The drugs used to treat rare diseases are called “orphan drugs”. There are limited numbers of patients available for enrolment in clinical trials, so it is difficult to ascertain the safety and effectiveness of the product being tested for use. It is important that the risk/ benefit ratio is carefully weighed, and that trials be designed to systematically observe patients and attempt to collect adequate data to demonstrate effectiveness, as well as to determine the optimal dosage. Balamuralidhara V. and his colleagues at JSS College of Pharmacy focus on rare diseases and their ethical considerations in clinical development.
https://international-pharma.com/wp-content/uploads/2016/01/Rrae-deseases.pdf