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Levamisole Toxicity

      To the Editor:
      The review of levamisole toxicity by Lee et al
      • Lee K.C.
      • Ladizinski B.
      • Federman D.G.
      Complications associated with use of levamisole-contaminated cocaine: an emerging public health challenge.
      published in the June 2012 issue of Mayo Clinic Proceedings does not mention leukoencephalopathy as a well-documented and serious complication of this drug (and cocaine adulterant). Patients may present with a variety of neurologic symptoms related to multifocal white matter lesions that can be identified on magnetic resonance imaging. The lesions do not appear to be vasculitic and are often reversible with cessation of levamisole exposure. In the setting of cocaine abuse, the clinical and magnetic resonance imaging features can be confused with other complications of cocaine abuse and high-risk lifestyles.
      • Kimmel D.W.
      • Wijdicks E.F.
      • Rodriguez M.
      Multifocal inflammatory leukoencephalopathy associated with levamisole therapy.
      • Xu N.
      • Zhou W.
      • Li S.
      • Zhou G.
      • Zhang N.
      • Liang J.
      Clinical and MRI characteristics of levamisole-induced leukoencephalopathy in 16 patients.
      • Graebner R.W.
      Two rare leukoencephalopathies presenting with ataxia.

      References

        • Lee K.C.
        • Ladizinski B.
        • Federman D.G.
        Complications associated with use of levamisole-contaminated cocaine: an emerging public health challenge.
        Mayo Clin Proc. 2012; 87: 581-586
        • Kimmel D.W.
        • Wijdicks E.F.
        • Rodriguez M.
        Multifocal inflammatory leukoencephalopathy associated with levamisole therapy.
        Neurology. 1995; 45: 374-376
        • Xu N.
        • Zhou W.
        • Li S.
        • Zhou G.
        • Zhang N.
        • Liang J.
        Clinical and MRI characteristics of levamisole-induced leukoencephalopathy in 16 patients.
        J Neuroimaging. 2009; 19: 326-331
        • Graebner R.W.
        Two rare leukoencephalopathies presenting with ataxia.
        Wisconsin Neurological Society, Madison, WINovember 11, 1995

      Linked Article

      • Complications Associated With Use of Levamisole-Contaminated Cocaine: An Emerging Public Health Challenge
        Mayo Clinic ProceedingsVol. 87Issue 6
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          Levamisole is an immunomodulatory agent that was used to treat various cancers before being withdrawn from the United States market in 2000 because of adverse effects. Levamisole is currently approved as an antihelminthic agent in veterinary medicine, but is also being used illicitly as a cocaine adulterant. Potential complications associated with use of levamisole-laced cocaine include neutropenia, agranulocytosis, arthralgias, retiform purpura, and skin necrosis. Treatment is primarily supportive, and skin lesions typically resolve with cessation of cocaine use.
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      • In reply
        Mayo Clinic ProceedingsVol. 87Issue 10
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          We appreciate Dr Graebner's comments regarding levamisole-induced leukoencephalopathy, a well-documented complication of levamisole when used in high doses for treatment of conditions such as malignant melanoma or severe recurrent aphthous ulcers.1,2 During the drafting of our manuscript,3 the association between leukoencephalopathy and levamisole-contaminated cocaine had not been reported in the literature. Since then, one article has raised the possibility of multifocal inflammatory leukoencephalopathy resulting from levamisole-adulterated cocaine, suggesting that this complication can also occur with small amounts of levamisole found in cocaine.
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