Strychnine

Strychnine (pronounced (British, U.S.),  or  (U.S.)) is a very toxic (LD50 = 10 mg approx.), colorless crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as rodents. Strychnine causes muscular convulsions and eventually death through asphyxia or sheer exhaustion. The most common source is from the seeds of the Strychnos nux vomica tree. Strychnine is one of the most bitter substances known. Its taste is detectable in concentrations as low as 1 ppm.

Strychnine acts as a blocker or antagonist at the inhibitory or strychnine-sensitive glycine receptor (GlyR), a ligand-gated chloride channel in the spinal cord and the brain.

Strychnine poisoning in humans
Strychnine poisoning can be fatal to humans and can be introduced to the body by inhalation, swallowing or absorption through eyes or mouth. It produces some of the most dramatic and painful symptoms of any known toxic reaction. For this reason, strychnine poisoning is often used in literature and film.

Ten to twenty minutes after exposure, the body's muscles begin to spasm, starting with the head and neck. The spasms then spread to every muscle in the body, with nearly continuous convulsions, and get worse at the slightest stimulus. The convulsions progress, increasing in intensity and frequency until the backbone arches continually. Death comes from asphyxiation caused by paralysis of the neural pathways that control breathing, or by exhaustion from the convulsions. The subject will die within 2–3 hours after exposure. At the point of death, the body "freezes" immediately, even in the middle of a convulsion, resulting in instantaneous rigor mortis.

There is no specific antidote for strychnine. Treatment of strychnine poisoning involves an oral application of an activated charcoal infusion which serves to absorb any poison within the digestive tract that has not yet been absorbed into the blood. Anticonvulsants such as phenobarbital or diazepam are administered to control convulsions, along with muscle relaxants such as dantrolene to combat muscle rigidity. If the patient survives past 24 hours, recovery is probable.

Small doses of strychnine were once used in medications as a stimulant, a laxative and as a treatment for other stomach ailments. Strychnine has stimulant effects at low doses but because of its high toxicity and tendency to cause convulsions the use of strychnine in medicine was eventually abandoned once safer alternatives became available.

The dosage for medical use was cited as between "1/60th grain–1/10th grain", which is between 1.1 milligrams and 6.4 milligrams in modern measures. Normally the maximum dosage used was 3.2 mg, half of a "full dose". A lethal dose was cited as 1/2 a grain (32 mg), but people have been known to die from as little as 5 mg of strychnine.

The treatment for strychnine poisoning in the late 19th and early 20th centuries was to administer tannic acid which precipitates the strychnine as an insoluble tannate salt, and then to anaesthetise the patient with chloroform until the effects of the strychnine had worn off.

Strychnine poisoning in animals
Strychnine poisoning in animals occurs usually from ingestion of baits designed for use against rodents (especially gophers and moles) and coyotes. Rodent baits are commonly available over-the-counter, but coyote baits are illegal in the United States. However, since 1990 in the United States most baits containing strychnine have been replaced with zinc phosphide baits. The most common domestic animal to be affected is the dog, either through accidental ingestion or intentional poisoning. An approximate lethal dose for a dog is 0.75 mg per kg body weight. For a 0.3% strychnine bait, five grams of bait could be enough to kill a 20 kilogram dog.

The onset of symptoms is 10 to 120 minutes after ingestion. Symptoms include seizures, a "sawhorse" stance, and opisthotonus (rigid extension of all four limbs). Death is usually secondary to respiratory paralysis. Treatment is by detoxification using activated charcoal, pentobarbital for the symptoms, and artificial respiration for apnea.

Strychnine in drugs
There is a common but false urban legend that strychnine is added to drugs like LSD or that strychnine is present in the peyote cactus. The dose of LSD is so small that it could not be mixed with a toxic amount of strychnine, even if strychnine made up an entire blotter square. See: [http://www.erowid.org/chemicals/lsd/lsd_myth5.shtml Strychnine in LSD? (Erowid)]

Rolling Stones guitarist Keith Richards claims that his worst experience with drugs was when someone put strychnine in his dope. "It was in Switzerland. I was totally comatose but I was totally awake. I could listen to everyone, and they were like, 'He's dead, he's dead!', waving their fingers and pushing me about, and I was thinking, 'I'm not dead!'," he recalled.

Notable strychnine poisonings

 * In the 1904 Olympics, Thomas Hicks (U.S.) won the marathon at St. Louis and collapsed. It took hours to revive him; he had taken brandy mixed with strychnine to help him win his gold medal.
 * Was the first of many poisons used by Agatha Christie to dispatch her victims in her debut novel The Mysterious Affair at Styles in 1921.
 * Used by Norman Bates in Psycho to kill his mother and her lover.
 * A tonic laced with arsenic and strychnine that was religiously given to legendary racehorse Phar Lap may have caused his death.
 * Strychnine was used in several of the murders committed by serial killer Thomas Neill Cream, who poisoned prostitutes on the streets of London.
 * Famous Delta Blues legend Robert Johnson's whiskey bottle was laced with strychnine, resulting in pneumonia.
 * One of Vincent Van Gogh's wives, Margot Begemann, attempted suicide by ingestion of strychnine.