Cardiovascular disorders associated with cocaine use: myths and truths

Chronic Cocaine Use and Parkinson's Disease: An Interpretative Model

Over the years, the growing "epidemic" spread of cocaine use represents a crucial public health and social problem worldwide. According to the 2023 World Drug Report, 0.4% of the world's population aged 15 to 64 report using cocaine; this number corresponds to approximately 24.6 million cocaine users worldwide and approximately 1 million subjects with cocaine use disorder (CUD). While we specifically know the short-term side effects induced by cocaine, unfortunately, we currently do not have exhaustive information about the medium/long-term side effects of the substance on the body. The scientific literature progressively highlights that the chronic use of cocaine is related to an increase in cardio- and cerebrovascular risk and probably to a greater incidence of psychomotor symptoms and neurodegenerative processes. Several studies have highlighted an increased risk of antipsychotic-induced extrapyramidal symptoms (EPSs) in patients with psychotic spectrum disorders comorbid with psychostimulant abuse. EPSs include movement dysfunction such as dystonia, akathisia, tardive dyskinesia, and characteristic symptoms of Parkinsonism such as rigidity, bradykinesia, and tremor. In the present paper, we propose a model of interpretation of the neurobiological mechanisms underlying the hypothesized increased vulnerability in chronic cocaine abusers to neurodegenerative disorders with psychomotor symptoms. Specifically, we supposed that the chronic administration of cocaine produces significant neurobiological changes, causing a complex dysregulation of various neurotransmitter systems, mainly affecting subcortical structures and the dopaminergic pathways. We believe that a better understanding of these cellular and molecular mechanisms involved in cocaine-induced neuropsychotoxicity may have helpful clinical implications and provide targets for therapeutic intervention.

Cardiovascular Risks of Simultaneous Use of Alcohol and Cocaine-A Systematic Review

Background: The simultaneous use of cocaine and alcohol is highly prevalent and is associated with high numbers of emergency department admissions, primarily due to cardiovascular complications. Aims: To answer the question of whether the co-use of cocaine and alcohol increases the cardiovascular risk compared to the use of cocaine alone. Method: A systematic review of human studies comparing the cardiovascular risk of co-used cocaine and alcohol with the use of cocaine alone. Results: Despite a higher myocardial workload induced by the co-use of cocaine and alcohol and the potentiation of cocaine's cardiovascular effects by alcohol, the findings on the risk and severity of cardiovascular symptoms due to combined use are inconsistent. However, the co-use of cocaine and alcohol clearly leads to higher mortality. Interestingly, the presence of cocaethylene, a unique metabolite generated only via a pharmacokinetic interaction between alcohol and cocaine, carries an 18- to 25-fold increase over the absence of cocaethylene (cocaine-alone users) in the risk of sudden death and is associated with myocardial injury and cardiac arrest, probably due to the inhibition of cardiac ion channels by cocaethylene. Conclusion: Despite the inconsistency in some of the results, it is concluded that the co-use of cocaine and alcohol poses an additional risk of cardiovascular fatalities compared to the use of cocaine alone.

Crack Cocaine Use-Related Spinal Cord Infarct

In this study, we describe an unusual occurrence of spinal cord infarct associated with acute usage of crack cocaine. A 64-year-old male patient was brought to the hospital after being found down, displaying weakness in his lower extremities and positive for cocaine use on a urine toxicology test. The patient was administered intravenous fluids and evaluated for syncope and rhabdomyolysis. Upon initial medical assessment, the patient exhibited sensation loss up to the level of the mid-thigh, paraplegia, urinary retention, and decreased rectal sphincter tone. Neurological examination and neurological imaging were suggestive of acute spinal cord infarct.

Cocaine-Induced Four-Extremity Ischemia Caused by a Hypercoagulable State

The use of cocaine is associated with serious complications including coronary vasospasm and myocardial, renal, intestinal, and neurological ischemia. Among these feared complications lies limb ischemia which is a rare potential side effect of chronic cocaine use. We present the case of a 50-year-old female with an extensive history of cocaine use who developed ischemia in all four limbs. Imaging studies revealed pulmonary emboli, multisystem thromboses, and microhemorrhages in the brain. Laboratory studies were significant for leukocytosis, thrombocytopenia, schistocytes on blood smear, and normal rheumatologic and hematologic studies. The patient was diagnosed with cocaine-induced thrombotic microangiopathy and she was treated symptomatically and with continuous heparin infusion. However, she ultimately requested to be discharged home and was lost to follow-up. Cocaine-induced thrombotic microangiopathy has been reported in only a few other patients to date and although there are some theories describing the possible pathophysiology, a clearly defined explanation has not yet been widely accepted.

Illegal drugs and periodontal conditions

In recent years, the practice of dentistry and periodontology has become complicated by several risk factors, including the treatment of an increasing number of patients with substance use disorder. This review presents an update in the current literature of the impact of illegal drug use on periodontal conditions and their possible effect as risk factors or indicators. The main illegal drugs that may have an impact on periodontal health and conditions are described, including their effect, medical manifestations, risks, and the overall effect on oral health and on the periodontium. Where available, data from epidemiologic studies are analyzed and summarized. The clinical management of periodontal patients using illegal drugs is reported in a comprehensive approach inclusive of the detection of illicit drug users, screening, interviewing and counseling, the referral to treatment, and the dental and periodontal management. With regard to the impact of illegal substance use on periodontal conditions, there is moderate evidence that regular long-term use of cannabis is a risk factor for periodontal disease, manifesting as a loss of periodontal attachment, deep pockets, recessions, and gingival enlargements. Limited evidence also shows that the use of cocaine can cause a series of gingival conditions that mostly presents as chemical induced-traumatic lesions (application of cocaine on the gingiva) or necrotizing ulcerative lesions. There is a scarcity of data regarding the impact of other drug use on periodontal health. There is evidence to suggest that regular long-term use of cannabis is a risk factor for periodontal disease and that the use of cocaine can cause a series of periodontal conditions. The dental treatment of subjects that use illegal substances is becoming more common in the daily clinical practice of periodontists and other dental clinicians. When the clinicians encounter such patients, it is essential to manage their addiction properly taking into consideration the impact of it on comprehensive dental treatment. Further studies and clinical observations are required to obtain sound and definitive information.

Environmentally realistic concentrations of cocaine in seawater disturbed neuroendrocrine parameters and energy status in the marine mussel Perna perna

Cocaine (COC) is a powerful illicit drug frequently detected in the aquatic environment. COC acts by inhibiting the reuptake of dopamine (DOPA) and 5-hydroxytryptamine (5-HT - serotonin) and causes endocrine disturbances in mammals. This study investigated similar effects from cocaine exposure in the marine mussel Perna perna, as well as neurotoxicity and energy imbalances. Mussels were exposed to COC (0.2 μg.L^-1 and 2 μg.L^-1) for periods of 48, 96, and 168 h. Acetylcholinesterase (AChE) was measured in adductor muscle tissue to determine neurotoxicity, and neurotransmitter levels (DOPA and 5-HT), monoamine oxidase (MAO) and cyclooxygenase (COX) activity, and energy status (mitrochondrial electron transport, MET, and total lipids, TLP) were evaluated in the mussels' gonads. COC decreased AChE activity in the mussels exposed to 0.2 μg.L^-1 and 2 μg.L -1 after 168 h, and all concentrations of COC increased neurotransmitter levels. Increases in MET (0.2 μg.L -1, for all exposure periods) and TLP (0.2 μg.L 1 after 48 h, and 2 μg.L -1 after 96 h and 168 h) were also observed. No significant change was detected in MAO activity. COC also decreased COX activity in the mussels exposed to 0.2 μg.L -1 (48 h and 96 h) and 2 μg.L -1 (96 h). These results suggest that COC may compromise neurotransmitter levels and COX activity. Furthermore, the changes in MET and LPT suggest that COC affects the energy balance of the mussels, and could negatively affect physiological processes such as metabolism, hormone production, and embryonic development.

