Toshifumi Shiraga
Keio University
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Publication
Featured researches published by Toshifumi Shiraga.
Journal of Ocular Pharmacology and Therapeutics | 2008
Eriko Fujita; Yoshinori Teramura; Toshifumi Shiraga; Shin-Ichi Yoshioka; Takafumi Iwatsubo; Akio Kawamura; Hidetaka Kamimura
PURPOSE The aim of this study was to investigate the ocular distribution of tacrolimus (FK506) and absorption into the systemic circulation after a single or repeated topical instillation of FK506 ophthalmic suspension in male New Zealand white rabbits. METHODS In the single instillation study (group 1), 29.1-34.8 microL of a 0.1, 0.3, and 1% suspension was administered to each of the 15 rabbits. In the repeated instillation study (group 2), 27.1-39.5 microL of a 0.3% suspension was administered to 27 rabbits q.i.d. (i.e., at 3-h intervals) for 14 days. In the intravenous (i.v.) dose study (group 3), 1 mg/kg of FK506 was administered to 3 rabbits. The amount of FK506 was measured by using a competitive enzyme immunoassay. RESULTS The results for single and repeated instillation studies were similar. In the single instillation study, blood T(max) after an instillation of the 0.1, 0.3, and 1% suspensions (at 0.8, 1.0, and 1.0 hours) did not differ significantly among these doses. One (1) h after an instillation of the 1% suspension, ocular tissue concentrations, except the retina/choroid, vitreous body, and lens, were higher than the blood concentration (C(max): 2.7 ng/mL). In particular, concentrations in the conjunctiva, cornea, iris, and anterior sclera were much higher than the blood concentration (148, 900, 120, and 145 ng/g tissue). In the repeated instillation study, concentrations in the blood and ocular tissues (except the lens) reached a steady state by the 7th day. In the i.v. dose study, AUC(0-24h) and T(1/2) were 1643 ng h/mL and 18.5 h, respectively. CONCLUSIONS The high-level distribution of FK506 was observed in the conjunctiva, which is desirable because the conjunctiva is the target tissue for pharmacologic effect (i.e., efficacy).
Biological & Pharmaceutical Bulletin | 2005
Toshiro Niwa; Toshifumi Shiraga; Akira Takagi
Drug Metabolism and Disposition | 1999
A. Möller; Kazuhide Iwasaki; Akio Kawamura; Y. Teramura; Toshifumi Shiraga; Takehisa Hata; A. Schäfer; N. A. Undre
Drug Metabolism and Disposition | 1993
Kazuhide Iwasaki; Toshifumi Shiraga; K Nagase; Z Tozuka; K Noda; S Sakuma; T Fujitsu; K Shimatani; A Sato; M Fujioka
Drug Metabolism and Disposition | 1995
Kazuhide Iwasaki; Toshifumi Shiraga; H Matsuda; K Nagase; Y Tokuma; T Hata; Y Fujii; S Sakuma; T Fujitsu; A Fujikawa
Journal of Mass Spectrometry | 2003
Zenzaburo Tozuka; Hayato Kaneko; Toshifumi Shiraga; Yasuyuki Mitani; Manabu Beppu; Shigeyuki Terashita; Akio Kawamura; Akira Kagayama
Biological & Pharmaceutical Bulletin | 2005
Toshiro Niwa; Toshifumi Shiraga; Ikuko Ishii; Akira Kagayama; Akira Takagi
Journal of Biochemistry | 1998
Kouichi Yoshinari; Kiyoshi Nagata; Makoto Ogino; Ken-ichi Fujita; Toshifumi Shiraga; Kazuhide Iwasaki; Takehisa Hata; Yasushi Yamazoe
Biological & Pharmaceutical Bulletin | 2005
Toshifumi Shiraga; Zenzaburo Tozuka; Rika Ishimura; Akio Kawamura; Akira Kagayama
Carcinogenesis | 1993
Hiroshi Yamazaki; Mayumi Mimura; Yoshimitsu Oda; Yukiharu Inui; Toshifumi Shiraga; Kazuhide Iwasaki; F. Peter Guengerich; Tsutomu Shimada