This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
Cantharides is the basis of many preparations the object of which is to stimulate the growth of hair, such as the following: Acetum cantharidis B. P., cantharides, 1; glacial acetic acid, 5; water, 1; glycerin, 1; spiritus rosmarini, 1; water, 10. Cantharides is very largely employed to raise a blister, and it is of all drugs the most commonly used counter-irritant. It is applied to the chest in pleurisy, over the pericardium in pericarditis, over the inflamed nerves in neuritis, over the mastoid process in disease of the ear, over joints with chronic effusion into them, over the stomach when there is gastric pain, vomiting, etc. A blister applied over the nerve will often relieve pain in neuralgia. If a further counter-irritant effect is desired, the blister, which is usually pricked, may be irritated by the application of any irritating ointment. Unguentum Sabinae; savine, 8; yellow wax, 3; benzoinated lard, 16; was formerly much used for this purpose. This, however, is very painful, and nowadays after the pricking some bland ointment is usually applied. The cantharides preparation should not be left on after the development of the bleb, lest the cantharidin should be absorbed Cantharides should not be applied to a part on which the patient lies, for a bed-sore may form; nor must it be used in renal disease; and it should be carefully employed in children or debilitated persons. It ought not to be applied to paralyzed limbs. The cuticle raised by a blister may be used for skin-grafting.
The drug is rarely given internally, but it has been used with success in small doses in cases of chronic gleet. Sometimes, but not often, it relieves chordee. Small doses are sometimes useful in the late stage of acute desquamative nephritis. It has been recommended for diabetes insipidus. Cantharidin, in the form of potassium cantharidinate (1/100 gr.; . 0006 gm. hypodermatically ) has been used as a remedy for pulmonary tuberculosis, and for lupus. For all that cures of both of these diseases have been claimed, the value of this drug is by no means established.
In severe cases of poisoning there may be greatly increased sexual desire, numerous seminal emissions, violent priapism, with swelling and heat of the genital organs. In women cantharides may cause abortion or induce menstruation.
Intense gastro-intestinal inflammation is present, consequently swelling, ecchymoses, and hpyeraemia of the mucous membrane of the alimentary canal are observed. The kidneys are found to be very congested, and in the early stage of acute nephritis. There is also much inflammation of the genito-urinary mucous membrane.
There is no chemical nor physiological antidote to Cantharides. The stomach should be emptied by emetics (see p. 139), or washed out by the stomach-pump. Mucilaginous and demulcent liquids should be freely given. Opium is indicated to relieve the pain and gastro-enteritis.