1. Office of Clinical Pharmacology, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland, USA
2. Current affiliation: Hefei University of Technology A-Level Center, Hefei, Anhui, China
3. Controlled Substance Staff, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland, USA
4. Current affiliation: Hertz and Fields Consulting, Inc., Silver Spring, Maryland, USA
5. Division of Anesthesia, Analgesia, and Addiction Products, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
6. Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland, USA