New Remedies from Old Poisons

Arsenic: Targeting Leukemia

By Susan Freinkel|Monday, July 01, 2002

Botox: Taming Unruly Muscles
    The bacterium Clostridium botulinumproduces a poison so deadly that a few hundredths of an ounce can killa million people. Small wonder it's one of the most dreaded agents ofbiological warfare. Yet it is also one of the most widely usedtherapeutic drugs—at least in the domesticated form known as Botox. Inthis purified version the toxin is delivered in minute doses of a fewtrillionths of an ounce. It would take 70 times that amount to killsomeone. Originally developed for the treatment of uncontrollableblinking, Botox is now used to help treat some 40 ailments, rangingfrom crippling diseases such as cerebral palsy and Parkinson's toless-than-life-threatening troubles like facial wrinkles and excessivesweating. It may even ease migraines for some people. "Besides aspirinand penicillin, there are very few drugs I can think of that have somany uses," says Eric First, a physician who has studied botulinumtoxin for 12 years. "And Botox has fewer side effects." The drug helpsregulate the release of a neurotransmitter called acetylcholine, whichplays a key role in relaying messages from nerves to muscles, as wellas in cognitive function and hormonal production. Too muchacetylcholine can cause painful muscular contractions. In cervicaldystonia, for instance, the neck is frozen at an excruciating angle(remember Ed Sullivan's famous leaning posture?). Injecting Botox intothe affected muscles slows acetylcholine release, allowing them torelax.

Nicotine: Focusing Attention
   Nicotine has potent effects on the brain, which is precisely why it isso addictive. It's known to focus attention and improve working memory;it can calm someone who is anxious and stimulate someone who islistless. The nervous system is studded with nicotinic receptors,neurons that help regulate the release of important neurotransmitterssuch as acetylcholine, serotonin, and dopamine. "Nicotine fine-tunesthe system," says Paul Newhouse, a clinical neuroscientist at theUniversity of Vermont College of Medicine. "It's the perfectpsychotropic drug." As little as one ten-thousandth of an ounce of purenicotine delivered in a single dose could kill you. But two times thatamount delivered through nonaddicting time-release patches causesmodest improvements in the memory and concentration of Alzheimer'spatients, who are typically short on acetylcholine. Nicotine is an evenbigger boon for children with Tourette's syndrome, whose illness isrelated to an excess of dopamine. When Paul Sanberg, a neuroscientistat the University of South Florida College of Medicine, gave youngTouretters nicotine patches, he found that the children suffered fewertics and were less aggressive and depressed. The same treatment seemsto improve focus for children and adults with attention deficithyperactivity disorder. Nicotine may even help keep schizophrenicsanchored to reality and depressives from total despair. Nonetheless,the tendency of nicotine to elevate heart rate and blood pressure andcause nausea worries many physicians. So drugmakers are already workingon copycat compounds with the same beneficial touch but none ofnicotine's bite.

Snail Venom: Relieving Pain
   A lowly cone snail buries itself in the sand, leaving only a brightlycolored, wriggling wormlike appendage visible. When a curious fishmoves in for a nibble, the snail harpoons it with this barbedappendage, injecting venom that causes paralysis in seconds. Aroundeight-hundredths of a fluid ounce of a compound extracted from thevenom produces happier results when injected into the space surroundingthe spinal cord of people with chronic pain, including those who areterminally ill. "It's 100 to 1,000 times more potent than morphine,"says University of Utah psychiatrist and biologist Michael McIntosh,who isolated the compound for a drug, dubbed Ziconotide or Prialt, thatis now awaiting FDA approval. Other researchers have isolated apromising analgesic from the snail venom, as well as a possibleanticonvulsant. Still, one would be well advised to steer clear of livecone snails, which are found in reef environments throughout the world.The natural venom can cause weakness and loss of coordination. Inextreme cases it can even result in respiratory muscle paralysis thatcan be fatal.

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