Patents by Inventor Norio Karibe

Norio Karibe has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6699870
    Abstract: The present invention provides a phthalazine compound as a therapeutic agent for erectile dysfunction represented by the following formula, a pharmacologically acceptable salt thereof or a hydrate thereof: wherein R1 and R2 are the same as or different from each other and represent a halogen atom, a C1 to C4 alkyl group which may be substituted with a halogen atom, a C1 to C4 alkoxy group which may be substituted with a halogen atom or a cyano group; X represents a cyano group, a nitro group, a halogen atom, a hydroxyimino group which may be substituted or a heteroaryl group which may be substituted; Y represents a heteroaryl group, an aryl group which may be substituted, an alkynyl group which may substituted, an alkenyl group, an alkyl group, an optionally substituted saturated or unsaturated 4- to 8-membered amine ring, and the cyclic amine compound is a monocyclic compound, bicyclic compound or a spiro compound; l is an integer of 1 to 3; provided that the case where l is 1 or 2, X is a
    Type: Grant
    Filed: October 28, 2002
    Date of Patent: March 2, 2004
    Assignee: Eisai Co., Ltd.
    Inventors: Nobuhisa Watanabe, Norio Karibe, Kazuki Miyazaki, Fumihiro Ozaki, Atsushi Kamada, Shuhei Miyazawa, Yoshimitsu Naoe, Toshihiko Kaneko, Itaru Tsukada, Tadashi Nagakura, Hiroki Ishihara, Kohtarou Kodama, Hideyuki Adachi
  • Publication number: 20030105074
    Abstract: The present invention provides a phthalazine compound as a therapeutic agent for erectile dysfunction represented by the following formula, a pharmacologically acceptable salt thereof or a hydrate thereof: 1
    Type: Application
    Filed: October 28, 2002
    Publication date: June 5, 2003
    Applicant: Eisai Co., Ltd.
    Inventors: Nobuhisa Watanabe, Norio Karibe, Kazuki Miyazaki, Fumihiro Ozaki, Atsushi Kamada, Shuhei Miyazawa, Yoshimitsu Naoe, Toshihiko Kaneko, Itaru Tsukada, Tadashi Nagakura, Hiroki Ishihara, Kohtarou Kodama, Hideyuki Adachi
  • Patent number: 6498159
    Abstract: The present invention provides a phthalazine compound as a therapeutic agent for erectile dysfunction represented by the following formula, a pharmacologically acceptable salt thereof or a hydrate thereof: wherein R1 and R2 are the same as or different from each other and represent a halogen atom, a C1 to C4 alkyl group which may be substituted with a halogen atom, a C1 to C4 alkoxy group which may be substituted with a halogen atom or a cyano group; X represents a cyano group, a nitro group, a halogen atom, a hydroxyimino group which may be substituted or a heteroaryl group which may be substituted; Y represents a heteroaryl group, an aryl group which may be substituted, an alkynyl group which may substituted, an alkenyl group, an alkyl group, an optionally substituted saturated or unsaturated 4- to 8-membered amine ring, and the cyclic amine compound is a monocyclic compound, bicyclic compound or a spiro compound; l is an integer of 1 to 3; provided that the case where l is 1 or 2, X is a
    Type: Grant
    Filed: March 8, 2000
    Date of Patent: December 24, 2002
    Assignee: Eisai Co., Ltd.
    Inventors: Nobuhisa Watanabe, Norio Karibe, Kazuki Miyazaki, Fumihiro Ozaki, Atsushi Kamada, Shuhei Miyazawa, Yoshimitsu Naoe, Toshihiko Kaneko, Itaru Tsukada, Tadashi Nagakura, Hiroki Ishihara, Kohtarou Kodama, Hideyuki Adachi
  • Patent number: 5919778
    Abstract: The cyclic amide derivative is defined by the formula (I) or a salt thereof: R1-(CH2)n-Z in which R1 is a group derived from a cyclic amide compound, substituted or unsubstituted, n is zero or an integer of 1 to 10 and Z is ##STR1## R2 being an aryl, a substituted aryl, a cycloalkyl or a heterocyclic group, m being an integer of 1 to 6, R3 being hydrogen or a lower alkyl, R4 being an aryl or a substituted aryl, a cycloalkyl or a heterocyclic group, p being an integer of 1 to 6, provided that the cyclic amide compound is quinazoline-on or quinazoline-dion, R2 and R4 are neither aryl nor substituted aryl. The cyclic amide compound is pharmacologically effective to prevent and treat diseases due to insufficiency of the central choline functions.
