Cantharides, tincture and all vesicating liquids, preparations or admixtures of.
CANTHARIDES, or Spanish Flies, the common blisterbeetles (Cantharis vesicatoria) of European pharmacy.
Cantharides owe their value to the presence of a peculiar chemical principle, to which the name cantharidin has been given.
The British Pharmacopeia contains a large number of preparations of cantharides, but the only one needing special mention is the tincture, which is meant for internal administration; the small dose is noteworthy, five minims being probably the maximum for safety.
The external action of cantharides or cantharidin is extremely characteristic. When it is applied to the skin there are no obvious consequences for some hours.
When applied in this fashion a certain quantity of the cantharides is absorbed.
Cantharides is used externally for its counter-irritant action.
Several green-coloured beetles are, on account of their colour, used as adulterants to cantharides, but they are very easily detected by examination with the eye, or, if powdered, with the microscope.
Those which act on the skin: The best known of these is cantharides (Spanish fly), the active principle of which is a colourless crystalline body - cantharidin - which is extremely irritating.