Santonin

Santonin, $C\_\{15\}H\_\{18\}O\_3$, is a crystalline neutral principle extracted from Santonica, the latter being defined in the British Pharmacopoeia as the dried unexpanded flower-heads or capitula of Artemisia maritima, var. Stechmanniana. The plant grows in Russia, and belongs to the natural order Compositæ. Santonin occurs in brilliant white flat crystals, which become yellow on exposure to light, few specimens being colourless unless they have been recently prepared or very carefully kept in the dark. It is odourless, and almost tasteless; practically insoluble in water. Santonin is used in medicine solely as an anthelmintic, and is especially poisonous to the round worm (Ascaris lumbricoides), being much less so to the thread-worm (Oxyuris vermicularis). The dose is 2 to 6 grains for an adult, and 1 to 4 grains for a child; it may be given in powder, alone or mixed with sugar, or dissolved in a little olive or castor oil, or as the officinal lozenge (1 grain in each). It should be used with caution in weakly children. It is excreted in the urine, to which it imparts a deeper yellow colour, changing to red if the urine become alkaline. On colour vision it has often a peculiar effect, the cause of which has never been satisfactorily determined. Objects appear first purple or blue and then yellow, colour vision becoming finally destroyed.