A crystalline neutral principle prepared from Santonica.

Characters. - Colourless, flat, rhombic prisms, feebly bitter, fusible and subliming at a moderate heat.

Solubility. - Scarcely soluble in cold water, sparingly in boiling water, but abundantly in chloroform and in boiling rectified spirit; not dissolved by diluted mineral acids.

Reactions. - Sunlight renders it yellow; added to warm alcoholic potash it yields a violet-red colour.

Preparation. - The santonica is boiled with milk of lime, strained and partially evaporated. Hydrochloric acid is added to the hot solution, which is set aside to allow the santonin to subside and to separate from oily matter, which is removed by skimming. The precipitate is washed with water and ammonia and purified by boiling in spirit with a little animal charcoal, which is separated by filtering. On the liquid cooling, crystals of santonin are deposited. It is to be protected from light.

Dose. - 1-3 gr. for a child; 2-6 gr. or more for an adult.

Preparations.

B.P.

Dose.

Trochisci Santonini (one grain in each)..........................................

1-6 lozenges,

U.S.P.

Sodii Santoninas (p. 629) .......................................

8-10 gr.

Trochisci Sodii Santoninatis...................................

1-8 troches.

Physiological Action. - Large doses of santonin given to a frog cause paralysis of the cerebrum with abolition of voluntary movement, followed by stimulation of the medulla causing convulsions, which cease on section of the cord. In man, large doses cause headache, giddiness, vomiting, and sometimes death by convulsions, with a tendency to paralysis of the respiration between the convulsions; hence in a case of poisoning treat with chloroform to lessen the convulsions, and keep up artificial respiration.

It produces a peculiar disturbance of vision, so that at first everything appears of bluish and afterwards yellowish or greenish-yellow. The blue appearance lasts only a short time, the yellow vision lasts much longer. This condition is usually regarded as due to stimulation, and subsequent paralysis, of those fibres of the retina by which blue light is perceived. It is eliminated as a sodium salt in the urine and colours it bright yellow; if the urine is rendered alkaline it becomes blood red; these colours are probably due to some product of the oxidation of santonin. The quantity of urine is increased and the patient has a constant desire to micturate; in children it may give rise to incontinence of urine.

Uses. - It is used almost entirely as a vermicide for roundworms in doses of 2-5 gr. every other night, followed by a purgative. It should be given three or four times. It is useless against tape-worms. It has been frequently used as an injection against thread-worms (2-5 gr. in 1 oz. of castor oil).

The best method of administration probably is to give it in castor oil, although not unfrequently it is given in powder for two or three nights running, the last powder being followed by a dose of castor oil next morning. It is best given at bedtime, as the effect on the sight passes off to a great extent during the night.