Evaluation of two enzyme immunoassays for the detection of the cocaine metabolite benzoylecgonine in 1,398 urine specimens

False-Positive Serum Cocaine Screening Results in Patients Undergoing Evaluation for Renal Transplant

Drug screening during pre-transplant evaluations can have major implications for patient care, particularly because drug abuse has been associated with poor transplant outcomes. Although urine drug screening is usually preferred, serum testing is available for situations such as anuria due to end stage renal disease. However, there are few studies evaluating serum drug screening in specific populations such as patients undergoing kidney transplant evaluation. All serum drug screens ordered between January 2015 and November 2017 on patients being evaluated for renal transplant were compared against a large population of serum drug screens ordered from other institutions. Cocaine screening and confirmation results were evaluated to determine false positives. Cocaine screens were positive in 23 of 537 (4.3%) pre-transplant samples, and 211 of 5,115 (4.1%) comparison samples. Confirmation testing demonstrated that 14 (60.9%) pre-transplant samples were false positives, which was significantly (P < 0.01) higher than the rate of false positives in the comparison group (47/211, 22.3%). No common medication or other cross-reacting substance could be identified in the pre-transplant cohort to explain the false-positive results. Although serum cocaine screening had a low overall false-positive rate, the proportion of false positives was significantly higher in pre-transplant patients. Given the poor transplant outcomes associated with drug abuse, failure to properly interpret screening results as being false positives could negatively affect patient care. All members of the transplant team should recognize the importance of confirmation testing in this setting, to avoid unintended consequences due to false-positive screening results.

A Practical Guide to Urine Drug Monitoring

Urine drug monitoring is an important tool for substance misuse or abuse and adherence to a prescribed regimen.

Presumptive cocaine toxicosis in 19 dogs: 2004-2012

OBJECTIVE

To characterize the incidence, signalment, presenting complaint, history, clinical signs, diagnostic test results, complications, treatment, length of hospitalization, and outcome of dogs presenting with presumptive cocaine toxicosis.

DESIGN

Retrospective study from March 1, 2004 to March 1, 2012.

SETTING

Twenty-four hour urban university veterinary teaching hospital.

ANIMALS

Nineteen dogs presenting with clinical signs consistent with cocaine toxicosis and having a positive urine cocaine test.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All dogs had neurological abnormalities including bilateral mydriasis (11/19 [58%]), hyperexcitability/hyperesthesia (10/19 [53%]), ataxia (8/19 [42%]), focal or generalized muscle tremors (8/19 [42%]), reduced mental awareness (6/19 [32%]), and seizures (3/19 [16%]). Other signs included weakness (7/19 [37%]), vomiting (6/19 [32%]), and lethargy (3/19 [16%]). Tachycardia was apparent in 10/19 (53%) dogs, hypertension in 4/19 (21%), and hyperthermia in 5/19 (26%). Sinus tachycardia was the only reported cardiac arrhythmia. Bloodwork findings included hyperglycemia in 4/19 (21%) dogs, and increased plasma lactate concentration in 9/19 (47%). Most dogs (16/19 [84%]) were hospitalized for supportive care, which generally included isotonic crystalloid fluid administration, and treatment with sedative or anxiolytic drugs including diazepam, midazolam, acepromazine, and chlorpromazine. Two dogs required further anticonvulsant therapy (phenobarbital and propofol) and 1 dog was treated with a constant rate infusion of esmolol. All dogs survived to discharge, and the median length of hospitalization was 15 hours (10-30 h).

CONCLUSIONS

Cocaine toxicosis was infrequently suspected. Neurological signs predominated, but cardiovascular alterations were also frequently reported. Hospitalization for monitoring and supportive care is recommended given the potential for life-threatening complications such as seizures, hypertensive crisis, and tachyarrhythmias. The prognosis for survival to hospital discharge can be good with the appropriate supportive care.