    Type: Grant
    Filed: May 25, 1995
    Date of Patent: July 6, 1999
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Masahiro Yonaga, Norio Karibe, Youichi Iimura, Satoshi Nagato, Atsushi Sasaki, Yoshiharu Yamanishi, Hiroo Ogura, Takashi Kosasa, Kumi Uchikoshi, Kiyomi Yamatsu
  • Patent number: 5654308
    Abstract: The cyclic amide derivative is defined by the formula (I) or a salt thereof: R.sup.1 --(CH.sub.2)n-Z in which R.sup.1 is a group derived from a cyclic amide compound, substituted or unsubstituted, n is zero or an integer of 1 to 10 and Z is ##STR1## R.sup.2 being an aryl, a substituted aryl, a cycloalkyl or a heterocyclic group, m being an integer of 1 to 6, R.sup.3 being hydrogen or a lower alkyl, R.sup.4 being an aryl or a substituted aryl, a cycloalkyl or a heterocyclic group, p being an integer of 1 to 6, provided that the cyclic amide compound is quinazoline-on or quinazoline-dion, R.sup.2 and R.sup.4 are neither aryl nor substituted aryl. The cyclic amide compound is pharmacologically effective to prevent and treat diseases due to insufficiency of the central choline functions.
    Type: Grant
    Filed: May 25, 1995
    Date of Patent: August 5, 1997
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Masahiro Yonaga, Norio Karibe, Youichi Iimura, Satoshi Nagato, Atsushi Sasaki, Yoshiharu Yamanishi, Hiroo Ogura, Takashi Kosasa, Kumi Uchikoshi, Kiyomi Yamatsu
  • Patent number: 5654306
    Abstract: A piperdine derivative having the formula (I) or a pharmacologically acceptable salt thereof:R.sup.1 --X--A--R.sup.2 (I)wherein R.sup.1 is selected from the group consisting of substituted or unsubstituted pyrazine, naphthalenedicarboxylic acid imide, bicyclo oct-5-ene-2,3-dicarboxylic acid imide and pyromellitimide;X is --(CH.sub.2).sub.n --, --O(CH.sub.2).sub.n --, --S(CH.sub.2).sub.n --, --NH(CH.sub.2).sub.n --, --SO.sub.1 NH(CH.sub.2).sub.n --, ##STR1## --CH.sub.2 NH(CH.sub.2).sub.n --, a group of the formula ##STR2## wherein n is an integer of 1 through 7 and R.sup.3 is hydrogen, lower alkyl or a benzyl, ##STR3## --O--CH.sub.2 CH.sub.2 CH.dbd. or ##STR4## R.sup.2 is hydrogen, lower alkyl, benzyl, benzyl substituted with hydroxy, methoxy or chlorine, benzoyl, benzyl with a fluorine substituent, pyridyl, 2-hydroxyethyl, pyridylmethyl or ##STR5## wherein Z represents a halogen atom.
    Type: Grant
    Filed: May 5, 1995
    Date of Patent: August 5, 1997
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Takaharu Nakamura, Yutaka Tsuchiya, Hiroyuki Sugumi, Kunizou Higurashi, Norio Karibe, Yoshiharu Yamanishi, Hiroo Ogura, Shin Araki, Atsuhiko Kubota, Michiko Ohtake, Kiyomi Tamatsu
  • Patent number: 5620976
    Abstract: The cyclic amide derivative is defined by the formula (I) or a salt thereof: R.sup.1 --(CH2)n--Z in which R.sup.1 is a group derived from a cyclic amide compound, substituted or unsubstituted, n is zero or an integer of 1 to 10 and Z is ##STR1## R.sup.2 being an aryl, a substituted aryl, a cycloalkyl or a heterocyclic group, m being an integer of 1 to 6, R.sup.3 being hydrogen or a lower alkyl, R.sup.4 being an aryl or a substituted aryl, a cycloalkyl or a heterocyclic group, p being an integer of 1 to 6, provided that the cyclic amide compound is quinazoline-on or quinazoline-dion, R2 and R4 are neither aryl nor substituted aryl. The cyclic amide compound is pharmacologically effective to prevent and treat diseases due to insufficiency of the central choline functions.
