Blood Cocaine and Metabolite Concentrations, Clinical Findings, and Outcome of Patients Presenting to an ED KARI BLAHO, PHD,* BARRY LOGAN, PHD,² STEPHEN WINBERY, P HD, MD,* LYNDA PARK, MD,* AND EUGENE SCHWILKE, BS² The purpose was to determine if blood cocaine or metabolite concentra- tions would accurately reflect the severity of clinical findings in patients presenting to the emergency department, identifying those requiring therapeutic intervention or those at risk for poor outcome. Blood for determination of cocaine and metabolite concentrations was drawn from patients and were determined by an extractive alkylation/mass spectrom- etry procedure. The mean blood concentrations (mg/L) in 111 patients were as follows: cocaine, 0.26  0.5; ecgonine 0.42  0.47; ecgonine methyl ester 0.21  0.37, norcocaine 0.03  0.17; benzoylecgonine 1.28  1.29, cocaethylene 0.02  0.06. Two patients died, 23 required hospital admission, and 88 were discharged from the ED. There was no statistical correlation between cocaine or any metabolite concentration and the severity of clinical symptoms, disposition, need for treatment or out- come. Blood cocaine and metabolite concentrations should be inter- preted with caution because they vary widely and do not predict the severity of clinical findings, the incidence of adverse effects, outcome, or need for interventional therapy. (Am J Emerg Med 2000;18:593-598. Copyright  2000 by W.B. Saunders Company) Little is known about the dose-response relationship for cocaine toxicity in drug abusing patients. Much of the concentration data has been derived from post mortem sampling from cocaine deaths or deaths where cocaine was an incidental finding. Even in the post mortem literature, there is no clear concentration of cocaine that has been linked to toxicity or death, making interpretation of cocaine concentrations difficult. 1-5 Available human data are limited to small amounts of cocaine administered in a controlled experimental setting. Ethical concerns prohibit the adminis- tration of larger or more frequent amounts that might better mimic actual drug abuse practices. Although these types of controlled trials provide valuable information, it is difficult to determine how well these data reflect the cocaine concentrations achieved by the drug abusing population. Individual patient variations, multiple routes of administra- tion, duration of use, coadministration of other drugs, underlying heath and age, could alter the concentration- response parameters to cocaine. It was our initial hypothesis that the severity of symptoms in patients presenting to the emergency department (ED) would correlate with either blood cocaine or metabolite concentrations. Therefore, we surmised that patients with the highest blood concentrations would be the most likely to have or to develop serious cocaine related illness. In this context, cocaine concentrations would be of value in predict- ing patients that would require aggressive therapeutic inter- vention and hospital admission, even if they were relatively asymptomatic on presentation to the ED. METHODS This study was approved by the institutional review board of the University of Tennessee College of Medicine. Con- sent was obtained from all patients before they were entered onto the study and patient confidentiality was strictly maintained. Study Subjects Patients eligible for inclusion were those 18 years of age or older who presented to the ED with suspected or confirmed cocaine use, independent of their chief complaint. There was a general selection bias for symptomatic patients due to the presence of clinical findings that would lead the enrolling physician to suspect cocaine use and that most cocaine abusers do not present for treatment. All data were collected prospectively. After the initial evaluation by one of the investigators, 10 mL of blood was drawn as part of the standard emergency care and placed in a vaccutainer tubes containing sodium fluoride plus potassium oxalate and frozen immediately. To determine any correlation between blood concentra- tions and clinical effects, an objective scale to quantitate the severity of clinical findings was developed (Stimulant Intoxication Scale or SIS) based on the three major systems affected by cocaine. These include the central nervous system (CNS), cardiovascular (CV) and temperature param- eters (Table 1). This scale has similar components used in other assessment scales such as those for alcohol with- drawal. 6-8 To our knowledge, these have not been applied to patients presenting for acute care with sequalae from cocaine abuse. Mild cocaine intoxication was defined by a score of 0-6, moderate by a score of 7-15, and severe intoxication by a score of greater than 15. Scores were From the *Department of Emergency Medicine and Clinical Toxicol- ogy, UT Medical Group; and ²Washington State Toxicology Labora- tory, University of Washington, Seattle, WA. Presented at the Society of Forensic Toxicologists, October 1998. Manuscript received December 7, 1999, returned December 14, 1999, revision received January 13, 2000, accepted February 4, 2000. Address reprint requests to Kari Blaho, PhD, Research Director, Assistant Professor of Medicine and Pharmacology, Department of Emergency Medicine and Clinical Toxicology, 842 Jefferson Ave, Suite A645, Memphis, TN 38103. E-mail: kblaho@ aol.com Key Words: Blood cocaine concentrations, cocaine toxicity, drug abuse, cocaine metabolites. Copyright  2000 by W.B. Saunders Company 0735-6757/00/1805-0005$10.00/0 doi:10.1053/ajem.2000.9282 593