Abstract: The present invention provides a solid preparation comprising a crystal of [3-[(2R)-[[(2R)-(3-chlorophenyl)-2-hydroxyethyl]amino]propyl]-1H-indol-7-yloxy]acetic acid (Compound A), especially a crystal of Compound A having a particle size of not larger than 100 &mgr;m at the cumulative weight distribution value of 50%, and not larger than 200 &mgr;m at the cumulative weight distribution value of 95%, preferably a solid preparation having the excellent stability and the content uniformity of Compound A, which is prepared by preparing granules of the crystal of Compound A with fillers, disintegrants and binders, and then followed by mixing said granules with external excipients.

Abstract: A 5-substituted-3-oxadiazolyl-1,6-naphthyridin-2(1H)-one derivative of the formula (I): wherein Het is oxadiazolyl, R1 is H, lower alkyl, cyclo-lower alkyl, trifluoromethyl, lower alkenyl, lower alkynyl, lower alkoxy, lower alkoxy-lower alkyl, hydroxy-lower alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaromatic group, and R2 is H, lower alkyl, cyclo-lower alkyl, cyclo-lower alkylmethyl, lower alkenyl, cyclo-lower alkenyl, lower alkynyl, substituted or unsubstituted aryl, or substituted or unsubstituted hetero-aromatic group, or a pharmaceutically acceptable acid addition salt thereof, which has high selective affinity to benzodiazepine receptor and is useful particularly as a benzodiazepine inverse agonist, for example, as psychoanaleptic drug or a drug for the treatment of dysmnesia in senile dementia or Alzheimer's disease.

Abstract: A 5-substituted-3-oxadiazolyl-1,6-naphthyridin-2(1H)-one derivative of the formula (I): wherein Het is oxadiazolyl, R1 is H, lower alkyl, cyclo-lower alkyl, trifluoromethyl, lower alkenyl, lower alkynyl, lower alkoxy, lower alkoxy-lower alkyl, hydroxy-lower alkyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaromatic group, and R2 is H, lower alkyl, cyclo-lower alkyl, cyclo-lower alkylmethyl, lower alkenyl, cyclo-lower alkenyl, lower alkynyl, substituted or unsubstituted aryl, or substituted or unsubstituted heteroaromatic group, or a pharmaceutically acceptable acid addition salt thereof, which has high selective affinity to benzodiazepine receptor and is useful particularly as a benzodiazepine inverse agonist, for example, as psychoanaleptic drug or a drug for the treatment of dysmnesia in senile dementia or Alzheimer's disease.

Abstract: 3-Oxadiazolyl-5,6,7,8-tetrahydro-1,6-naphthyridine derivative of the formula (I): ##STR1## wherein Het is an oxadiazole ring, R.sub.1 is hydrogen atom, an acyl group, a lower alkyl group or a group of the formula: --CH.sub.2 R.sub.1 ' (in which R.sub.1 ' is a cyclo-lower alkyl group, a lower alkenyl group, a lower alkynyl group, benzyl group, aryl group or a heteroaromatic group), R.sub.2 is a lower alkyl group, a cyclo-lower alkyl group, a lower alkenyl group, a lower alkynyl group, aryl group, a heteroaromatic group, a halogeno-lower alkyl group, a lower alkoxy-lower alkyl group, a lower alkoxy group, a lower alkenyloxy group, a phenoxy group or a lower alkylthio group, or a pharmaceutically acceptable acid addition salt thereof, which are useful as benzodiazepine receptor agonist.

Abstract: 3-Oxadiazolyl-5,6,7,8-tetrahydro-1,6-naphthyridine derivative of the formula (I): ##STR1## wherein Het is an oxadiazole ring, R.sub.1 is hydrogen atom, an acyl group, a lower alkyl group or a group of the formula: --CH.sub.2 R.sub.1' (in which R.sub.1' is a cyclo-lower alkyl group, a lower alkenyl group, a lower alkynyl group, benzyl group, aryl group or a heteroaromatic group), R.sub.2 is a lower alkyl group, a cyclo-lower alkyl group, a lower alkenyl group, a lower alkynyl group, aryl group, a heteroaromatic group, a halogeno-lower alkyl group, a lower alkoxy-lower alkyl group, a lower alkoxy group, a lower alkenyloxy group, a phenoxy group or a lower alkylthio group, or a pharmaceutically acceptable acid addition salt thereof, which are useful as benzodiazepine receptor agonist.

Abstract: 3-Oxadiazolyl-5,6,7,8-tetrahydro-1,6-naphthyridine derivative of the formula (I): ##STR1## wherein Het is an oxadiazole ring, R.sub.1 is hydrogen atom, an acyl group, a lower alkyl group or a group of the formula: --CH.sub.2 R.sub.1 ' (in which R.sub.1 ' is a cyclo-lower alkyl group, a lower alkenyl group, a lower alkynyl group, benzyl group, aryl group or a heteroaromatic groups), R.sub.2 is a lower alkyl group, a cyclo-lower alkyl group, a lower alkenyl group, a lower alkynyl group, aryl group, a heteroaromatic group, a halogeno-lower alkyl group, a lower alkoxy-lower alkyl group, a lower alkoxy group, a lower alkenyloxy group, a phenoxy group, or a lower alkylthio group, or a pharmaceutically acceptable acid addition salt thereof, which are useful as benzodiazedine receptor agonist.