A Positive Cocaine Urine Toxicology Test and the Effect on Intraoperative Hemodynamics Under General Anesthesia

BACKGROUND

Cocaine has a short biological half-life, but inactive urine metabolites may be detectable for a week following use. It is unclear if patients who test positive for cocaine but have a normal electrocardiogram and vital signs have a greater percentage of hemodynamic events intraoperatively.

METHODS

A total of 328 patients with a history of cocaine use who were scheduled for elective noncardiac surgery under general anesthesia were enrolled. Patients were categorized into cocaine-positive versus cocaine-negative groups based on the results of their urine cocaine toxicology test. The primary aim of this study was to evaluate whether asymptomatic cocaine-positive patients had similar percentages of intraoperative hemodynamic events, defined as (1) a mean arterial blood pressure (MAP) of <65 or >105 mm Hg and (2) a heart rate (HR) of <50 or >100 beats per minute (bpm) compared to cocaine-negative patients. The study was powered to assess if the 2 groups had an equivalent mean percent of intraoperative hemodynamic events within specific limits using an equivalence test of means consisting of 2 one-sided tests.

RESULTS

The cocaine-positive group had a blood pressure (BP) that was outside the set limits 19.4% (standard deviation [SD] 17.7%) of the time versus 23.1% (SD 17.7%) in the cocaine-negative group (95% confidence interval [CI], 0.5-7.0). The cocaine-positive group had a HR outside the set limits 9.6% (SD 16.2%) of the time versus 8.2% (SD 14.9%) in the cocaine-negative group (95% CI, 4.3-1.5). Adjusted for age, sex, body mass index (BMI), smoking status, and the presence of comorbid hypertension, renal disease, and psychiatric illness, the cocaine-positive and cocaine-negative patients were similar within a 7.5% margin of equivalence for MAP data (β coefficient = 2%, P = .003, CI, 2-6) and within a 5% margin of equivalence for HR data (β coefficient = 0.2%, P < .001, CI, 4-3).

CONCLUSIONS

Asymptomatic cocaine-positive patients undergoing elective noncardiac surgery under general anesthesia have similar percentages of intraoperative hemodynamic events compared to cocaine-negative patients.

Cocaine, cardiomyopathy, and heart failure: a systematic review and meta-analysis

Although the cardiotoxic effects of cocaine are universally recognized, the association between cocaine and cardiomyopathy and/or heart failure is poorly understood. To conduct a comprehensive review and meta-analysis on the association between cocaine, heart failure, and cardiomyopathy, we first conducted a broad-term search in PubMed, Embase, Web of Science, and Scopus for human studies containing primary data on the relationship between cocaine and heart failure or cardiomyopathy. We were interested in studies with data beyond acute coronary syndromes. Retrieved studies were grouped into different categories based on possible hypotheses to test by meta-analysis. A second search with specific terms was then conducted. For grouped studies with sufficient clinical and methodological homogeneity, effect sizes were calculated and combined for meta-analysis by the Random Effects model. There is in general a need for more primary data studies that investigate heart failure and/or cardiomyopathy in cocaine users for mechanisms independent of ischemia. There were, however, enough studies to combine by meta-analyses that showed that chronic cocaine use is associated with anatomical and functional changes more consistent with diastolic heart failure instead of the commonly taught dilated cardiomyopathy pathway. In patients without a history of ACS, chronic cocaine use was not associated with significantly reduced EF. The few studies on acute cocaine had conflicting results on whether single-dose intravascular cocaine results in acute heart failure. Studies identified that included beta-blockade therapy in cocaine users with cardiac disease suggest that beta-blockers are not unsafe and that may be effective in the treatment of cocaine-associated heart failure. Chronic cocaine use is associated with anatomical and physiological changes of the heart muscle that are potentially reversible with beta-blockade therapy.

Forensic Drug Profile: Cocaethylene

This article is intended as a brief review or primer about cocaethylene (CE), a pharmacologically active substance formed in the body when a person co-ingests ethanol and cocaine. Reference books widely used in forensic toxicology contain scant information about CE, even though this cocaine metabolite is commonly encountered in routine casework. CE and cocaine are equi-effective at blocking the reuptake of dopamine at receptor sites, thus reinforcing the stimulant effects of the neurotransmitter. In some animal species, the LD50 of CE was lower than for cocaine. CE is also considered more toxic to the heart and liver compared with the parent drug cocaine. The plasma elimination half-life of CE is ~2 h compared with ~1 h for cocaine. The concentrations of CE in blood after drinking alcohol and taking cocaine are difficult to predict and will depend on the timing of administration and the amounts of the two precursor drugs ingested. After an acute single dose of cocaine and ethanol, the concentration–time profile of CE runs on a lower level to that of cocaine, although CE is detectable in blood for several hours longer. A strong case can be made for adding together the concentrations of cocaine and CE in forensic blood samples when toxicological results are interpreted in relation to acute intoxication and the risk of an overdose death.

Participation of voltage-gated sodium and calcium channels in the acute cardiac effects of toluene

Inhaling solvents can lead to occurrence of cardiac arrhythmias and sudden sniffing death. Mechanisms related to this phenomenon are not fully understood. The purpose of this study was to investigate the effect of acute toluene exposure on heart reactivity to epinephrine and the participation of voltage-gated sodium and calcium channels. We found that acute toluene exposure increased perfusion pressure, left ventricular developed pressure, and heart rate. These actions were inhibited by lidocaine and nifedipine. Our results suggest that acute toluene exposure modify voltage-gated sodium and calcium channel function and expression likely due to a cardiac adrenergic mechanism and these effects could be participating, at least in part, in the presence of cardiac arrhythmias. To our best knowledge, this is the first report to establish a direct participation of voltage-gated Na⁺ and Ca²⁺ channels, toluene and epinephrine on cardiac function in rats.

An exploratory study of information sources and key findings on UK cocaine-related deaths

Cocaine-related deaths have increased since the early 1990s in Europe, including the UK. Being multi-factorial, they are difficult to define, detect and record. The European Monitoring Centre for Drugs and Drug Addiction commissioned research to: describe trends reported to Special Mortality Registries and General Mortality Registers; provide demographic and drug-use characteristic information of cases; and establish how deaths are identified and classified. A questionnaire was developed and piloted amongst all European Monitoring Centre for Drugs and Drug Addiction Focal Point experts/Special Mortality Registries: 19 (63%) responded; nine countries provided aggregated data. UK General Mortality Registers use cause of death and toxicology to identify cocaine-related deaths. Categorisation is based on International Classification of Diseases codes. Special Mortality Registries use toxicology, autopsy, evidence and cause of death. The cocaine metabolites commonly screened for are: benzoylecgonine, ecgonine methyl ester, cocaethylene and ecgonine. The 2000s saw a generally accelerating upward trend in cases, followed by a decline in 2009. The UK recorded 2700-2900 deaths during 1998-2012. UK Special Mortality Registry data (2005-2009) indicate: 25-44 year-olds account for 74% of deaths; mean age=34 (range 15-81) years; 84% male. Cocaine overdoses account for two-thirds of cases; cocaine alone being mentioned/implicated in 23% in the UK. Opioids are involved in most (58%) cocaine overdose cases.

