Cocaine contaminated with livestock de-worming drug causes painful purpura

University of Rochester Medical CenterJun 24 2011

Physicians see looming public health problem with levamisole, approved to treat worm infestations in livestock

If the obvious reasons for avoiding recreational drug use aren't off-putting enough, physicians have yet another detrimental consequence to add to the list - crusty, purplish areas of dead skin that are extremely painful and can open the door to nasty infections.

The condition is called purpura. Typical causes include a range of rare disorders, but it is also associated with the use of cocaine. Not just any cocaine, though: Physicians, researchers and health officials believe cocaine contaminated with a de-worming drug commonly used by veterinarians is the culprit. The drug, called levamisole, was found in 30 percent of confiscated cocaine in 2008 and 70 percent in 2009, according to the U.S. Drug Enforcement Administration.

In the Journal of the American Academy of Dermatology, physicians highlight six new and very similar patient cases of purpura, mostly on and around the ears, following cocaine use. The cases - four seen in Rochester, N.Y., and two in Los Angeles - closely resemble two additional cases in San Francisco that were reported previously in the journal. In each case an extensive battery of blood tests ruled out the usual causes of purpura.

The cases were reported by the University of Rochester Medical Center and the University of California, Los Angeles.

Because testing for traces of levamisole in the blood is complex and unreliable, researchers cannot say for sure that it is the direct cause of purpura in these instances. But, due to the striking similarity of these cases, and the presence of another condition caused by levamisole called agranulocytosis - low blood counts that up the risk of infection - in the majority of the patients, doctors say there is strong reason to suspect the drug and to focus greater attention on what could become a widespread health concern.

"We believe these cases of skin reactions and illnesses linked to contaminated cocaine are just the tip of the iceberg in a looming public health problem posed by levamisole," said the study authors.

According to Mary Gail Mercurio, M.D., an author and associate professor in the Department of Dermatology at the University of Rochester Medical Center, "When we first started seeing these patients they all had a similar clinical picture, but they were really an enigma because they weren't falling into any other pattern we'd seen before. When a colleague at the National Institutes of Health mentioned levamisole contamination, we did toxicity screens and lo-and-behold, all the patients came up positive for cocaine. We had our diagnosis."

Drug enforcement officials have detected levamisole - which was once used to treat colon cancer - in cocaine since 2003, but have watched it increase rapidly in recent years. The Drug Enforcement Administration says that the drug, which is inexpensive, is used more and more as a diluting agent in order to stretch supplies. Study authors report that levamisole is known to increase dopamine, a neurotransmitter that helps control the brain's reward and pleasure centers, causing experts to believe it is added to cocaine to further enhance or prolong the user's high, as well.

Researchers don't know how levamisole causes purpura, which occurs when vessels become plugged and blood can't flow to the skin, leading to skin death and the resulting purplish, crusty appearance. Cocaine alone constricts blood vessels, which is probably the first step, but how levamisole contributes is not yet understood, Mercurio said.

Both smoking and snorting tainted cocaine can lead to purpura and both men and women can be affected. Treatment options include steroids to prevent inflammation, but stopping the exposure to cocaine is the best medicine: Mercurio and the other study authors observed that once patients stopped using cocaine, the purpura and low blood counts improved.

"We've seen a lot of cases in Rochester alone, so it is important to alert the gatekeepers of medicine, the primary care physicians who are in the trenches every day, of this diagnosis," said Mercurio. "This is one of those entities that with familiarity and recognition can go a long way in helping physicians to quickly make a diagnosis and intervene without embarking on an elaborate workup where nothing will pan out."