What defines 'orphan drugs'?

Orphan drugs are specifically defined as medications developed to treat rare diseases, which are conditions that affect a small percentage of the population. The designation is important because pharmaceuticals targeting these rare conditions often do not generate sufficient financial return on investment for manufacturers, given the small patient population.

The term "orphan" implies that these diseases lack sufficient market interest or financial incentive for the typical pharmaceutical companies to invest in their development, hence they might be "orphaned" by the industry. Regulatory agencies, such as the FDA in the United States, have established incentives for the development of orphan drugs, including tax credits, user fee waivers, and market exclusivity after approval.

In contrast, medications developed for common illnesses typically do not qualify as orphan drugs because they target diseases that affect a larger segment of the population, which makes them more commercially viable. Drugs that are no longer in production are not categorized as orphan drugs; instead, they are considered discontinued due to various reasons, including lack of demand or safety concerns. Over-the-counter medications are also not related to the orphan drug category, as they are available without a prescription and target a broader array of common ailments, rather than specific rare conditions.