Cantharidin, a monoterpene found in certain insect species, has undergone a remarkable transformation. Initially used controversially as an aphrodisiac, it is now an active ingredient against Molluscum contagiosum. In the United States, it has already received approval.
Molluscum contagiosum, commonly known as water warts, are small, centrally indented warts caused by the Molluscum contagiosum virus (Poxvirus mollusci). While most individuals experience spontaneous healing after months, these warts can persist for several years. They can be removed surgically or through cryotherapy or laser therapy. Treatment with 5 percent potassium hydroxide (a medical product) is also an option.
In late July, the US Food and Drug Administration (FDA) approved Ycanth®, a Cantharidin-containing drug developed by Verrica, for the topical treatment of Molluscum contagiosum in adults and children aged two and older. This marks the first FDA-approved drug for Molluscum contagiosum in the United States.
Cantharidin, a perhydrated phthalic anhydride derivative (VP-102), is a toxic monoterpene found in various beetle species. It was named after the Cantharidae family (soft-shelled beetles) or the former genus name of the Spanish fly (Cantharis/Lytta vesicatoria), where it was initially described.
Cantharidin was previously used as a purported aphrodisiac that could induce long-lasting erections in men. It was applied locally or ingested in a dissolved form, often using crushed Spanish fly. It was also used in skin irritant therapy and as a means of wart removal. Due to its strong skin-irritating effect, it was once used in experimental pharmacology in the blister test (Cantharidin test).
Application by trained medical professionals only Ycanth must be applied by trained medical personnel only. It contains a 0.7 percent Cantharidin solution administered via a special disposable applicator. The viscous active substance solution includes two additives: the dye gentian violet allows precise application on the Molluscum contagiosum without affecting the surrounding skin, while the addition of the strong bitter substance denatonium benzoate is meant to prevent (misuse via) oral ingestion. Denatonium benzoate is a benzyl derivative of lidocaine with a quaternary ammonium structure.
Molecular Mechanism of Action
The molecular mechanism of action of Cantharidin is not yet fully understood. It is suspected to degrade desmosomes in virally infected keratinocytes, causing them to detach and facilitate viral clearance. Desmosomes are adhesive structures in cell membranes that create strong connections between two cells. They are particularly present in epithelial cells and contribute to mechanical cohesion.
The approval is based on the results of two identical randomized, double-blind, placebo-controlled Phase III studies (CAMP-1 and CAMP-2) involving patients aged two and older. The primary endpoint was the complete elimination of all treatable Molluscum contagiosum. This was achieved by 46 percent and 54 percent of participants in the Cantharidin group (CAMP-1 and CAMP-2), respectively, compared to 18 percent and 13 percent of participants in the placebo group.
Side effects were mostly mild to moderate. Ninety-seven percent of treated individuals experienced local skin reactions at the application site, such as blistering, itching, pain, discoloration, and erythema. There were no serious adverse effects reported. The discontinuation rate due to an adverse reaction was 2.3 percent in the Cantharidin-treated group and 0.5 percent in the placebo group.
Original source: This information was Initially covered by PZ.de and has been translated for our readers.