[Orphan drugs : New opportunities for the treatment of rare diseases].

Not only in Europe and USA, but also in many other countries rare disorders-so-called orphan diseases-have attracted more and more attention. The formation of specialized centers for rare disorders has enabled the diagnosis of diseases that have been widely unknown before. In addition, pharmaceutical companies have recognized orphan diseases as a profitable source of revenue. The development and marketing of new drugs for rare diseases-so-called orphan diseases-means a great challenge for all who participate in the health care system: Because the number of patients who are available for a clinical study is mostly very small, it is often very difficult or even impossible to show statistically firm evidence of efficacy. The standard placebo-controlled, double-blind clinical trial is often inappropriate for the approval procedure of an orphan drug; thus other study designs or other parameters (e.g. biomarkers) have to be used to prove clinical efficacy of the study drug. Only relatively small amounts of drugs can be sold to the generally few patients affected by an orphan disease and clinical trials require an high amount of financial investment; therefore orphan drugs have in general extremely high prices. How long these high expenses can be borne by the health care system in view of the great number of rare diseases remains questionable.