (both in freebasing cocaine)
Forrester et al (1990 pp.462-467) report that crack abuse has been associated with,
• • •
• •
•
Haemoptysis (with haemosiderin-laden macrophages in the sputum and alveoli) Pulmonary hypertension (hypertrophy and hyperplasia of medium sized pulmonary arteries) Diffuse alveolar haemorrhages Intra-alveolar inflammatory infiltrates and prominent eosinophilia (with IgE deposition seen in lymphocytes, and alveolar macrophages) Bronchiolitis obliterans Thermal injury to the airway
Gastrointestinal Tract The pathological findings in the gastrointestinal tract of a cocaine abuser are similar to those found in experimental animals treated with high levels of catecholamines, i.e. • •
• •
Ulceration and perforation Ischaemic colitis Severe bowel ischaemia and gangrene (vasoconstriction of mesenteric vasculature) Peptic ulcer perforation (due to a disruption of the internal elastic lamina of the small vessels supplying the ulcerated areas).
The ischaemia is reported to be segmental in distribution (Garfia et al 1990 p.740), with there being no mesenteric vessel thrombus involved. Instead, an increase in intestinal vascular resistance is suspected, due to cocaine’s action on -adrenergic receptors (via noradrenaline). Vasoconstriction leads to a reduction and blood flow, and thus ischaemia.
Urinary System Cocaine use is known to have caused, • • • •
Renal infarction Renal thrombosis Haemolytic uraemic syndrome Rhabdomyolysis with myoglobinuric renal failure
Mechanisms of rhabdomyolysis include a pressure-related injury, vasospasm and myocyte necrosis, hypovolaemia, renal artery vasoconstriction and myoglobinuria. A histological picture similar to acute tubular necrosis has also been reported (vacuolation, fragmentation and desquamation of proximal tubular epithelial cells, with pigmented casts in some distal tubules), and cocaine use may be a risk factor for the development of glomerulosclerosis. (Karch 2000 pp.434-435).
The Forensic Implications of Cocaine – Richard Jones
Central Nervous System (Non-vascular) Due to cocaine’s ability to produce hyperpyrexia, combined with it’s effects on neurotransmitters, the drug may contribute to seizure formation as well as hyperthermia. Seizures may be ‘primary’, due to cocaine lowering the seizure threshold, or ‘secondary’ to cardiac effects such as ventricular tachycardia and fibrillation. (Cregler et al 1986 p.1497).
Excited Delirium • • • • • • • •
Elevated core temperature Abrasions and contusions from struggling against restraints, and fighting with police etc Pulmonary congestion and oedema Cerebral oedema Non-lethal self-inflicted injuries (need to exclude a carotid ‘sleeper hold’) Contraction band necrosis (chronic cocaine use) Slightly enlarged heart Patchy myocardial fibrosis
There is often no anatomically obvious cause of death (Farnham et al 1997 pp.1107-8), but it is necessary to exclude myofibrillar degeneration, as this is a morphological hallmark of stress cardiomyopathy associated with sudden death (Wetli 1985 pp.873-80) A neurochemical explanation for excited delirium has been put forward by several researchers (reported by Karch 2000 p.432), and involves differences in the distribution of dopamine D1 and D2 receptors and a failure of those who die of excited delirium to compensate for chronically high levels of dopamine in the brain by increasing the amount of cocaine recognition sites. Chronic cocaine users will usually have a striking increase of striatal D1 receptors, with no change in D2 receptors. In those with excited delirium, hypothalamic D2 receptors are depleted, and these receptors are known to regulate temperature control. Excessive 2 opiate receptors in the amygdala, nucleus acumbens (and other parts of the limbic system) have also been reported in psychotic cocaine users, and the amygdala is thought to be involved in the integration of emotional responses and autonomic functions. Loss of control of emotional interaction is a classic feature of excited delirium. (Karch 2000 p.432). As neurochemical tests increase in sophistication and accuracy, the differences between non-psychotic chronic abusers and those with excited delirium will be elucidated more effectively. These deaths commonly occur at the time of or shortly after being taken into police custody, and so care must be taken to look for signs of suffocation or asphyxia related to choke holds etc, and whether any police-inflicted injuries were lethal. However, it is important to note that those with excited delirium die whether or not they are restrained, and ascribing the cause of death to ‘positional asphyxia’ (a type of mechanical asphyxia seen in those whose cough reflexes are suppressed by intoxication, or where postural splinting (especially in obese people) prevents chest expansion and complete respiration) is not accurate. (Karch 2000 p.433).
Cocaine Abuse and Cause of Death Karch et al (1991(b) p.1) highlight the implications of ascribing cause of death to cocaine abuse or toxicity, particularly the difficulties interpreting blood cocaine levels and non-specific pathological findings. In the US, cocaine related deaths are considered to be ‘accidental’, and insurers are objecting to this because it means that they are liable to pay out despite their policies excluding payment where death is due to the self-administration of drugs. Persons with plasma pseudocholinesterase deficiency are at risk of sudden death when abusing cocaine, due to their inability to effectively metabolise the drug. In determining whether cocaine abuse is causal, the pathologist should consider all strands of evidence, from the scene of death, the presence of cocaine (at whatever level) in the blood or tissues etc in conjunction with autopsy and histopathological findings. Taken as a whole, this pattern of findings may be enough to ascribe causality. A strong history of cocaine abuse together
The Forensic Implications of Cocaine – Richard Jones with typical myocardial pathology is sufficient evidence in Karch’s view (1991(b) p.2), that cocaine induced sudden death can be ascribed even where toxicology is negative. Sudden death in young people should begin with a consideration of the possible role of cocaine. Fig. 12 below illustrates an algorithm for determining whether cocaine is the cause of sudden death or not. Fig. 12. Algorithm for Cocaine-related Sudden Death (Karch 1991(b) p.1)
Toxicology Results +VE (with only trace or therapeutic levels of other agents)
-VE
+VE history of cocaine use
-VE history of cocaine use
Autopsy
No pathological findings identified
Diagnosis—cocaine or catechol toxicity (rule out phaeochromocytoma)
Diagnosis is microfocal fibrosis (not otherwise
Diagnosis is not cocaine
Summary This report has outlined the forensic aspects of cocaine abuse, which is on the increase in the UK, particularly in London and the South East. Cocaine has wide ranging effects on the body, and cocaine intoxication as well as chronic cocaine use can give rise to serious and life threatening pathologies.
The Forensic Implications of Cocaine â&#x20AC;&#x201C; Richard Jones
Cocaine related sudden death represents a particular challenge to the forensic pathologist in terms of interpretation, because often a range of evidence has to be taken into account before a cause of death can be ascribed to cocaine with the required degree of certainty. This is of particular importance when the death has occurred in police custody â&#x20AC;&#x201C; a highly politically charged situation. Enormous advances have been made over the last decade in the understanding of the pathology associated with cocaine abuse, and as the prevalence of cocaine use spreads, it is likely that cocaine is going to exert itâ&#x20AC;&#x2122;s influence on substance-related deaths in the UK, and thus become an issue of increasing importance to professionals working in forensic science and medicine.
The Forensic Implications of Cocaine – Richard Jones
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