Coding Symbols for Thesaurus of Adverse Reaction Terms (COSTART). 5th ed. Rockville (MD). COSTART is used for coding, filing, and retrieving post-marketing adverse drug and biologic experience reports. COSTART is organized in body system and pathophysiology hierarchies, as well as a separate fetal/neonatal category of less than 20 terms. COSTART has been superseded by the Medical Dictionary for Regulatory Activities (MedDRA) Terminology. For more information about MedDRA in the Metathesaurus, see the MedDRA source synopsis. COSTART was last updated in the Metathesaurus in 1999.