    Type: Grant
    Filed: May 25, 1995
    Date of Patent: April 15, 1997
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Masahiro Yonaga, Norio Karibe, Youichi Iimura, Satoshi Nagato, Atsushi Sasaki, Yoshiharu Yamanishi, Hiroo Ogura, Takashi Kosasa, Kumi Uchikoshi, Kiyomi Yamatsu
  • Patent number: 5523307
    Abstract: A cyclic amine is defined by the formula: ##STR1## in which A is naphthyl, phenyl, quinolyl or alkyl, X is a group containing carbonyl, n is 2 or 3 and B is alkyl, halogen, phenyl or --YZ, Y being --0--, --CO-- or --NH--, Z being phenyl, naphthyl, pyridyl, alkyl or cycloalkyl. It is useful to treat a mental symptoms associated with a cerebrovascular disease.
    Type: Grant
    Filed: June 7, 1994
    Date of Patent: June 4, 1996
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Takaharu Nakamura, Norio Karibe, Isao Saito, Kunizo Higurashi, Masahiro Yonaga, Takeru Kaneko, Takahiro Nakazawa, Masataka Ueno, Kiyomi Yamatsu, Kohshi Ueno, Masuhiro Ikeda
  • Patent number: 5521182
    Abstract: The cyclic amide derivative is defined by the formula (I) or a salt thereof:R.sup.1 --(CH.sub.2).sub.n --Zin whichR.sup.1 is a group derived from a cyclic amide compound, substituted or unsubstituted, n is zero or an integer of 1 to 10 and Z is ##STR1## R.sup.2 being an aryl, a substituted aryl, a cycloalkyl or a heterocyclic group, m being an integer of 1 to 6, R.sup.3 being hydrogen or a lower alkyl, R.sup.4 being an aryl or a substituted aryl, a cycloalkyl or a heterocyclic group, p being an integer of 1 to 6, provided that the cyclic amide compound is quinazoline-on or quinazoline-dion, R.sup.2 and R.sup.4 are neither aryl nor substituted aryl. The cyclic amide compound is pharmacologically effective to prevent and treat diseases due to insufficiency of the central choline functions.
    Type: Grant
    Filed: May 25, 1995
    Date of Patent: May 28, 1996
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Masahiro Yonaga, Norio Karibe, Youichi Iimura, Satoshi Nagato, Atsushi Sasaki, Yoshiharu Yamanishi, Hiroo Ogura, Takashi Kosasa, Kumi Uchikoshi, Kiyomi Yamatsu
  • Patent number: 5504088
    Abstract: The cyclic amide derivative is defined by the formula (I) or a salt thereof:R.sup.1 --(CH.sub.2).sub.n --Zin which R.sup.1 is a group derived from a cyclic amide compound, substituted or unsubstituted, n is zero or an integer of 1 to 10 and Z is ##STR1## R.sup.2 being an aryl, a substituted aryl, a cycloalkyl or a heterocyclic group, m being an integer of 1 to 6, R.sup.3 being hydrogen or a lower alkyl, R.sup.4 being an aryl or a substituted aryl, a cycloalkyl or a heterocyclic group, p being an integer of 1 to 6, provided that the cyclic amide compound is quinazoline-on or quinazoline-dion, R.sup.2 and R.sup.4 are neither aryl nor substituted aryl. The cyclic amide compound is pharmacologically effective to prevent and treat diseases due to insufficiency of the central choline functions.