Vascular disease in cocaine addiction

Cocaine, a powerful vasoconstrictor, induces immune responses including cytokine elevations. Chronic cocaine use is associated with functional brain impairments potentially mediated by vascular pathology. Although the Crack-Cocaine epidemic has declined, its vascular consequences are increasingly becoming evident among individuals with cocaine use disorder of that period, now aging. Paradoxically, during the period when prevention efforts could make a difference, this population receives psychosocial treatment at best. We review major postmortem and in vitro studies documenting cocaine-induced vascular toxicity. PubMed and Academic Search Complete were used with relevant terms. Findings consist of the major mechanisms of cocaine-induced vasoconstriction, endothelial dysfunction, and accelerated atherosclerosis, emphasizing acute, chronic, and secondary effects of cocaine. The etiology underlying cocaine's acute and chronic vascular effects is multifactorial, spanning hypertension, impaired homeostasis and platelet function, thrombosis, thromboembolism, and alterations in blood flow. Early detection of vascular disease in cocaine addiction by multimodality imaging is discussed. Treatment may be similar to indications in patients with traditional risk-factors, with few exceptions such as enhanced supportive care and use of benzodiazepines and phentolamine for sedation, and avoiding β-blockers. Given the vascular toxicity cocaine induces, further compounded by smoking and alcohol comorbidity, and interacting with aging of the crack generation, there is a public health imperative to identify pre-symptomatic markers of vascular impairments in cocaine addiction and employ preventive treatment to reduce silent disease progression.

Systems-level view of cocaine addiction: the interconnection of the immune and nervous systems

The human body is a complex assembly of physiological systems designed to manage the multidirectional transport of both information and nutrients. An intricate interplay between the nervous, circulatory, and secretory systems is therefore necessary to sustain life, allow delivery of nutrients and therapeutic drugs, and eliminate metabolic waste products and toxins. These systems also provide vulnerable routes for modification by substances of abuse. Addictive substances are, by definition, neurologically active, but as they and their metabolites are spread throughout the body via the nervous, circulatory, respiratory and digestive systems, there is abundant opportunity for interaction with numerous cell and tissue types. Cocaine is one such substance that exerts a broad physiological effect. While a great deal of the research concerning addiction has addressed the neurological effects of cocaine use, only a few studies have been aimed at delineating the role that cocaine plays in various body systems. In this paper, we probe the current research regarding cocaine and the immune system, and map a systems-level view to outline a broader perspective of the biological response to cocaine. Specifically, our overview of the neurological and immunomodulatory effects of the drug will allow a broader perspective of the biological response to cocaine. The focus of this review is on the connection between the nervous and immune systems and the role this connection plays in the long-term complications of cocaine use. By describing the multiplicity of these connections, we hope to inspire detailed investigations into the immunological interplay in cocaine addiction.

Cardiac Fas-dependent and mitochondria-dependent apoptosis after chronic cocaine abuse

To evaluate whether chronic cocaine abuse will increase cardiac Fas-dependent and mitochondria-dependent apoptotic pathways, thirty-two male Wistar rats at 3–4 months of age were randomly divided into a vehicle-treated group (phosphate-buffered saline, PBS, 0.5 mL, SQ per day) and a cocaine-treated group (Cocaine, 10 mg/kg, SQ per day). After 3 months of treatment, the excised left ventricles were measured by H&E staining, Western blotting, DAPI staining and TUNEL assays. More cardiac TUNEL-positive apoptotic cells were observed in the Cocaine group than the PBS group. Protein levels of TNF-alpha, Fas ligand, Fas death receptor, FADD, activated caspase-8, and activated caspase-3 (Fas-dependent apoptosis) extracted from excised hearts in the Cocaine group were significantly increased, compared to the PBS group. Protein levels of cardiac Bax, cytosolic cytochrome c, t-Bid-to-Bid, Bak-to-Bcl-xL, Bax-to-Bcl-2 ratio, activated caspase-9, and activated caspase-3 (mitochondria-dependent apoptosis) were significantly increased in the Cocaine group, compared to the PBS group. Chronic cocaine exposure appeared to activate the cardiac Fas-dependent and mitochondria-dependent apoptosis, which may indicate a possible mechanism for the development of cardiac abnormalities in humans with chronic cocaine abuse.

Cocaine synergism with α agonists in rat aorta: computational analysis reveals an action beyond reuptake inhibition

BACKGROUND

Cocaine has long been known to increase blood pressure, but the degree and mechanism of vasoconstricting action remain poorly understood. Here we examine the interaction between cocaine and alpha-adrenoceptor agonists, with the action of reuptake inhibition minimized.

METHODS

Cocaine was administered to isolated rings of rat thoracic aorta, alone and in combination with three different adrenoceptor agonists: phenylephrine, methoxamine, and norepinephrine. Synergy analysis begins with the predicted additive effect of the combination of two agonists, based upon dose equivalence theory. This case where one agonist (cocaine) has no effect when administered alone requires only a t-test to demonstrate that a departure from additivity has occurred.

RESULTS

At doses where cocaine alone produced no vasoconstriction, it potentiated the vasoconstriction produced by all three alpha agonists, a clear indication of synergism between cocaine and these agents. Higher doses of cocaine in combination with alpha adrenoceptor agents gave an inverted-U shaped (hormetic) dose-effect curve, i.e., dose-related relaxation at higher doses. The hormetic dose-effect relation was analyzed using computational methodology based on dose equivalence to derive the unknown second component of action that causes relaxation.

CONCLUSIONS

Cocaine exhibits both vasoconstricting and vasorelaxant effects. This relaxing component, possibly related to activation of myosin light chain phosphatase, was quantified as a dose-effect curve. Most important is the synergism between cocaine and alpha-adrenoceptor stimulation which cannot be explained as an action due to reuptake inhibition, and has not been previously described.

Characterization of differential cocaine metabolism in mouse and rat through metabolomics-guided metabolite profiling

Rodent animal models have been widely used for studying neurologic and toxicological events associated with cocaine abuse. It is known that the mouse is more susceptible to cocaine-induced hepatotoxicity (CIH) than the rat. However, the causes behind this species-dependent sensitivity to cocaine have not been elucidated. In this study, cocaine metabolism in the mouse and rat was characterized through LC-MS-based metabolomic analysis of urine samples and were further compared through calculating the relative abundance of individual cocaine metabolites. The results showed that the levels of benzoylecgonine, a major cocaine metabolite from ester hydrolysis, were comparable in the urine from the mice and rats treated with the same dose of cocaine. However, the levels of the cocaine metabolites from oxidative metabolism, such as N-hydroxybenzoylnorecgonine and hydroxybenzoylecgonine, differed dramatically between the two species, indicating species-dependent cocaine metabolism. Subsequent structural analysis through accurate mass analysis and LC-MS/MS fragmentation revealed that N-oxidation reactions, including N-demethylation and N-hydroxylation, are preferred metabolic routes in the mouse, while extensive aryl hydroxylation reactions occur in the rat. Through stable isotope tracing and in vitro enzyme reactions, a mouse-specific α-glucoside of N-hydroxybenzoylnorecgonine and a group of aryl hydroxy glucuronides high in the rat were identified and structurally elucidated. The differences in the in vivo oxidative metabolism of cocaine between the two rodent species were confirmed by the in vitro microsomal incubations. Chemical inhibition of P450 enzymes further revealed that different P450-mediated oxidative reactions in the ecgonine and benzoic acid moieties of cocaine contribute to the species-dependent biotransformation of cocaine.

