1. Department of Anesthesiology and Pain Relief Center, The University of Tokyo Hospital, Hongo 7-3-1, Bunkyoku, Tokyo 113-8655, Japan
2. Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Kami Kitazawa 2-1-6, Setagayaku, Tokyo 156-0057, Japan
3. Department of Oral Health and Clinical Science, Tokyo Dental College, Kanda Misakichou 2-9-18, Chiyodaku, Tokyo 101-0061, Japan
4. Department of Dental Anesthesiology, Tokyo Dental College, Kanda Misakichou 2-9-18, Chiyodaku, Tokyo 101-0061, Japan
5. Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyoku, Tokyo 113-8655, Japan
6. Department of Clinical Laboratory Medicine, The University of Tokyo Hospital, Hongo 7-3-1, Bunkyoku, Tokyo 113-8655, Japan
7. Department of Pain and Palliative Medicine, The University of Tokyo Hospital, Hongo 7-3-1, Bunkyoku, Tokyo 113-8655, Japan