Strychnine is an odorless, white, bitter crystalline powder that can be inhaled, taken orally, or mixed and given intravenously. It is a strong poison that needs only a small amount to produce severe health affects, including death (1).                           

                 







                    Strychnine

Historical Facts About Strychnine:
Strychnine was first discovered in 1818. The unpurified plant extract, nux vomica, from which it is the active component, had been known and used for both medicinal and criminal purposes for some time (2).

   

    The strychnine tree is medium sized with a crooked, thick trunk. The wood is    
    hard and durable and the roots are very bitter. The branches are irregular,    
    covered with a smooth ash-colored bark. The flowers are small and white funnel
    shaped, which bloom in the cold season and have a disagreeable smell. The fruit
    of the nux vomica are about the size of an apple, with a smooth rind, which
    when ripe is an orange color filled with white jelly pulp, containing five seeds.     The seeds have no odor, but are very bitter (3).
   
    In the past strychnine was in a pill form and was used to treat a variety of human
    ailments (1). It is an alkaloid molecule found in seeds of t
    the plant Strychnos Nux Vomica, native to India, Sri    
                                                Lanka, and Australia, and a few related species (2).
         Strychnine Tree
                                                                                                                                
Today, strychnine is used primarily as a pesticide to kill rats. Occasionally, it is mixed with street drugs like LSD, heroin, and cocaine (1).

Medicinal Action and Uses of Strychnine:
The properties of nux vomica are substantially those of the alkaloid Strychnine. The seeds are used in atonic dyspepsia, while the tincture is used in mixtures for its action on the gastro-intestinal tract. The bitter taste increases appetite. It also stimulates peristalsis, in constipation, due to "atony of the bowels." It is often combined with other laxatives for it's good effects (3).
Strychnine, the main alkaloid constituent in the seeds, is also a bitter, which increases the flow of gastric juice. It is quickly absorbed in the intestines, after it exerts its characteristic effects on the central nervous system. Strychnine is slowly excreted and its actions are cumulative in small doses. It is used as a gastric tonic dyspepsia (3).

How Strychnine Works:
Strychnine prevents the proper operation of the chemical that controls nerve signals to the muscles. "The chemical controlling nerve signals works like the body's "off switch" for muscles"(1). When it does not work correctly, muscles throughout the body have extreme, painful spasms. Even though the person's consciousness or thinking are not affected, eventually the muscles tire and the person cannot breathe (1).
The extent of the poisoning caused by the strychnine depends on the amount and route of exposure and the person's condition of health at the time of exposure. The effects of strychnine also differ according to the methods it is administered by. Hypodermic injections are the most active and have the most rapid effects. Dissolving tablets taken under the tongue is next in efficiency. Results are typically seen 15-20 minutes after the drug as been administered (1).

Strychnine Exposure:
There are multiple ways one could be exposed to strychnine. You could be contaminated by drinking water   that has had strychnine released into it. You could also be exposed by eating contaminated foods. You could also be contaminated by inhaling strychnine. It could be absorbed through the membranes in the nose, mouth, or eyes by strychnine being in the air. When mixed with street drugs, it can be snorted or smoked. There have also been cases reported where strychnine was given intravenously (1).

Mechanisms of Action:
In the central nervous system there are two distinct types of receptors. Binding at a stimulatory receptor increases the likelihood of a signal being transmitted, while binding to an inhibitory receptor reduces it.
 Glycine receptors are one of the main types of inhibitory receptors, especially in the lower parts of the central nervous system. When strychnine is introduced into the body, it is these receptors that are blocked. This can cause an over-transmission of signals, resulting in reflex arcs, which are usually suppressed by the post-synaptic action of glycine, becoming active, so that the smallest sensory stimulus produces powerful muscular contractions (2). "It has been shown that the drug decreases the excitability and increases the level of polarization of the dorsal root terminals, but does not change motorneuron excitability to extracellular stimulation. Inhibitory influences can be deleted in this structure after strychnine poisoning" (4).
These contractions can lead to powerful and painful convulsions due to no impairment of cognitive or sensory function. Due to spasms and paralysis of the respiratory muscles, respiratory arrest occurs, resulting in death(2).

Strychnine Effects:
Small dose of Strychnine improve the appetite, due to the bitter taste, and it gives "a strong and hopeful feeling"(5). With a full medicinal dose, the respiration is deepened and quickened, blood pressure and the pulse are also increased. The body temperature typically stays constant, except when poisonous doses are given. Strychnine has the greatest effects on the nervous system where its actions are confined mostly to the centers in the cord and medulla (5). Although, the exact point of it's action along the cord is unknown, there have been multiple attempts in trying to explain the mechanism in which strychnine influences spinal cord activity. There has been a decrease in the size of post-synaptic potentials, but there has been a strong decrease in inhibitory influences from vestibular stimulation occurances in the cord treated with strychnine (4). The brain is somewhat effected. The field of action is extended where simple reflexes may take place (4).
The physical symptoms of a full medicinal dose are slight shuddering, sense of constriction of the fauces and jaws, sudden shock-like pains passing through the limbs, the starting of some voluntary muscles, dilated pupils, paleness, and perspiration. The sense of touch and vision are most affected of the senses. The field of vision is enlarged, especially for the color blue (4).

Signs and Symptoms:
Following the ingestion of strychnine, symptoms of poisoning usually happen within 15-60 minutes. People exposed to low or moderate doses by any route could have (1):
-Agitation
-Ability to be easily startled
-Apprehension/ Fear
-Restlessness
-Painful muscle spasms
-Fever
-Kidney/Liver injury

Treatment:
Strychnine poisoning can be treated with barbiturate sedatives and muscle relaxants by avoiding unnecessary sensory stimulation, if caught in time (2).
With the proper treatments the poison can be eliminated and withdrawn from the body in a few days due to strychnine's relatively short half-life of about ten days (2).
There have been treatments done in strychnine poisoned horses where xylazine was beneficial. Pentobarbital and diazepam were also used in treating the sick horses. Mineral oil and charcoal  also proved to be beneficial in decreasing the amount of strychnine in the ailmentary tract of the horses (6).

"The minimum lethal dose is about 50 to 100 mg for adults after the ingestion"( 7).


References