Lipidomic profiling reveals protective function of fatty acid oxidation in cocaine-induced hepatotoxicity

During cocaine-induced hepatotoxicity, lipid accumulation occurs prior to necrotic cell death in the liver. However, the exact influences of cocaine on the homeostasis of lipid metabolism remain largely unknown. In this study, the progression of subacute hepatotoxicity, including centrilobular necrosis in the liver and elevation of transaminase activity in serum, was observed in a three-day cocaine treatment, accompanying the disruption of triacylglycerol (TAG) turnover. Serum TAG level increased on day 1 of cocaine treatment but remained unchanged afterwards. In contrast, hepatic TAG level was elevated continuously during three days of cocaine treatment and was better correlated with the development of hepatotoxicity. Lipidomic analyses of serum and liver samples revealed time-dependent separation of the control and cocaine-treated mice in multivariate models, which was due to the accumulation of long-chain acylcarnitines together with the disturbances of many bioactive phospholipid species in the cocaine-treated mice. An in vitro function assay confirmed the progressive inhibition of mitochondrial fatty acid oxidation after the cocaine treatment. Cotreatment of fenofibrate significantly increased the expression of peroxisome proliferator-activated receptor α (PPARα)-targeted genes and the mitochondrial fatty acid oxidation activity in the cocaine-treated mice, resulting in the inhibition of cocaine-induced acylcarnitine accumulation and other hepatotoxic effects. Overall, the results from this lipidomics-guided study revealed that the inhibition of fatty acid oxidation plays an important role in cocaine-induced liver injury.

Fatalities temporally associated with the ingestion of ibogaine

Ibogaine is a naturally occurring psychoactive plant alkaloid that is used globally in medical and nonmedical settings for opioid detoxification and other substance use indications. All available autopsy, toxicological, and investigative reports were systematically reviewed for the consecutive series of all known fatalities outside of West Central Africa temporally related to the use of ibogaine from 1990 through 2008. Nineteen individuals (15 men, four women between 24 and 54 years old) are known to have died within 1.5-76 h of taking ibogaine. The clinical and postmortem evidence did not suggest a characteristic syndrome of neurotoxicity. Advanced preexisting medical comorbidities, which were mainly cardiovascular, and/or one or more commonly abused substances explained or contributed to the death in 12 of the 14 cases for which adequate postmortem data were available. Other apparent risk factors include seizures associated with withdrawal from alcohol and benzodiazepines and the uninformed use of ethnopharmacological forms of ibogaine.

Effect of Ocimum sanctum, ascorbic acid, and verapamil on macrophage function and oxidative stress in mice exposed to cocaine

OBJECTIVE

To investigate the effect of Ocimum sanctum, ascorbic acid, and verapamil on macrophage function and oxidative stress in experimental animals exposed to cocaine.

MATERIALS AND METHODS

Mice were used in this study and were divided randomly into different groups of six animals each. They were either treated with intraperitoneal injection of saline or cocaine hydrochloride or an oral feeding of oil of Ocimum sanctum, ascorbic acid or verapamil, or both (ascorbic acid and verapamil), and were evaluated for a respiratory burst of macrophages, superoxide and nitric oxide (NO) production, estimation of TNF-alpha in the serum and supernatant of cultured macrophages, estimation of lipid peroxidation (malondialdehyde- MDA) in the serum, and superoxide dismutase activity in the erythrocytes.

RESULTS

Unstimulated respiratory burst as well as superoxide production was enhanced on treatment with cocaine and all the three drugs were found to attenuate this enhancement. The bactericidal capacity of macrophages decreased significantly on chronic cocaine exposure, as it was associated with decreased respiratory burst and superoxide production. There was a significant decrease in NO production by macrophages on chronic cocaine exposure and all the test drugs were found to restore nitrite formation to a normal level. There was an increase in the malonylodialdehyde (MDA) level and decrease in the superoxide dismutase level on chronic cocaine exposure, and all the three drugs effectively decreased the MDA level and increased superoxide dismutase level. There was an increase in serum TNF-alpha on chronic cocaine exposure, which was decreased significantly by ascorbic acid and verapamil.

CONCLUSION

O. sanctum, ascorbic acid, and verapamil were equally effective in improving the macrophage function and reducing oxidative stress. These findings suggested that O. sanctum, ascorbic acid, and verapamil attenuated acute and chronic cocaine-mediated effects.

Putting cocaine use and cocaine-associated cardiac arrhythmias into epidemiological and clinical perspective

This is the first article in a series of three articles on cocaine-related cardiac arrhythmias, following on from the 2008 British Pharmacological Society Winter Meeting Clinical Section Symposium entitled 'Cocaine induced cardiac arrhythmias - from ion channel to clinical treatment'. We will summarize the epidemiology of cocaine use across the world and in particular will focus on UK, Europe and US use prevalence data. We will discuss the acute cardiac and non-cardiac toxicity associated with cocaine and highlight the lack of data on the true UK prevalence of acute cocaine toxicity and on the incidence of cocaine-related cardiac arrhythmias.

Role of voltage-gated sodium, potassium and calcium channels in the development of cocaine-associated cardiac arrhythmias

Cocaine is a highly active stimulant that alters dopamine metabolism in the central nervous system resulting in a feeling of euphoria that with time can lead to addictive behaviours. Cocaine has numerous deleterious effects in humans including seizures, vasoconstriction, ischaemia, increased heart rate and blood pressure, cardiac arrhythmias and sudden death. The cardiotoxic effects of cocaine are indirectly mediated by an increase in sympathomimetic stimulation to the heart and coronary vasculature and by a direct effect on the ion channels responsible for maintaining the electrical excitability of the heart. The direct and indirect effects of cocaine work in tandem to disrupt the co-ordinated electrical activity of the heart and have been associated with life-threatening cardiac arrhythmias. This review focuses on the direct effects of cocaine on cardiac ion channels, with particular focus on sodium, potassium and calcium channels, and on the contributions of these channels to cocaine-induced arrhythmias. Companion articles in this edition of the journal examine the epidemiology of cocaine use (Wood & Dargan) and the treatment of cocaine-associated arrhythmias (Hoffmann).

Behavioral cross-sensitization between DOCA-induced sodium appetite and cocaine-induced locomotor behavior

Behavioral sensitization involves increases in the magnitude of a response to a stimulus after repeated exposures to the same response initiator. Administration of psychomotor stimulants and the induction of appetitive motivational states associated with natural reinforcers like sugar and salt are among experimental manipulations producing behavioral sensitization. In rats, repeated administration of the mineralocorticoid agonist deoxycorticosterone acetate (DOCA) initially induces incremental increases in daily hypertonic saline consumption (i.e., sensitization of sodium appetite) in spite of the retention of sodium. The present studies investigated whether sodium appetite sensitization induced by DOCA shares mechanisms similar to those of psychomotor stimulant-induced sensitization, and whether there is evidence for reciprocal cross-sensitization. In Experiments 1 and 3, rats received control or cocaine treatments to induce locomotor sensitization. A week later DOCA (or vehicle) was administered to generate a sodium appetite. Animals pretreated with cocaine showed a greater sodium appetite. In Experiment 2, the order of the putative sensitizing treatments was reversed. Rats first received either a series of DOCA or vehicle treatments either with or without access to saline and were later tested for sensitization of the locomotor response to cocaine. Animals pretreated with DOCA without access to saline showed greater locomotor responses to cocaine than animals receiving vehicle treatments. Together these experiments indicate that treatments generating a sustained salt appetite and producing cocaine-induced psychomotor responses show reciprocal behavioral cross-sensitization. The underlying mechanisms accounting for this relationship may be the fact that psychostimulants and an unresolved craving for sodium can act as potent stressors.

