Why are cocaine and heroin sometimes cut with strychnine or arsenic?

Dear Cecil:

I read that cocaine is cut with strychnine, arsenic, or other substances to stretch the volume for increased profits. I can understand milk sugar in heroin, but why these deadly poisons? Do they accelerate the effect of the drug or what?

Cecil replies:

Dunno, but they sure scare the pants off potential users, which is maybe why strychnine and other poisons figure so prominently in media and for that matter medical reports of the dangers of drugs. Truth is, adulterating cocaine with strychnine or arsenic seems to be rare. The U.S. Drug Enforcement Administration analyzed 2,944 samples of cocaine confiscated in five cities between 1974 and 1980. Adulterants found in at least 5 percent of the samples were reported; strychnine and arsenic didn’t make the cut. Here’s the stuff that did: lactose (milk sugar), 29 percent of samples; lidocaine (local anesthetic), 29 percent; mannitol, 26 percent; inositol, 10 percent; dextrose, 8 percent. (The last three items are all sugars.)

A team of researchers (Shesser et al, 1991) also went through DEA bulletins and the forensic science literature from 1982 through January 1989 looking for reports of contaminants. They found mentions of 48 substances, everything from heroin and amphetamine to baking soda and caffeine — but no strychnine or arsenic. Strychnine and arsenic were found on occasion in heroin, though.

So maybe you want to rephrase the question. Why would you put strychnine or arsenic in heroin? Cecil can but guess. Strychnine in low doses is a stimulant; the seeds of the nux vomica tree, from which it’s derived, were once used to make a medicinal tonic. Heroin is a narcotic, not a stimulant, but maybe dealers figure a drug is a drug and they might as well mix the two together. A more likely explanation, though, is that dealers will cut their wares with any powder that’s cheap, white, and available, and strychnine (commonly used as a rat poison) fills the bill. In a pinch, I suppose, so does arsenic.

The fact that coke isn’t usually cut with rat poison doesn’t mean the stuff it is cut with is harmless. Milk sugar won’t do much to you apart from irritating your nose but the same can’t be said for lidocaine. Lidocaine, benzocaine, procaine, and other local anesthetics are used to stretch cocaine because they can’t readily be distinguished from the real thing when snorted. But if you get too much — and the average street sample of cocaine is only 40 percent pure, leaving a lot of room for chemical surprises — you could suffer tremors, hallucinations, seizures, or in the odd case death. And since the stuff you buy on corners doesn’t have the ingredients printed on the side, you won’t even be sure what from. Let the buyer beware.

Send questions to Cecil via cecil@straightdope.com.

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