Why is cocaine adulterated with an animal dewormer? Mystery solved?

February 20, 2014, 7:41 pm


Aminorex, a metabolic of the cocaine adulterant levamisole, exerts amphetamine like actions at monoamine transporters. Hofmaier T et al. Neurochem Int 2013 Dec 1 [Epub ahead of print]


During the last decade, many shipments of cocaine seized by U.S. drug authorities have been found to be adulterated with levamisole, a veterinary anti-worming medicine. The drug in the past has been used to treat various medical conditions in humans, but was withdrawn from the market because of significant  adverse reactions. Levamisole has also been associated with the occurrence of agranulocytosis and dermal vasculitis in drug users exposed to tainted cocaine.

This laboratory study helps suggest why levamisole is so often used as a cocaine adulterant. The authors point out that levamisole is metabolized to form aminorex, and amphetamine-like drug that had been marketed in Europe as an appetite-suppressant and weight loss drug until it was found to cause vasoconstriction and pulmonary hypertension.

It has been speculated that levamisole and/or aminorex may enhance the effects of cocaine. The authors set out to examine what effects levamisole and aminorex have on neurotransmitter transporters and levels of dopamine, norepinephrine, and serotonin.

Using techniques too detailed to go into here  . . . okay, who am I kidding. Not being a lab person, I found it impossible to follow the methods section, so I’m taking the authors somewhat on their word. However, their results are consistent with previous literature on the subject. They found that levamisole itself produced similar, though relatively weak, effects to those of cocaine, inhibiting reuptake of dopamine and norepinephrine (and, to a lesser extent, serotonin). In contrast, aminorex  strongly inhibited uptake of dopamine and norepinephrine while increasing release of serotonin. This total effect of increasing levels of catecholamines in the synapse may enhance and prolong the effects of cocaine itself.

I wonder what underground chemist first figured this out.

H/T @claudiovidalg
Related posts:

Can levamisole-contaminated cocaine cause pulmonary hypertension?

Cocaine-associated hyponatremia: is levamisole the culprit?

Levamisole-adulterated cocaine: an excellent review

Cocaine, levamisole, and the white blood count 

Dramatic pictures: vasculitis caused by levamisole-contaminated cocaine

Scrotal gangrene after smoking crack

Unusual complication of cocaine abuse

Case reports: neutropenia associated with levamisole-adulterated cocaine

Why is the antihelminthic drug levamisole used to adulterate cocaine?

Cocaine adulterated with levamisole implicated in 21 cases of agranulocytosis




  1. Susan Says:

    Heard a rumor it was discovered in horse racing. Horses on it started testing positive for aminorex, which is banned in racing.

  2. Leon Says:


    Yes. A paper by Barker pointed out that starting in 2004 a large number of urine samples from racehorses started turning positive for aminorex. This initially raised suspicion, since the drug has amphetamine-like effects. Eventually, the dewormer levamisole was found to be the culprit.

  3. Gabriel Says:

    Awesome! Saw a case of this last week, the day after a woman took her first dose of bactrim. We chased/anchored on this for three days until she finally admitted to cocaine. Timely posting and appreciated as always.