Agonist-like pharmacotherapy for stimulant dependence: preclinical, human laboratory, and clinical studies

A variety of natural and synthetic agents have long been used for stimulant properties, with nontherapeutic use producing multiple waves of stimulant abuse and dependence. The multitude of effects of stimulants exist on continua, and accordingly, here we characterize stimulant abuse/dependence and candidate pharmacotherapies in this manner. Behavioral therapy and medications have been investigated for treatment of stimulant abuse/dependence. Effectiveness of some behavioral interventions has been demonstrated. Most medications studied have been found to lack efficacy. However, an expanding literature supports use of agonist-like medications to treat stimulant abuse/dependence, a strategy effective for nicotine and opiate dependence. The agonist-like conceptualization for stimulant dependence posits that medications with properties similar to that of the abused drug, but possessing lesser abuse liability, will normalize neurochemistry and stabilize behavior, thus reducing drug use. Data suggest use of a range of medications, from l-dopa/carbidopa to amphetamine preparations, depending on the severity of use. This report reviews preclinical, human laboratory, and clinical trial data supporting the agonist-like approach, including risks and benefits. Future directions for development of agonist-like medications are also discussed.

The effect of olanzapine pretreatment on acute cocaine toxicity in mice

BACKGROUND

Acute cocaine poisoning causes neuroexcitation and can be fatal. The toxic effects of cocaine can be attenuated by antagonists of serotonin, muscarinic cholinergic, and dopamine receptors. Olanzapine, an atypical antipsychotic medication, is an antagonist of these receptors. The objective of this study is to evaluate the efficacy of olanzapine pretreatment for attenuation of acute cocaine toxicity using a mouse model.

METHODS

Eighty male CF-1 mice were randomly assigned to olanzapine (1 mg/kg) or placebo pretreatment. Fifteen minutes later, all animals received 103 mg/kg intraperitoneal cocaine.

RESULTS

Overall mortality was 11% for olanzapine-treated animals and 45% for placebo. Olanzapine also appeared to alter the characteristics of seizures due to cocaine.

CONCLUSIONS

In this model of acute cocaine toxicity, olanzapine pretreatment attenuated acute cocaine toxicity. Olanzapine should be evaluated further as a potential treatment for acute cocaine poisoning.

An analysis of cocaine powder in the Netherlands: content and health hazards due to adulterants

AIMS

To report on trends in the content and adulterants present in street cocaine (powder) in the Netherlands and to describe the associated health hazards.

DESIGN AND PARTICIPANTS

Drug consumers handed in samples of cocaine powder from 1999 to 2007 for analysis. Reports were compiled of users' experiences with the samples received.

MEASUREMENTS AND ANALYSIS

Linear regression analysis was used to assess the trend in adulterated cocaine powder across the study period, and comparison of reported adverse effects of adulterated with those of unadulterated cocaine by Fisher's exact test.

FINDINGS

There has been a statistically significant upward trend in the occurrence of adulterated cocaine powder over the years. Adulterated cocaine was associated more frequently with reported adverse effects than unadulterated cocaine. Phenacetin, hydroxyzine and diltiazem appeared to be three adulterants contributing to these adverse effects.

CONCLUSIONS

An increase in adulterants was detected in the analysed cocaine powder between 1999 and 2007. This increase is associated with relatively more adverse effects with cocaine use. The cardiac and hallucinatory effects that were reported more frequently are not understood clearly. Adverse effects are likely to be due to several factors, including interactions of adulterants with cocaine and the route of administration.

Cocaine: history, social implications, and toxicity: a review

The amount of positive cocaine results in an urban emergency department are staggering. The ages of use are becoming more common in older age groups. Most of these patients have underlying medical conditions, including end-stage renal disease (on hemodialysis) and heart and lung disease. Most of their visits to the emergency department are for cocaine exacerbation of underlying chronic condition, adding exponentially to health care dollars. This article describes the history and pharmacology of illicit cocaine use.

Angiotensin and NMDA receptors in the median preoptic nucleus mediate hemodynamic response patterns to stress

The brain renin-angiotensin system plays an important role in the regulation of arterial pressure in response to stress, in part due to activation of AT1 receptors in the hypothalamic median preoptic nucleus (MnPO) by endogenous angiotensin II (ANG II). N-methyl-d-aspartate (NMDA) receptors are also involved in the angiotensinergic signaling pathway through the MnPO. We investigated whether AT1 and NMDA receptors in the MnPO are responsible for variable hemodynamic response patterns to stress. Cocaine or startle with cold water evoked a pressor response in Sprague-Dawley rats due, in some rats [vascular responders (VR)], to a large increase in systemic vascular resistance (SVR) and, in other rats [mixed responders (MR)], to small increases in SVR and cardiac output (CO). Microinjection of the GABAA agonist muscimol into the MnPO to block synaptic transmission attenuated the cocaine- or stress-induced increase in SVR and the decrease in CO seen in VR without altering either response in MR. Likewise, administration of either an AT1 receptor antagonist, losartan, or an NMDA receptor antagonist, MK-801, attenuated the increase in SVR and the decrease in CO in VR in response to either cocaine (losartan and MK-801) or startle with cold water (losartan) without altering either response in MR. We propose that the MnPO is responsible for greater SVR responses in VR and that AT1 and NMDA receptors play an important role in greater SVR responses in VR. These data provide additional support for the critical role of the MnPO in cardiovascular responses to stress.

Cocaine/crack cocaine consumption, treatment demand, seizures, related offences, prices, average purity levels and deaths in the UK (1990 - 2004)

A recent trend of escalating use of cocaine/crack cocaine was observed in the UK. The number of mentions on death certificates; last year use of cocaine; treatment demand, number of drug offenders, seizures, prices and average purity levels were the indicators used for this descriptive and correlational study. Figures (1990-2004) were taken from official UK sources. A total of 1022 cocaine/crack cocaine death mentions (i.e. deaths from any cause where the presence of cocaine/crack cocaine was also detected) were identified, with cocaine/crack cocaine being the sole drug mentioned in 36% of cases. The number of cocaine/crack cocaine death mentions showed a year-on-year increase and correlated positively with the following cocaine (powder) figures: last year use (p < 0.001); number of offenders (p < 0.001) and number of seizures (p < 0.001), but correlated negatively with price (p < 0.001). Furthermore, the number of cocaine/crack cocaine death mentions correlated positively with the number of crack offenders (p < 0.001) and seizures (p < 0.001), but correlated negatively with both crack purity ( p < 0.001) and price (p < 0.05). With conditions of increasing drug availability having been met in the UK, decrease in cocaine prices were associated with higher consumption levels and this, in turn, contributed to the increase in number of cocaine-related fatalities. There are limitations with the information collected, since no distinction is usually made on medical death certificates between cocaine and crack cocaine. The present study being an ecological one, it proved difficult to address the role of confounding variables that may well explain some of the associations observed.

