Direct cardiotoxic effects of cocaine and cocaethylene on isolated cardiomyocytes

Acute Cocaine Toxicity: Pharmacology and Clinical Presentations in Adult and Pediatric Populations

Cocaine remains the most prevalent drug responsible for emergency department (ED) visits. A majority of acute cocaine toxicity cases involve young, habitual, adult cocaine users and often present with a range of cardiac, neurologic, gastrointestinal (GI) or renal symptoms. In addition, atypical populations (neonates, infants, toddlers, young children and adolescents) are presenting in EDs with varying symptoms that are unknowingly associated with cocaine exposure. Unfortunately, juvenile presentations are generally anecdotal in nature, and while enlightening, are difficult to quantify epidemiologically. Outlining the types of symptom presentation in these young populations may assist healthcare providers in expediting proper treatment for such demographic groups. Therefore, this review examines the current knowledge regarding cocaine's pharmacologic activity as it relates to its potential toxicity, and outlines the clinical manifestations of cocaine exposure and toxicity in adult and pediatric populations. We conclude from the available clinical reports that there must be a higher index of suspicion in the pediatric population to identify exposed infants and children. Improved recognition and identification in both typical and atypical populations will result in better characterization of acute cocaine toxicity.

Does ethanol enhance cocaine toxicity?

OBJECTIVES

Results of in vitro and animal studies suggest that ethanol enhances cocaine toxicity. If so, then that this implies that in ethanol users, postmortem blood cocaine concentrations should be lower, or anatomic evidence demonstrable.

METHODS

Drug concentrations and autopsy findings were compared in a sample of 72 accidental deaths, where only cocaine, cocaine metabolites, and ethanol were detected. Findings in ethanol positive (E+) and negative (E-) deaths were compared using multiple Student's t-tests and chi2 testing for categorical variables.

RESULTS

There were 47 E-decedents and 24E+. Mean ages were similar (40.2 +/- 8.7 and 37.5 +/- 11.1 years respectively). Mean E was 0.113 (range 0.030-0.350 g/dL), and less than 0.080 g/dL in 50% of the cases. Concentrations of C and BE were not significantly different in E- and E+ groups (C = 1.40 +/- 3.6 mg/L, and 0.76 +/- 1.93 mg/L respectively, BE = 3.04 +/- 5.36 mg/L and BE 2.09 +/- 3.77 mg/L, P = 0.4621 and 0.4520). Organ weights were pathologically increased in both groups, but not significantly different. Body Mass Index (BMI) was less (23.9 vs 25.5), and heart weight was greater (449 vs 407 g) than predicted. Over half the decedents had demonstrable heart disease, and 11% died of brain haemorrhage, though the rate for both disorders was similar in each group.

CONCLUSIONS

In two-thirds of the cocaine-related deaths studied, no ethanol was detected. When ethanol was present, no differences between the two groups were identified. The findings suggest that acute cocaine toxicity is not enhanced by ethanol cocaine interactions. However, ethanol concentrations were generally low, and it is possible that increased toxicity is apparent when much larger quantities of alcohol have been consumed.

Evidence for injurious effect of cocaethylene in human microvascular endothelial cells

BACKGROUND

Cocaethylene (CE) is a conjugate of cocaine and ethanol that may contribute to the pathogenesis of systemic vascular diseases. This study was conducted to investigate the effect of CE on human microvascular endothelial cells (HMEC-1) in culture.

METHODS

Proliferating and confluent monolayers of HMEC-1 were used for assessing growth kinetics, viability, cytotoxicity, and morphologic/barrier alterations after CE treatment (0-1 mmol/l) for up to 7 days. The Trypan blue exclusion, lactate dehydrogenase (LDH) release assay, manual cell counts, and silver nitrate staining technique were used.

RESULTS

The doubling times of 30.0 and 31.4 h for the 0.5 and 1.0 mmol/l CE-treated HMEC-1, respectively, were significantly longer than the 28.6 h for the control group (p < 0.05). The viabilities of 90.4 +/- 3.8% (control) and 93.1 +/- 1.9% (CE-treated) from the Trypan blue exclusion-staining experiments indicated non-lethality of CE. LDH activities of 173 +/- 33 U/l (control) and 157 +/- 43 U/l (CE-treated) confirmed the absence of CE cytotoxicity. Silver staining results indicated increased monolayer permeability as demonstrated by the formation of intercellular gaps after 1 h of exposure.

CONCLUSIONS

HMEC-1 exposure to CE induced cellular injury that could affect the permeability of small blood vessels. These cellular changes could in part be the pivotal point for studies to explain the edema and inflammation in surrounding tissues of individuals exposed to CE.

Cocaethylene's effects on coronary artery blood flow and cardiac function in a canine model

OBJECTIVES

Cocaethylene is a toxic metabolite of cocaine formed in the presence of ethanol. Though cocaine causes coronary vasoconstriction, cocaethylene's effects on coronaryflow are unknown. The aim of our study was to describe cocaethylene 's effects on coronary flow and cardiac function.

METHODS

Sixteen alpha-chloralose anesthetized dogs were monitored with Swan-Ganz, arterial and venous catheters, and an electrocardiogram. Dopplerflow probes were placed on the circumflex and left anterior descending coronary arteries. Dogs were allotted 15 mg/kg (n = 10) or 30mg/kg (n = 6) of cocaethylene given as a continuous intravenous infusion. Measurements were made at fixed time intervals during the 60-minute cocaethylene infusion and 2-hour observation period.

RESULTS

The cocaethylene concentrations were maximal at the end of the infusion and cocaethylene was rapidly metabolized to benzoylecognine. One low-dose animal died of ventricular fibrillation. Five high-dose dogs experienced ventricular arrhythmias or pulseless electrical activity (PEA), and three died. In the low-dose group, cocaethylene caused a 38% increase in mean arterial pressure relative to baseline, and increased systemic vascular resistance. In the high-dose group, at maximal cocaethylene concentrations, stroke volume decreased by 42% (p < 0.0002), and circumflex blood flow decreased by 30% (p = 0.03) relative to baseline, when arrhythmias occurred. The PR, QRS, and QTc intervals increased by 48, 209, and 29%, respectively (p < 0.001). As cocaethylene levels declined, circumflex blood flow increased by 77% (p = 0.05) and mean arterial pressure increased 49% (p < 0.01), also relative to baseline.

CONCLUSIONS

Cocaethylene caused hypertension and increased systemic vascular resistance. At high concentrations, it decreased myocardial function, slowed cardiac conduction, and was arrhythmogenic. The cocaethylene's toxicity does not appear to be mediated by effects on coronary blood flow.