    Type: Grant
    Filed: December 13, 1993
    Date of Patent: April 2, 1996
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Masahiro Yonaga, Norio Karibe, Youichi Iimura, Satoshi Nagato, Atsushi Sasaki, Yoshiharu Yamanishi, Hiroo Ogura, Takashi Kosasa, Kumi Uchikoshi, Kiyomi Yamatsu
  • Patent number: 5424318
    Abstract: A novel piperidine derivative is defined by the formula (I), including a salt thereof, ##STR1## wherein R.sup.1 denotes anthraquinone, X denotes a group of the formula --(CH.sub.2).sub.n --, a group of the formula --O(CH.sub.2).sub.n --, a group of the formula --S(CH.sub.2).sub.n --, a group of the formula --NH(CH.sub.2).sub.n --, a group of the formula --SO.sub.2 NH(CH.sub.2).sub.n --, a group of the formula ##STR2## a group of the formula ##STR3## a group of the formula ##STR4## a group of the formula --CH.sub.2 NH(CH.sub.2).sub.n --, a group of the formula ##STR5## (in all the above formulas, n is an integer of 1 through 7 and R.sup.3 represents a lower alkyl group or a benzyl group), a group of the formula ##STR6## a group of the formula ##STR7## a group of the formula --O--CH.sub.2 CH.sub.2 CH.dbd.
    Type: Grant
    Filed: January 5, 1994
    Date of Patent: June 13, 1995
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Takaharu Nakamura, Yutaka Tsuchiya, Hiroyuki Sugumi, Kunizou Higurashi, Norio Karibe, Yoshiharu Yamanishi, Hiroo Ogura, Shin Araki, Atsuhiko Kubota, Michiko Ohtake, Kiyomi Tamatsu
  • Patent number: 5306720
    Abstract: A novel piperidine derivative is defined by the formula (I), including a salt thereof, ##STR1## wherein R.sup.1 denotes a univalent group derived from substituted or unsubstituted quinazolinedione,X denotes a group of the formula ##STR2## n is an integer of 1 through 7, the ring A denotes a group of the formula ##STR3## a group of the formula ##STR4## or a group of the formula ##STR5## and R.sup.2 denotes a hydrogen atom, a lower alkyl group, a substituted benzoyl group, a pyridyl group, a 2-hydroxyethyl group, a pyridylmethyl group, or a group of the formula ##STR6## wherein Z represents a halogen atom). The novel compounds of this invention are used for treating dementias and sequelae of cerebrovascular diseases.
    Type: Grant
    Filed: December 20, 1991
    Date of Patent: April 26, 1994
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Takaharu Nakamura, Yutaka Tsuchiya, Hiroyuki Sugumi, Kunizou Higurashi, Norio Karibe, Yoshiharu Yamanishi, Hiroo Ogura, Shin Araki, Atsuhiko Kubota, Michiko Ohtake, Kiyomi Tamatsu
  • Patent number: 5292735
    Abstract: The cyclic amide derivative is defined by the formula (I) or a salt thereof: R1--(CH2)n-z in which R1 is a group derived from a cyclic amide compound, substituted or unsubstituted, n is zero or an integer of 1 to 10 and Z is ##STR1## R2 being an aryl, a substituted aryl, a cycloalkyl or a heterocyclic group, m being an integer of 1 to 6, R3 being hydrogen or a lower alkyl, R4 being an aryl or a substituted aryl, a cycloalkyl or a heterocyclic group, p being an integer of 1 to 6, provided that the cyclic amide compound is quinazoline-on or quinazoline-dion, R2 and R4 are neither aryl nor substituted aryl. The cyclic amide compound is pharmacologically effective to prevent and treat diseases due to insufficiency of the central choline functions.
    Type: Grant
    Filed: June 14, 1991
    Date of Patent: March 8, 1994
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Masahiro Yonaga, Norio Karibe, Youichi Iimura, Satoshi Nagato, Atsushi Sasaki, Yoshiharu Yamanishi, Hiroo Ogura, Takashi Kosasa, Kumi Uchikoshi, Kiyomi Yamatsu
  • Patent number: 5196439
    Abstract: A cyclic amine is defined by the formula: ##STR1## in which A is naphthyl, phenyl, quinolyl or alkyl, X is a group containing carbonyl, n is 2 or 3 and B is alkyl, halogen, phenyl or --YZ, Y being --O--, --CO-- or --NH--, Z being phenyl, naphthyl, pyridyl, alkyl or cycloalkyl. It is useful to treat mental symptoms associated with a cerebrovascular disease.