Interpretation of lesions of the cardiac conduction system in cocaine-related fatalities

This study examines cases of chronic drug users who died suddenly after drug administration. Victims were young subjects, aged from 19 to 35 from Switzerland and known to the police as long-term drug users. The circumstances of death suggested the occurrence of a sudden, unexpected death. Some victims were undergoing methadone treatment. In each case, a forensic autopsy and toxicological analyses were performed at the Institute of Forensic Medicine in Lausanne in Switzerland between 2002 and 2004, including hair analysis as a means to establish chronic drug use in general, and cocaine use in particular. The conduction system was examined histologically and cases showing potentially lethal changes were chosen for this report. The most frequent lesions found were severe thickening of the atrioventricular node artery, intranodal and perinodal fibrosis, and microscopic foci of chronic inflammatory infiltration. The authors conclude that pathological lesions in the conduction tissue may play a role in the occurrence of death attributed to intoxication consecutive to cocaine ingestion.

Cannabis and cocaine: a lethal cocktail triggering coronary sudden death

The case of a 31-year-old man who died suddenly, with a history of drug abuse and no risk factors for coronary artery disease, is herein reported. Postmortem examination disclosed critical stenosis due to a fibrocellular atherosclerotic plaque complicated by occlusive thrombosis at the level of the left anterior descending coronary artery. Chemico-toxicological analysis revealed high levels of cocaine, tetrahydrocannabinol, and metabolites. When dealing with an acute coronary syndrome in young people, with or without a history of drug abuse, toxicological examination should always be performed to rule out unnatural causes of myocardial ischemia.

Clonidine attenuates morphine withdrawal and subsequent drug sensitization in rhesus monkeys

AIM

Clonidine is an alpha2 adrenoceptor agonist that is frequently used to reduce withdrawal symptoms during opioid detoxification in humans. The long-term effects of clonidine on withdrawal symptoms and its effects on subsequent drug exposure have not been thoroughly documented. The aim of the study was to determine if clonidine administered during morphine withdrawal in rhesus monkeys produces long-lasting effects on withdrawal symptoms and alters the effects of subsequently taken drugs of abuse.

METHODS

Adult male rhesus monkeys were treated with increasing doses of morphine for 90 d to induce opiate (narcotic) dependence. The immediate and long-lasting effects of 1 week's administration of clonidine were measured via the recording of morphine withdrawal signs and the subsequent effects of challenge injections of morphine or cocaine.

RESULTS

Monkeys chronically treated with morphine displayed withdrawal signs that lasted 2 weeks after cessation of morphine administration and displayed sensitized responses to subsequent morphine and cocaine injections. Clonidine significantly reduced certain morphine withdrawal signs and overall withdrawal score, but these effects did not persist upon cessation of clonidine treatment. Sensitization to the effects of morphine and cocaine were significantly reduced in monkeys previously treated with clonidine.

CONCLUSION

Our results suggest that in addition to its short-term alleviating effect on morphine withdrawal signs, clonidine may reduce subsequent effects of drugs of abuse after prolonged abstinence.

Rapid and robust protection against cocaine-induced lethality in rats by the bacterial cocaine esterase

There is no approved means to prevent the toxic actions of cocaine. Cocaine esterase (CocE) is found in a rhodococcal strain of bacteria that grows in the rhizosphere soil around the coca plant and has been found to hydrolyze cocaine in vitro. The esteratic activity of CocE (0.1-1.0 mg, i.v.) was characterized and confirmed in vivo by assessing its ability to prevent cocaine-induced convulsions and lethality in the rat. The therapeutic efficiency of the enzyme was demonstrated by the increasing dose of cocaine (100-1000 mg/kg, i.p.) required to produce toxic effects after a single intravenous injection of CocE. The enzyme demonstrated rapid kinetics for cocaine degradation in rat and human serum. Two catalytically inactive mutants of CocE (S117A or Y44F) failed to protect rats from the toxic effects of cocaine, confirming the protective effects are due to hydrolytic activity. However, butyrylcholinesterase, an endogenous cocaine-hydrolyzing enzyme, was inactive (1.3-13 mg, i.v.) in this rat toxicity procedure. Furthermore, CocE did not block the lethality of WIN-35065-2 (560 mg/kg, i.p.), a cocaine analog that lacks the benzoyl ester moiety targeted by CocE. This characterization of CocE provides preliminary evidence that the enzyme could serve as a suitable antidote to cocaine toxicity in humans.

Central angiotensin II receptors mediate hemodynamic response variability to stressors

We examined whether ANG II receptors in the central nervous system mediate hemodynamic responses to pharmacological (cocaine) and behavioral (cold water) stressors. After administration of cocaine (5 mg/kg iv), rats were classified as vascular responders (VR) if their pressor response was due entirely to an increase in systemic vascular resistance (SVR) despite a decrease in cardiac output (CO). Cocaine elicited a pressor response in mixed responders (MR) that was dependent on small increases in both SVR and CO. ANG II (30 ng/5 μl icv, 5 min before cocaine) augmented the decrease in CO in VR and prevented the increase in CO in MR. Administration of [Sar1,Thr8]ANG II (20 μg/5 μl icv; sarthran) before cocaine attenuated the decrease in CO and the large increase in SVR in VR so that they were no longer different from MR. Losartan (20 μg icv) or captopril (50 μg icv) preceding cocaine administration also attenuated the decrease in CO and the large increase in SVR seen in VR only. The role of angiotensin was not specific for cocaine, because ANG II (icv) pretreatment before startle with cold water (1 cm deep) enhanced the decrease in CO and the increase in SVR in both MR and VR, whereas losartan (icv) pretreatment before startle attenuated the decrease in CO and the increase in SVR in VR so that they were no longer different from MR. These data suggest that central ANG II receptors mediate the greater vascular and cardiac responsiveness in vascular responders to acute pharmacological and behavioral stressors.

Comparing the physiological and subjective effects of self-administered vs yoked cocaine in humans

RATIONALE

Studies with laboratory animals demonstrating different effects of self- vs experimenter-administered drug suggest that the ability to control or predict drug delivery may be an important determinant of drug action.

OBJECTIVE

This study assessed whether self-administered and yoked cocaine injections produce different effects in humans.

METHODS

Ten inpatient volunteers with experience in using cocaine participated in a double-blind, yoked design during which four experimental test sessions were conducted. During two sessions, participants controlled if and when up to six 40 mg/70 kg i.v. cocaine injections were given. During two sessions, participants received noncontingent exposure to the same pattern of injections given during the preceding session (i.e., yoked) under blind conditions. Sessions followed a fixed-order, ABAB design. Measures of subjective and physiological response to cocaine were taken throughout each session.

RESULTS

Cardiovascular safety parameters were exceeded in some individuals after yoked, but not self-administered, cocaine resulting in some scheduled injections being delayed or withheld. Mean systolic and diastolic blood pressures were higher following yoked compared to self-administered cocaine. In contrast, analysis of the subjective effects revealed only small and generally nonsignificant differences in the effects of self-administered vs yoked cocaine.

CONCLUSIONS

These results suggest that under the laboratory methods employed, control over the schedule of drug delivery may not alter the subjective effects of cocaine in humans. In contrast, the cardiovascular effects of cocaine appear to be greater when the drug is administered noncontingently.

