1. Drug Analysis Department Laboratory of Racing Chemistry 1731‐2 Tsuruta‐machi, Utsunomiya Tochigi 320‐0851 Japan
2. Department of Pharmaceutical Sciences Tohoku University Hospital 1‐1 Seiryo‐machi, Aoba‐ku Sendai Miyagi 980‐8574 Japan
3. Research Planning & Coordination Division, JRA Equine Research Institute 1400‐4, Shiba, Shimotsuke Tochigi 329‐0412 Japan
4. Veterinarian Section, Equine Department, Japan Racing Association 6‐11‐1 Roppongi, Minato‐ku Tokyo 105‐0003 Japan