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Phosphodiesterase 10A (PDE10A) inhibition is a novel and promising approach for the treatment of central nervous system disorders such as schizophrenia and Huntington's disease. A novel PDE10A inhibitor, TAK-063 [1-[2-fluoro-4-(1H-pyrazol-1-yl)phenyl]-5-methoxy-3-(1-phenyl-1H-pyrazol-5-yl)-pyridazin-4(1H)-one] has shown high inhibitory activity and selectivity for human recombinant PDE10A2 in vitro; the half-maximal inhibitory concentration was 0.30 nM, and selectivity over other phosphodiesterases (PDEs) was more than 15000-fold. TAK-063 at 10 µM did not show more than 50% inhibition or stimulation of 91 enzymes or receptors except for PDEs. In vitro autoradiography (ARG) studies using rat brain sections revealed that [3H]TAK-063 selectively accumulated in the caudate putamen (CPu), nucleus accumbens (NAc), globus pallidus, substantia nigra, and striatonigral projection, where PDE10A is highly expressed. This [3H]TAK-063 accumulation was almost entirely blocked by an excess amount of MP-10, a PDE10A selective inhibitor, and the accumulation was not observed in brain slices of Pde10a-knockout mice. In rat brain sections, [3H]TAK-063 bound to a single high-affinity site with mean ± SEM dissociation constants of 7.2 ± 1.2 and 2.6 ± 0.5 nM for the CPu and NAc shell, respectively. Orally administered [14C]TAK-063 selectively accumulated in PDE10A expressing brain regions in an in vivo ARG study in rats. Striatal PDE10A occupancy by TAK-063 in vivo was measured using T-773 as a tracer and a dose of 0.88 mg/kg (p.o.) was calculated to produce 50% occupancy in rats. Translational studies with TAK-063 and other PDE10A inhibitors such as those presented here will help us better understand the pharmacological profile of this class of potential central nervous system drugs.

A 42-year-old man was admitted to our hospital because of lumbago and tachycardia-induced heart failure. Transthoracic echocardiography revealed impaired left ventricular function and a ball mass of thrombus in the left ventricle (LV). He was found to have systemic embolism in the spleen, kidneys, brain, and limbs. The patient was treated with limb thrombectomy followed by anticoagulation. Seven days after the direct factor Xa inhibitor, rivaroxaban, was initiated, transthoracic echocardiography was repeated, revealing disappearance of the LV thrombus without any clinical signs of cardiogenic embolism. His heart failure responded well and the LV wall motion had improved. This case suggests rivaroxaban has fibrinolytic effects on thrombi even in the LV.

In the title compound, C20H16O5, the dihedral angle between the naphthalene ring system and the benzene ring is 67.43 (5)°. The bridging carbonyl C—C(=O)—C plane makes dihedral angles of 82.64 (6) and 41.79 (7)°, respectively, with the naphthalene ring system and the benzene ring. The dihedral angle between the carboxy O—C(=O)—C plane and the benzene ring is 36.38 (7)° and that between the bridging carbonyl C—C(=O)—C plane and the carboxy O—C(=O)—C plane is 51.88 (8)°. The crystal structure is stabilized by intermolecular O—H...O and C—H...O hydrogen-bonding interactions. An intramolecular C—H...O hydrogen bond occurs between a naphthalene H atom and the carbonyl O atom of the carboxy group.

In the title compound, C19H15NO5, the dihedral angle between the naphthalene ring system and the benzene ring is 61.97 (5)°. The dihedral between the naphthalene ring system and the bridging carbonyl C—C(=O)—C plane is 54.68 (6)°, far larger than that [12.54 (7)°] between the phenyl group and the bridging carbonyl group. The nitro group and the phenyl ring are almost coplanar [O—N—C—C torsion angle = 2.94 (19)°]. In the crystal, molecules are linked by C—H...π interactions and the phenyl rings are involved in a centrosymmetric π–π interaction with a perpendicular distance of 3.523 Å and a lateral offset of 1.497 Å. In addition, weak intermolecular C—H...O hydrogen bonds are formed between an H atom of one methoxy group and a nearby carbonyl O atom.

