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Full text of "Medical Jurisprudence And Toxicology"

PHYSOSTIGMATIS  SEMINA                                             707

he failed to detect it in a case in which there was ample evidence that death
occurred from poisoning by strychnine.

PHYSOSTIGMATIS SEMINA   (CALABAR BEAN)

This is the dried ripe seed of Physostigma (Venenosum, belonging to N.O. Legu-
minosse. It is known as the Ordeal Bean of West Africa, as it is used there as a test in
suspected witchcraft. It is blackish-brown in colour, and slightly kidney-shaped, having
a black groove along its convex border, measures li"x5"X a", and weighs about 1| to
2 drachms. It has no odour, nor has it any distinctive taste. If cut longitudinally, it is
seen to consist of a brown, rind, containing two hard, white, brittle cotyledons which
adhere to the shell.

The poisonous properties are due to two alkaloids, physostigmine or eserine and
calabarine, contained in the cotyledons of the seed.

Physostigmine (Eserine), CicHaiNaO*.—In the pure state this is a white, crystalline
substance, but becomes yellowish on exposure to air and light. It is bitter in taste and
alkaline in reaction. It is slightly soluble in water, but readily dissolves in alcohol,
chloroform and ether. With acids it forms salts, which are soluble in water. Of these
physostigminaz salicylas (physostigmine or eserine salicylate) is a pharmacopoeial pre-
paration, the dose being 1/100 to 1/50 gram. It enters into the composition of the phar-
macopoeial preparations of Lamelice physostigmince, Oculentum physostigminoe and
Injectio physostigmince salicylatis.

Symptoms.—These are giddiness, salivation, thirst, violent peristalsis, pain in the
stomach, vomiting, sometimes diarrhoea, slow, feeble and irregular pulse, laboured
breathing, cold clammy skin, contracted pupils, muscular twitchings, paralysis of the
voluntary muscles, mystagmus and dysarthria. The intellect remains clear to the last.
Death occurs from asphyxia due to paralysis of the respiratory centre.

Fatal Dose and Fatal Period.—Not determined. Six seeds of beans of Physostigma
venenosum caused the death of a child. According to Blyth 6 mg. of physostigmine
would be likely to be dangerous and about 205 mg. or 3 grains would be much beyond
the least fatal dose.ls A patient was given after an operation for hernia 0.1 gramme of
eserine sulphate (a non-official preparation, dose being 1/64 to 1/32 grain) to stimulate
peristalsis, but he got convulsions and cyanosis and died from failure of respiration and
of the heart's action.10 A case20 is recorded in which recovery took place after intra-
venous injection of J grain of eserine sulphate in 15 minims of water.

Treatment—Give emetics or wash out the stomach with charcoal and tannic acid.
Atropine and chloral hydrate are both regarded as physiological antidotes. Give sti-
mulants, and oxygen inhalation and artificial respiration may be resorted to, if necessary.
Post-mortem Appearances.—Not characteristic. The mucous membrane of the
stomach may be red and congested and may sometimes be covered with a tenacious
mucus, The lungs are generally congested and oadematous. The brain is slightly
hypersemic.

Chemical Analysis.—Physostigmine may be extracted from organic matter by
rendering it alkaline with sodium bicarbonate and using ether or chloroform as a sol-
vent. It is decomposed very easily; hence special care must be taken not to allow
excess of mineral acids, heat or light to come into play.

Tests.—1. Bromine water produces a red or orange-coloured turbid solution which
will clear away on heating. Strong chlorine water produces a red colour.

2. On exposure to air and light, an aqueous solution of physostigmine is readily
oxidized and produces rubreserine, which is red in colour. The red colour is decolourised
on the addition of a reducing agent, such as sulphurous acid or hydrogen sulphide. If it
is now shaken with excess of caustic alkali, it acquires a pink red colour. The red
colouring matter, rubreserine, is dissolved out by chloroform and colours the solution
orange-red.

3. Two or three drops of a very weak solution of physostigmine dropped into a
cat's eye will produce contraction of the pupil.

Medico-Legal Points.—Accidental cases of poisoning have occurred among children
from eating the seeds. Accidental poisoning has also resulted from an overdose in medi-
cine or from eserine solution having been instilled into the eyes or sprayed into the
nose.

Suicidal cases have occurred, but no homicidal case has yet been recorded.

Physostigmine increases the irritability of the voluntary and involuntary muscles,

causing muscular twitchings and peristaltic movements of the intestines.   It contracts

the pupils by stimulating the ends of the third nerve.   It increases the secretions by

stimulating the peripheral nerve endings.   It augments the irritability of the peripheral

18.    Poisons, their Efects and Detection, Ed. V, pp. 422, 423.

19.    Ars. Medici, Jan. 1932, p. 14.

20.    Slater, Brit. Med. Jour,, Dec. 9, 1922, p. 1120.