drug orphan drug PMID:22747423 PMID:21682893 PMID:22814660 orphan drugs PMID:21947805 Any drug that has been developed specifically for treatment of a rare medical condition, the condition itself being known as an orphan disease. PMID:23013790 PMID:21180460 PMID:22989856 PMID:22363762 PMID:22731105 PMID:20800761 PMID:23109143 Wikipedia:Orphan_drug chebi_ontology PMID:22371464 PMID:22973866 CHEBI:71031 PMID:22814659 PMID:22739138 PMID:23090701 PMID:23129684 PMID:22366309 PMID:20036435 PMID:22981668