Abstract
Drug repurposing (drug repositioning, drug reprofiling, drug retasking) gains increasing importance as the development of new drugs becomes increasingly expensive. Though only a few compounds have been approved for new indications in the field of metabolic disorders, there are a number of substances which have the potential to become reprofiled in a new indication. Generally, reprofiled drugs for metabolic disorders can be classified in three groups. Group A contains those of which both, the original and repurposed indication, concern metabolic disorders. Group B comprises drugs, which were originally approved for non-metabolic disorders but show beneficial effects for metabolic disorders after repurposing. Group C comprises drugs, which were originally approved for metabolic disorders and are effective for non-metabolic disorders in their repurposed indication. Repurposed drugs in the field of metabolic disorders of group A include tetra-hydrobiopterin, originally indicated for phenylketonuria and now also approved for tetrahydrobiopterindeficiency, coenzyme-Q, originally approved for primary coenzyme-Q deficiency and reprofiled for statin-myopathy, and colesevelam, originally approved to reduce elevated low-density lipoprotein (LDL)-cholesterol (LDL-C) and now being approved for type-2-diabetes. An example of group C is phenylbutyrate, which was originally approved for urea-cycle disorders and meanwhile gained approval for progressive familial intrahepatic cholestasis type 2 due to mutations in the ABCB11 gene. Still additional compounds used to treat metabolic (non-metabolic) disorders show promising effects in non-metabolic (metabolic disorders) after repurposing in cell and tissue models. Future investigations will need to identify which candidate drugs may leave the pipeline status to acquire approval for new indications.
Keywords: Metabolic disorders, metabolism, repurposing, new indication, reprofiling, retasking, drug development.