Amifampridine (3,4-diaminopyridine phosphate) is approved for Lambert-Eaton syndrome under laws designed to encourage manufacturers to develop drugs for life threatening or chronically debilitating rare disorders—“orphan diseases.”1 2 It costs up to £44 200 (€52 000; $71 300) per patient each year (doi:10.1136/bmj.c6466). When bought from chemical suppliers, the equivalent dose of 3,4-diaminopyridine base costs £280. The clinical evaluation of the product relies on published literature that refers mainly to clinical experience with the free base form of 3,4-diaminopyridine.3 The European Union legislation under which it is licensed allows medicines to be designated “orphan drugs” during development, receive financial benefits before approval, and have several years free from competition if granted a marketing authorisation (licence).

The intention of orphan drug legislation in the United States and Europe—put bluntly—is to make the development of drugs for orphan diseases profitable. The unintended consequence is exploitation of the rules for profit. Like tax avoidance, this is legal, but not necessarily desirable.

The regulations can be …