    Type: Grant
    Filed: January 24, 1992
    Date of Patent: March 23, 1993
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Takaharu Nakamura, Norio Karibe, Isao Saito, Kunizo Higurashi, Masahiro Yonaga, Takeru Kaneko, Takahiro Nakazawa, Masataka Ueno, Kiyomi Yamatsu, Kohshi Ueno, Masuhiro Ikeda
  • Patent number: 5118684
    Abstract: A novel piperidine derivative is defined by the formula (I), including a slt thereof, ##STR1## wherein R.sup.1 denotes a univalent group derived from one selected among substituted or unsubstituted benzene, pyridine, pyrazine, indole, anthraquinone, quinoline, substituted or unsubstituted phthalimide, homophthalimide, pyridinecarboxylic acid imide, pyridine N-oxide, pyrazinedicarboxylic acid imide, naphthalenedicarboxylic acid imide, substituted or unsubstituted quinazolinedione, 1,8-naphthalimide, bicyclo [2.2.2] oct-5-ene-2,3-dicarboxylic acid imide and pyromerylimide,X denotes a group of the formula --(CH.sub.2).sub.n --, a group of the formula --O(CH.sub.2).sub.n --, a group of the formula --S(CH.sub.2).sub.n --, a group of the formula --NH(CH.sub.2).sub.n --, a group of the formula --SO.sub.2 NH(CH.sub.2).sub.n --, a group of the formula ##STR2## a group of the formula ##STR3## a group of the formula ##STR4## a group of the formula --CH.sub.2 NH(CH.sub.2).sub.
    Type: Grant
    Filed: April 3, 1991
    Date of Patent: June 2, 1992
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Takaharu Nakamura, Yutaka Tsuchiya, Hiroyuki Sugumi, Kunizou Higurashi, Norio Karibe, Yoshiharu Yamanishi, Hiroo Ogura, Shin Araki, Atsuhiko Kubota, Michiko Ohtake, Kiyomi Tamatsu
  • Patent number: 5100901
    Abstract: A cyclic amine compound is defined by the formula: ##STR1## in which J is indanyl, indanonyl, indenyl, indenonyl, indanedionyl, tetralonyl, benzosuberonyl, indanolyl or a divalent group thereof, K is phenyl, an arylalkyl or cynnamyl, B is --(CHR22) r--, R22 being H or methyl, --CO-- (CHR22)r--, .dbd.(CH--CH.dbd.CH)b--, .dbd.CH--(CH2)c-- or .dbd.(CH--CH)d.dbd. and the ring including T and Q is piperidine. The compound is useful to treat senile dementia.
    Type: Grant
    Filed: October 18, 1989
    Date of Patent: March 31, 1992
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Yutaka Tsuchiya, Kunizou Higurashi, Norio Karibe, Youichi Iimura, Atsushi Sasaki, Yoshiharu Yamanishi, Hiroo Ogura, Shin Araki, Takashi Kosasa, Atsuhiko Kubota, Michiko Kosasa, Kiyomi Yamatsu
  • Patent number: 5039681
    Abstract: A novel piperidine derivative is defined by the formula (I), including a salt thereof, ##STR1## wherein R.sup.1 denotes a univalent group derived from one selected among substituted or unsubstituted benzene, pyridine, pyrazine, indole, anthraquinone, quinoline, substituted or unsubstituted phthalimide, homophthalimide, pyridinecarboxylic acid imide, pyridine N-oxide, pyrazinedicarboxylic acid imide, naphthalenedicarboxylic acid imide, substituted or unsubstituted quinazolinedione, 1,8-naphthalimide, bicyclo [2.2.2] oct-5-ene-2,3-dicarboxylic acid imide and pyromerylimide,X denotes a group of the formula --(CH.sub.2).sub.n --, a group of the formula --O(CH.sub.2).sub.n --, a group of the formula --S(CH.sub.2).sub.n --, a group of the formula --NH(CH.sub.2).sub.n --, a group of the formula --SO.sub.2 NH(CH.sub.2).sub.n --, a group of the formula ##STR2## a group of the formula ##STR3## a group of the formula ##STR4## a group of the formula --CH.sub.2 NH(CH.sub.2).sub.
