What makes an orphan drug?

Loopholes in legislation designed to provide treatments for rare diseases are being exploited by drug companies to generate huge returns for very little effort, British doctors have claimed.

In an open letter to the prime minister, 20 consultants and a patient group say that National Health Service patients are being denied access to a potentially life saving treatment since it was licensed under the European Union orphan drug legislation and its price increased by a factor of 40.

Little research was required of the US company BioMarin before it was awarded a European licence for amifampridine (Firdapse), a slightly modified version of 3,4-diaminopyridine, which is unlicensed but has been used for more than 20 years to treat two rare diseases, Lambert Eaton myasthenic syndrome (LEMS) and congenital myasthenic syndrome.

The licence granted for amifampridine covers only the first of these conditions, an autoimmune disease that causes muscle weakness that affects only about 150 patients in the UK at any one time. But the Medicines and Healthcare Products Regulatory Agency (MHRA) has told neurologists that now the drug is licensed they are obliged to use it for both LEMS and congenital myasthenic syndrome, an inherited condition with similar symptoms.

The rules allowed the company to rely on existing evidence of efficacy to gain a 10 year exclusive licence to market the drug. Treating a patient for a year with diaminopyridine costs £800-£1000 (€940-€1200; $1300-$1600) compared with £40 000-£70 000 for amifampridine, depending on dose. Some primary care trusts have refused to fund the drug because they argue that at this price it is not cost effective. In others that do fund it, the high cost is likely to have a knock-on effect, …