Intravenous Cocaine and QT Variability

BACKGROUND

Dynamic instability in cardiac repolarization may contribute to drug-induced arrhythmogenesis. We hypothesized that intravenous cocaine would significantly destabilize repolarization as measured by QT variability.

METHODS AND RESULTS

Twenty-nine cocaine-experienced volunteers not seeking treatment for cocaine addiction received randomized, sequential intravenous infusions of placebo or cocaine (20 and 40 mg). Five-minute epochs of digitized ECG were recorded 10 minutes before, during, and at intervals following the infusions. QT variability was measured using a semiautomated method and expressed as the log ratio of normalized QT variance to normalized heart rate variance (QTVI). Seventeen subjects received a repeat course of cocaine infusions 1 week later. Placebo infusion resulted in a small but significant increase in QTVI, while cocaine caused a highly significant, dose-dependent increase in QTVI that peaked at 10 minutes and dissipated by 45 minutes following infusion (P < 0.0001). The increase in QTVI was reproducible at 1 week (P = 0.8).

CONCLUSIONS

Cocaine injection results in a significant dose-dependent increase in QT variability as indexed by QTVI. This destabilizing effect on repolarization may increase vulnerability to reentrant arrhythmias and may partially explain an increased risk of sudden cardiac death associated with cocaine use.

The effect of amiodarone pretreatment on survival of mice with cocaine toxicity

INTRODUCTION

Cocaine is a common drug of abuse and use has been associated with ventricular dysrhythmias. Published guidelines suggest that amiodarone is the first line antidysrhythmic for ventricular tachycardia and fibrillation. However, the effects amiodarone in the setting of cocaine toxicity are unknown and unstudied. The purpose of this study was to evaluate the safety and efficacy of amiodarone pretreatment in a murine model of acute cocaine toxicity.

METHODS

This was a randomized, blinded, placebo controlled investigation using male CF-1 mice weighing 29-37 g. First, the safety of an intraperitoneal dose of amiodarone (40 mg/kg) was confirmed in 5 mice. Second, based on preliminary investigations, an approximate intraperitoneal LD50 dose of cocaine (110 mg/kg) was identified and used as the cocaine dose in this study. Animals were then randomized to 2 groups. The control group received 0.5 mL of intraperitoneal 0.9% saline 30 minutes before cocaine. The study group received 40 mg/kg of intraperitoneal amiodarone (40 mg/kg) 30 minutes before cocaine. A blinded observer monitored mice for 2 hours after cocaine administration.

RESULTS

No mice in the amiodarone-only group developed any signs of toxicity or died. In the saline + cocaine group 31/32 (96.9%; 95% CI 83.8 to 99.9) mice seized with a median time to seizure of 2.5 minutes, and 23/32 (71.9%; 95% CI 52.3 to 86.3) died with a median time to death of 5.5 minutes. In the amiodarone + cocaine group 31/33 (93.9%; 95% CI 79.0 to 99.3) mice seized with a median time to seizure of 2.0 minutes, and 24/33 (72.7%; 95% CI 54.5 to 86.7) died with a median time to death of 6.0 minutes. All animals that died did so within 9 minutes. The difference in the proportion of animals dying in the amiodarone + cocaine group compared to the saline + cocaine group was 0.008 (-21 to 22%).

CONCLUSIONS

In this study, pretreatment with amiodarone in cocaine poisoned mice resulted in no change in seizure incidenceor mortality. However, definite conclusions about the reason for these findings cannot be drawn from this model.

Central β-adrenoceptors mediate phasic and sustained components of hemodynamic responses to acute behavioral stress

Startle elicits a pattern of cardiovascular responses that is consistent within individual rats but varies between rats. We examined the hypothesis that central beta-adrenoceptors mediate differences in the hemodynamic responses to stress. Conscious rats exposed to cold water (1 cm deep, 1 min) had an initial phasic (startle) response (first 5 s) that varied considerably between rats. We designated those rats with an initial increase in cardiac output (CO) and systemic vascular resistance (SVR) as mixed responders while those with only an increase in SVR were vascular responders. Propranolol pretreatment (3 microg, icv) made the phasic changes in CO more negative, whereas isoproterenol (3 microg) made the CO response more positive in mixed responders and attenuated the increases in arterial pressure and SVR in vascular responders. Metoprolol (30 microg, icv) depressed the change in CO due to startle in mixed responders by decreasing heart rate. ICI 188,551 (25 microg, icv) did not alter the responses to startle but depressed the heart rate and CO responses and enhanced the pressor and SVR responses to sustained stress (1 min exposure to cold water). The results suggest that startle elicits hemodynamic responses that are primarily dependent on beta1-adrenoceptors but responses to sustained stress are dependent on beta2-adrenoceptors in the CNS.

Postnatal consequences of prenatal cocaine exposure and myocardial apoptosis: does cocaine in utero imperil the adult heart?

Cocaine use is common among pregnant women with a history of substance abuse, and has been shown to cause abnormalities in the heart during fetal and postnatal development. However, mechanisms underlying the detrimental effects of cocaine on the developing heart are not fully understood. In this issue, Bae and Zhang show that prenatal cocaine exposure increases the susceptibility of the postnatal heart to ischemia and reperfusion injury. Their results suggest that myocardial apoptosis induced by cocaine during fetal development may represent one of the mechanisms by which prenatal cocaine exposure exerts its long-term, deleterious consequences on postnatal cardiac function.

Role of angiotensin II and corticotropin-releasing hormone in hemodynamic responses to cocaine and stress

Cocaine produces characteristic behavioral and autonomic responses due to its unique pharmacological properties. Many of the autonomic responses resemble those to acute behavioral stress. Both cocaine and behavioral stress have been shown to evoke an increase in sympathetic nerve activity that is primarily responsible for the peripheral cardiovascular responses. We noted varying hemodynamic and sympathetic response patterns to cocaine administration and to acute behavioral stress in rats that correlate with the predisposition to develop both a sustained increase in arterial pressure and cardiomyopathies. Several lines of evidence suggest that the autonomic response patterns are dependent on the actions of central peptides including angiotensin II (Ang II) and corticotropin-releasing hormone (CRH). This is based on observations demonstrating that intracerebroventricular (icv) administration of receptor antagonists for Ang II or CRH attenuated the decrease in cardiac output (CO) and increase in vascular resistance noted in some animals after cocaine administration or startle. In contrast, icv Ang II enhances the cardiodepression associated with cocaine administration or startle. Based on this and other evidence, we propose that the autonomic response patterns to startle and to cocaine are closely related and dependent on central Ang II and CRH. Furthermore, we suggest that these central peptides may be responsible for varying predisposition to cardiovascular disease.

Peripartum care of the cocaine-abusing parturient: are we ready?

Cocaine abuse in the United States is widespread, affecting more than 30 million people. Nearly 90% of cocaine-abusing women are of childbearing age. Cardiovascular complications of cocaine intoxication include dysrhythmias, ischemia and/or infarction, and account for most cocaine-related deaths. Pregnancy enhances the cardiovascular toxicity of cocaine. While the epidemiology, pathophysiology, clinical symptomatology and implications on pregnancy of cocaine addiction in pregnancy have received significant attention over the past 25 years, far too little attention has been given to the therapeutic considerations and peripartum care of the cocaine-abusing parturients. The timely treatment of acute cocaine-induced cardiovascular toxicity in pregnancy is by far the best predictor of good maternal and fetal outcome. However, no specific treatment guidelines are currently available for cocaine-induced cardiac dysrhythmias. This article discusses briefly several agents (and considers their mechanism of action) that have been proposed for the treatment of chest pain and other cardiovascular side-effects of cocaine toxicity in pregnancy.

