1. The Chemical and Formulation Research Laboratories, Lederle (Japan), Ltd., Kashiwa-cho, Shiki, Saitama 353-8511, Japan, Rigaku Corporation, 3-9-12 Matsubara-cho, Akishima-shi, Tokyo 196-8666, Japan, and Faculty of Pharmaceutical Sciences, The University of Tokushima, Sho-machi, Tokushima 770-8505, Japan