US lawFederal (United States)RegulationsTitle 21 CFR — Food and DrugsChapter I — FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICESPart 316 — ORPHAN DRUGSSubpart E — Open Protocols for Investigations316.4021 C.F.R. § 316.40Treatment use of a designated orphan drug.Last amended: 2016Year: 2026Length: 28 wordsOfficial source Cite as 21 C.F.R. § 316.40 (2026)Prospective investigators seeking to obtain treatment use of designated orphan drugs may do so as provided in subpart I of this chapter. [74 FR 40945, Aug. 13, 2009]