Levamisole Found in Patients Using Cocaine

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To the Editor:

It is common practice that illicit drugs such as cocaine and heroin are often mixed (“cut”) with other substances prior to their being sold on the streets. Some of these agents include prescription drugs such as diltiazem, lidocaine, or acetaminophen, or other over-the-counter agents such as baking soda, caffeine, multi-vitamins, or sugar.¹, ² I am writing to alert physicians of the trend that cocaine is being mixed with the medication levamisole. Therefore, when dealing with patients who are actively using illicit substances it is important to remember that unusual reactions to known street drugs may be the result of the cutting agent rather than the direct toxic effects of the illicit substance. Levamisole, originally an anthelmintic medication, now has limited use as a part of a combination treatment in colon cancer. Outside the United States, it still is “primarily used in veterinary medicine to control parasites in livestock.”³ Serious side effects have been reported with the use of levamisole including: “allergic reactions (difficulty breathing; closing of the throat; swelling of the lips, tongue, or face; or hives); decreased bone marrow function or blood problems (fever or chills; or signs of infection); nervous system problems (confusion or loss of consciousness, extreme fatigue, memory loss, muscle weakness, numbness or tingling; seizure, speech disturbances); among others.”⁴ The Drug Enforcement Agency has reported its existence in the US, and several reports have documented the practice of using levamisole as a diluting agent in Europe and other parts of the world.², ⁵ To my knowledge, there have not been any clinical reports of cocaine being cut with the prescription medication levamisole locally. In the New Orleans area, we are seeing patients frequently present to the emergency departments for a variety of medical and psychiatric complaints after recent cocaine use. At times, their symptoms are not totally explained by an underlying medical cause or their recent cocaine intoxication or medical causes, but due to other active medications found in their system. These patients have urine drug screens positive for cocaine or cocaine metabolites, and upon further evaluation with gas chromatography the presence of levamisole is also found. None of these patients had clinical indications for this medication, or had knowledge of its use. It is important to remember that when treating individuals who are using street drugs other agents are commonly mixed into the drugs without their knowledge. With this in mind, unusual signs or symptoms of intoxication may not be solely the result of a known ingestion, but may also be due to the effects of cutting agents.

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References 

1. Ramsey J. Stimulant drug using trends in clubs & pubs: what drugs are on the streets?. http://www.coca.org.uk/uploads/stimulants.pdfAccessed September 23, 2008
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2. Morley SR, Hall CJ, Forrest ARW, et al. Levamisole as a contaminant of illicit cocaine. Journal of the Clandestine Laboratory Investigating Chemists Association. 2006;16:6–11
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3. Lintemoot J. Drugs in the news: levamisole: an unusual finding in a cocaine related fatality. http://www.cal-tox.org/Downloads/Monographs/Levamisole.pdfAccessed September 23, 2008
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4. Health Advisory, Delaware Health Alert Network #102 September 2, 2005. http://www.dhss.delaware.gov/dph/php/alerts/dhan102.htmlAccessed September 23, 2008
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5. Fucci N. Unusual adulterants in cocaine seized on Italian clandestine market. Forensic Science International. 2007;172:2–3e1
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