The Ethical and Practical Issues of Market Exclusivity for Naturally Derived Dermatologic Medications: The Case of Cantharidin.

New dermatologic therapies derived from long-used natural substances can enter the market at prices far above previously available compounded or imported formulations, once they receive United States Food and Drug Administration (FDA) approval. Patent protection is often blamed for this shift, but the mechanism at work, in most cases, is FDA-granted market exclusivity, a distinct incentive that can apply even to substances too old to be patented. Herein, we examine how this incentive structure has affected access to cantharidin, a naturally derived agent long used to treat verrucae and molluscum contagiosum, following its formal FDA approval. We outline the ethical tensions this type of scenario raises for physicians trying to balance beneficence, non-maleficence, autonomy, and justice. Rather than a blanket exception for compounding, targeted evidence-based reforms are proposed that could preserve incentives for genuine innovation while protecting patient access and distributive justice.