Strychnine

Molecular formula: C₂₁H₂₂N₂O₂

RMM: 334.40

Molecular Composition: C 75.42%, H  6.63%, N 8.38%, O  9.57%

Properties

Strychnine is an alkaloid obtained from the seeds of Strychnos or Loganiaceae:  Strychnos nux vomica Linnaeus Strychnos ignatii.  It is a colourless, crystalline powder and it has a bitter, metallic taste when dissolved in water, however it is odourless.

Toxic actions

Strychnine is rapidly absorbed from the gastrointestinal tract (mainly from the intestine), nasal passages, or from injection sites and attacks the central nervous system.  Effects usually begin within 15 to 30 minutes.  Occasionally there is a delay of 1 hour if it is taken by mouth, as the time of action depends on whether the stomach is empty or full, and on the type of food that is eaten.  Once the effects start they are as follows:

1.    Increases reflex irritability of the brain and spinal chord.

2.    After large doses the slightest stimulus, especially acoustic, optical, or tactile can cause powerful reflexes.

3.    Convulsions may occur after each stimulus.

4.    Very large doses can cause curare like paralysis of the ends of the motor nerves.

5.    Diminishes the motile power of leucocytes and then stops their motion.

Symptoms

Symptoms start after about 15 – 30 minutes after taking a lethal dose and have the following symptoms:

1.    Initial symptoms are tightness and twitching of the muscles, agitation and hyperreflexia.

2.    Stiffness of the body.

3.    Lockjaw.

4.    Frothing of the mouth.

5.    Cessation of respiration.

6.    Tetanus like attacks appear every 10 – 15 minutes.  During these attacks the eye balls protrude and the pupils enlarge.

7.    Severe cyanosis, which disappears after the attack subsides.

8.    The attacks (each lasting about 3 – 4 minutes) appear to be spontaneous while other times they are the result of external stimuli i.e. noises, slight movements or flashes of light.  The patient never loses consciousness.

9.    When the poisoning is left untreated each attack lasts longer than the previous and the interval between them grows shorter.

10.Up to 10 attacks occur before death or recovery.  This could happen from 10 minutes to 3 hours and is a result of asphyxiation or inner tissue paralysis.

Lethal dose

The lethal dose for adults vary.  The minimal oral lethal dose ranges from 30 to 120 mg, but this is some what lower when given intravenously or subcutaneously.  However, enzymes of hepatic microsomes readily metabolise strychnine.  It is metabolised in such away that 2 lethal doses can be given over 24 hours and not have cumulative effects.