    Type: Grant
    Filed: February 14, 1990
    Date of Patent: August 13, 1991
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Takaharu Nakamura, Yutaka Tsuchiya, Hiroyuki Sugumi, Kunizou Higurashi, Norio Karibe, Yoshiharu Yamanishi, Hiroo Ogura, Shin Araki, Atsuhiko Kubota, Michiko Ohtake, Kiyomi Tamatsu
  • Patent number: 4942169
    Abstract: A novel piperidine derivative is defined by the formula (I), including a salt thereof, ##STR1## wherein R.sup.1 denotes a univalent group derived from one selected among substituted or unsubstituted benzene, pyridine, pyrazine, indole, anthraquinone, quinoline, substituted or unsubstituted phthalimide, homophthalimide, pyridinecarboxylic acid imide, pyridine N-oxide, pyrazinedicarboxylic acid imide, naphthalenedicarboxylic acid imide, substituted or unsubstituted quinazolinedione, 1,8-naphthalimide, bicyclo [2.2.2.] oct-5-ene-2,3-dicarboxylic acid imide and pyromerylimide,X denotes a group of the formula --(CH.sub.2).sub.n --, a group of the formula --O(CH.sub.2).sub.n --, a group of the formula --S(CH.sub.2).sub.n --, a group of the formula --NH(CH.sub.2).sub.n --, a group of the formula --SO.sub.2 NH(CH.sub.2).sub.n --, a group of the formula ##STR2## a group of the formula ##STR3## a group of the formula ##STR4## a group of the formula --CH.sub.2 NH(CH.sub.2).sub.
    Type: Grant
    Filed: March 10, 1989
    Date of Patent: July 17, 1990
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Takaharu Nakamura, Yutaka Tsuchiya, Hiroyuki Sugumi, Kunizou Higurashi, Norio Karibe, Yoshiharu Yamanishi, Hiroo Ogura, Shin Araki, Atsuhiko Kubota, Michiko Ohtake, Kiyomi Tamatsu
  • Patent number: 4921863
    Abstract: Cyclic amine derivatives of the formula: ##STR1## or the pharmacologically acceptable salts thereof, wherein the symbols are as defined in the specification, as effective in relieving, curing or preventing mental symptoms due to cerebral vascular disorders.
    Type: Grant
    Filed: February 17, 1988
    Date of Patent: May 1, 1990
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Takaharu Nakamura, Norio Karibe, Isao Saito, Kunizou Higurashi, Masahiro Yonaga, Takeru Kaneko, Takahiro Nakazawa, Masataka Ueno, Kiyomi Yamatsu
  • Patent number: 4895841
    Abstract: A cyclic amine compound is defined by the formula: ##STR1## in which J is indanyl, indanonyl, indenyl, indenonyl, indanedionyl, tetralonyl, benzosuberonyl, indanolyl or a divalent group thereof, K is phenyl, an arylalkyl or cynnamyl, B is --(CHR22)r--, R22 being H or methyl, --CO--(CHR22)r--, .dbd.(CH--CH.dbd.CH)b--, .dbd.CH--(CH2)c-- or .dbd.(CH--CH)d.dbd. and the ring including T and Q is piperidine. The compound is useful to treat senile dementia.
    Type: Grant
    Filed: June 20, 1988
    Date of Patent: January 23, 1990
    Assignee: Eisai Co., Ltd.
    Inventors: Hachiro Sugimoto, Yutaka Tsuchiya, Kunizou Higurashi, Norio Karibe, Youichi Iimura, Atsushi Sasaki, Yoshiharu Yamanishi, Hiroo Ogura, Shin Araki, Takashi Kosasa, Atsuhiko Kubota, Michiko Kosasa, Kiyomi Yamatsu