Mechanisms Underlying the Sympathomimetic Cardiovascular Responses Elicited by γ-Hydroxybutyrate

Gamma-hydroxybutyrate (GHB) is generally thought to be a central nervous system depressant; however, GHB also has sympathomimetic cardiovascular actions. Radio telemetry was used to record the cardiovascular responses elicited by GHB (180-1000 mg/kg IV) in conscious rats. GHB elicited increases in mean arterial pressure (MAP) (24 +/- 3 to 60 +/- 5 mm Hg) lasting from 28 +/- 8 to 227 +/- 37 minutes. GHB (560 and 1000 mg/kg IV) also elicited a prolonged tachycardic response (85 +/- 23 and 95 +/- 22 bpm). The hypertension and tachycardia elicited by GHB (560 mg/kg) were reversed by the intravenous and intracerebroventricular administration of the GABAb receptor antagonist CGP 35348. CGP 35348 also reversed GHB-mediated increases in renal sympathetic nerve activity (RSNA). Administration of the purported GHB receptor antagonist NCS-382 reversed the increase in heart rate but not the pressor response elicited by GHB in telemetered rats. These data indicate that the intravenous administration of GHB markedly increases MAP, heart rate, and RSNA in conscious rats via activation of central GABAb receptors. In addition, GHB receptors appear to selectively mediate the increase in heart rate elicited by large doses of GHB.

Haemodynamic responses to sensory stimulation are enhanced following acute cocaine administration

Cocaine enhances neural activity in response to sensory stimulation, an effect that may play a role in the development of drug craving. However, cocaine-induced sensory enhancement may be difficult to study in humans using neuroimaging if the global increases in baseline haemodynamic parameters, which cocaine produces, interfere with the ability of enhanced sensory-related neural activity to lead to enhanced haemodynamic responses. To investigate the effect of cocaine-induced baseline haemodynamic changes on sensory-related haemodynamic (and electrophysiological) responses, field potential (FP) and haemodynamic responses (obtained using optical imaging spectroscopy and laser-Doppler flowmetry) in the barrel cortex of the anaesthetised rat were measured during mechanical whisker stimulation following cocaine (0.5 mg/kg) or saline administration. During cocaine infusion, the relationship between blood flow and volume transiently decoupled. Following this, cocaine caused large baseline increases in blood flow (133%) and volume (33%), which peaked after approximately 6 min and approached normal levels again after 25 min. During the peak baseline increases, FP responses to whisker stimulation were similar to saline whereas several haemodynamic response parameters were slightly reduced. After the peak, significant increases in FP responses were observed, accompanied by significantly enhanced haemodynamic responses, even though the haemodynamic baselines remained elevated. Hence, the haemodynamic response to sensory stimulation is transiently reduced in the presence of large increases in baseline but, after the baseline peak, enhanced neural responses are faithfully accompanied by enhanced haemodynamic responses. The findings suggest that any cocaine-induced enhancement of sensory-related neural activity in humans is likely to be detectable by neuroimaging.

Closing and inactivation potentiate the cocaethylene inhibition of cardiac sodium channels by distinct mechanisms

Cocaethylene, a metabolite of cocaine and alcohol, is a potent inhibitor of the cardiac (Nav1.5) sodium channel heterologously expressed in Xenopus laevis oocytes. Cocaethylene produces minimal tonic block under resting conditions but causes a potent use-dependent inhibition during repetitive depolarization and a hyperpolarizing shift in the steady-state inactivation. The data are consistent with a state-dependent binding mechanism, which has high affinity for inactivated channels (KI = 17 microM) and low affinity for resting channels (KR = 185 micro). Mutations of the interdomain D3-D4 linker eliminated rapid inactivation and weakened the cocaethylene inhibition, consistent with an important role for fast inactivation in cocaethylene binding. A rapid component of cocaethylene inhibition was observed in a noninactivating mutant of Nav1.5 that was tightly linked to channel opening and displayed properties consistent with a pore blocking mechanism. Hyperpolarization caused the noninactivating mutant channel to close, trapping cocaethylene and slowing the recovery. Mutation of a conserved isoleucine (I1756C) located near the extracellular end of the D4S6 segment accelerated the recovery of the noninactivating channel, suggesting that this mutation facilitates cocaethylene untrapping, which seems to be the rate-limiting step in the recovery when the channel is closed. This contrasts with the rapidly inactivating channel, where the I1756C mutation did not alter the recovery from cocaethylene inhibition. The data suggest that additional mechanisms, such as more stable cocaethylene binding, may be a more important determinant of recovery kinetics when the channels are inactivated. The data indicate that deactivation and inactivation slow the recovery and potentiate the cocaethylene inhibition of the Nav1.5 channel by distinct mechanisms.

Cocaine enhances susceptibility to endotoxemic shock in a subset of rats

OBJECTIVE

We hypothesized that the sympathomimetic cocaine may alter cardiovascular and inflammatory responses and enhance susceptibility to endotoxemia due to innate differences in patterns of sympathetic and cardiovascular responsiveness.

DESIGN

Prospective study.

SETTING

Experimental animal laboratory.

SUBJECTS

Fifty-six conscious, instrumented albino rats.

INTERVENTIONS

Rats were instrumented for determination of arterial pressure and intravenous drug administration and, in some rats, for cardiac output. After recovery, rats were given cocaine (5 mg/kg i.v., twice daily with 4-6 trials) to identify one of two hemodynamic response patterns: a) an increase in systemic vascular resistance with cardiac depression (vascular responders) or b) smaller increases in systemic vascular resistance and no change or an increase in cardiac output (mixed responders). At least 1 month after characterizing response patterns to cocaine, animals were pretreated with cocaine (5 mg/kg i.v.) or an equivalent bolus of vehicle (0.9% saline) while recording hemodynamics. Five minutes later, Escherichia coli lipopolysaccharide (serotype O55:B5, 20 mg/kg i.v.) was administered for 15 mins.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic responses, pupillary diameter, and serum cytokines were determined at several time points. Lipopolysaccharide administration (5-40 mg/kg) without cocaine produced dose-dependent depressor responses with recovery typically within 2 hrs. Although 87% of rats survived a single 20 mg/kg dose of lipopolysaccharide when given alone, pretreatment of vascular responders with cocaine before lipopolysaccharide resulted in greater increases in systemic vascular resistance and pupillary mydriasis and lethality in five of six vascular responders, whereas only one of six mixed responders died. Pretreatment with the alpha1-adrenoceptor antagonist prazosin (0.1 mg/kg i.v.) before cocaine and lipopolysaccharide attenuated hemodynamic responses and improved survival among vascular responders. Serum interleukin-6 and interleukin-10 were elevated in rats treated with cocaine and lipopolysaccharide compared with rats treated with lipopolysaccharide alone, whereas serum tumor necrosis factor-alpha was reduced by cocaine pretreatment. Moreover, serum interleukin-1beta, tumor necrosis factor-alpha, and interleukin-6 were elevated in nonsurvivors compared with survivors after cocaine and lipopolysaccharide administration.

CONCLUSIONS

We conclude that cocaine enhances susceptibility and worsens outcome from endotoxic shock by augmenting sympathetic activity, particularly in vascular responders, and that alpha-adrenoceptors mediate the altered inflammatory responses.