In the title compound, C18H12BrClO3, the naphthalene ring system and the benzene ring make a dihedral angle of 82.18 (9)°. The conformation around the central C=O group is such that the C=O bond vector forms a larger angle to the plane of the naphthalene ring system than to the plane of the benzene ring, viz. 60.91 (16)° versus 13.94 (16)°. In the crystal structure, two π–π interactions formed between the naphthalene ring systems [centroid–centroid distances of 3.8014 (13) and 3.9823 (13) Å] and intermolecular O—H...O and C—H...O hydrogen bonds are present.

In the title compound, C21H18O5, the dihedral angle between the naphthalene ring system and the benzene ring is 86.65 (6)°. The bridging carbonyl C—C(=O)—C plane makes dihedral angles of 83.57 (7) and 20.21 (8)°, respectively, with the naphthalene ring system and the benzene ring. The ester O—C=O plane and the benzene ring are almost coplanar, making a dihedral angle of 3.81 (18)°. The two methoxy groups lie essentially in the naphthalene ring plane [C—O—C—C torsion angles = 2.1 (2) and −1.44 (19)°]. In the crystal structure, a centrosymmetric dimer is formed through C—H...O bonds connecting the 7-methoxy group and the carbonyl O atom of the ester group. The dimers are further linked by C—H...O hydrogen bonds between the methoxycarbonyl group and the bridging carbonyl O atom.

In the title compound, C26H18Br2O4, the two 4-bromobenzoyl groups at the 1- and 8-positions of the naphthalene ring system are anti to each other. The dihedral angle between the two benzene rings is 50.92 (14)°. The dihedral angles between the two benzene rings and the naphthalene ring system are 70.18 (11) and 74.98 (12)°. A weak intermolecular C—H...O hydrogen bond exists between the methyl group and the carbonyl O atom.

The title compound, C18H13ClO3, has an intramolecular O—H...O=C hydrogen bond between the carbonyl group and the hydroxy substituent on the naphthalene ring system. The angle between the C=O bond plane and the naphthalene ring system is relatively small [20.96 (8)°]. The angle between the benzene ring and the carbonyl group is rather large [35.65 (9)°] compared to that in an analogous compound [3.43 (11)°] having a methoxy group instead of a hydroxy substituent.

The molecule of the title compound, C14H14O2, lies on a crystallographic twofold axis perpendicular to the central C—C bond; there is one half-molecule in the asymmetric unit. The angle between the least-squares planes of the two aromatic rings is 66.94 (7)°. The methoxy group, with a twist angle of 10.69 (8)°, is slightly out of the plane of the benzene ring. In the crystal structure, C—H...π interactions are observed between adjacent molecules along the c-axis direction.

In the title compound, C19H15ClO3, the dihedral angle between the naphthalene ring system and the benzene ring is 72.06 (7)°. The 4-chlorophenyl group and the carbonyl group are almost coplanar. An intermolecular C—H...O hydrogen bond is formed between an H atom of the 4-chlorophenyl group and the O atom of one methoxy group, forming a zigzag chain along the a axis.

The molecule of the title compound, C26H20O4, is located on a twofold rotation axis. The two benzoyl groups are situated in an anti orientation. The dihedral angle between the mean planes of the phenyl ring and the naphthalene ring system is 80.25 (6)°. The phenyl and carbonyl groups in each benzoyl group are almost coplanar. The molecular packing is stabilized by weak C—H...O hydrogen bonds and a π–π stacking interaction between the phenyl rings [centroid–centroid and interplanar distances of 3.6383 (10) and 3.294 Å, respectively].

The title compound, C26H20O4, has an asymmetrical conformation at 193 K. The 4-acetylphenyl groups are twisted away from the the naphthalene ring system, with one benzene ring turned towards the 1-position of the naphthalene ring and the other benzene ring turned towards the 6-position. The interplanar angles between the mean planes of the benzene rings and the naphthalene ring system are 68.71 (6) and 74.01 (6)°. The structure displays C—H...O hydrogen bonding and π–π stacking interactions [centroid–centroid and interplanar distances are 3.5938 (9) and 3.517 Å, respectively].

In the title compound, C19H15ClO3, the interplanar angle between the naphthalene and benzene ring systems is 62.67 (6)°. The carbonyl group is twisted from both ring planes, with torsion angles of −44.9 (2)° with respect to the naphthalene ring and −26.7 (2)° with respect to the phenylene ring. There is an intermolecular hydrogen bond between an H atom of one methoxy group and the O atom of the second methoxy group, forming chains along the ac diagonal.