Emplastrum picis cantharidatum, also known as cantharides plaster, is a medicinal preparation found in ancient pharmacology used externally for its therapeutic properties. This term originates from Latin, with "emplastrum" meaning "plaster," "picis" referring to "tar," and "cantharidatum" signifying "derived from cantharides."
Cantharides, a substance extracted from blister beetles, specifically the Spanish fly (Lytta vesicatoria), is a key component of this preparation. The beetles contain a chemical compound known as cantharidin, which possesses potent vesicant or blistering properties.
Emplastrum picis cantharidatum comes in the form of a plaster or adhesive preparation, typically composed of cantharides mixed with other ingredients, such as resinous substances, tar, wax, and sometimes medicinal herbs.
When applied topically to the skin, the plaster aims to induce a blistering effect as cantharidin penetrates the epidermal layers, leading to irritation and inflammation. This mechanism of action is employed in the treatment of certain medical conditions, such as chronic joint pain, arthritis, and rheumatism. The blistering effect of the plaster is believed to help alleviate symptoms by drawing out toxins, increasing blood circulation, and promoting tissue healing.
However, it is crucial to note that the use of emplastrum picis cantharidatum carries inherent risks. Cantharidin is a highly toxic substance, and excessive application or absorption can lead to severe systemic side effects, including kidney damage. Thus, caution and medical supervision are necessary when utilizing this preparation. Nowadays, alternative, safer treatments are more commonly employed to address
