Levamisole exposure and hematologic indices in cocaine users.

OBJECTIVES: Levamisole is an antihelminthic agent found in nearly 70% of seized U.S. cocaine. Sporadic case literature describes a life-threatening agranulocytosis associated with levamisole exposure secondary to cocaine use. The authors compared the distribution of hematologic indices in a population of cocaine users with and without a confirmed exposure to levamisole.
METHODS: The records of all patients in the Lifespan hospital system who underwent comprehensive toxicologic testing between September 2009 and December 2009 (n = 799) were reviewed. Of these, 95 patients were eligible for inclusion (cocaine-positive with a simultaneous complete blood count). Patients were grouped into levamisole-positive (n = 47) and -negative (n = 48) groups. The primary outcome measures were total white blood cell count (WBC), absolute neutrophil count (ANC), and absolute lymphocyte count (ALC); secondary outcome measures included percent neutrophils, lymphocytes, eosinophils, monocytes, and basophils, as well as identified co-ingestants.
RESULTS: Both groups had a similar makeup of age, sex, and race. The total WBC count, ANC, and ALC were not significantly different between the two groups. There was no significant difference in relative proportion of neutrophils, eosinophils, basophils, or monocytes between the groups. There was one neutropenic patient in the levamisole-positive group, while three patients were neutropenic in the negative group. Additionally, a literature review of case reports describing levamisole-induced agranulocytosis (n = 33) was conducted. In 52% of these cases, patients presented with an oropharyngeal chief complaint; in an additional 27%, patients presented with soft tissue infections or purpura.
CONCLUSIONS: The overall incidence of neutropenia was 4.2% in all cocaine users and 2.1% in the levamisole-positive group. A striking number of the reported patients with levamisole-associated neutropenia have presented to care with oropharyngeal complaints, vasculitis, or fever. A clinical algorithm for identifying levamisole toxicity in the emergency department setting is provided. Further research is necessary to determine the circumstances required for levamisole-associated neutropenia.