[Pharmacological and clinical profile of inclisiran sodium, a long-acting LDL cholesterol lowering siRNA, LEQVIO for s.c. injection syringe 300†|mg].

Inclisiran sodium (Brand name: LEQVIO® for s.c. injection syringe 300 |mg, hereinafter referred to as inclisiran), a small interfering ribonucleic acid (siRNA) product that targets the mRNA that encodes the proprotein convertase subtilisin/kexin type 9 (PCSK9) protein was approved on September 25, 2023 for the indication of "Familial hypercholesterolemia, hypercholesterolemia" in Japan. Inclisiran is conjugated on the sense strand with triantennary N-acetylgalactosamine to facilitate uptake by hepatocytes. In vitro and in vivo pharmacology studies demonstrated the lowering effects of PCSK9 and LDL-C in hepatocytes and cynomolgus monkeys. It was considered unlikely to cause clinically significant risks due to toxicities arising from complementary binding to non-target RNA sequences (hybridization-dependent off-target effects). Clinical trials conducted globally including Japan in patients with familial hypercholesterolemia and hypercholesterolemia who did not reach the LDL-C target showed that inclisiran sodium 300 |mg dosed at Day 1, Day 90 and then every 6 months demonstrated significant LDL-C reduction and the efficacy sustained long. The majority of patients achieved the guideline recommended LDL-C targets. Inclisiran sodium 300 |mg was well tolerated and there were no specific safety concerns. Therefore, inclisiran is expected to be a new therapeutic option for the patients with familial hypercholesterolemia and hypercholesterolemia.

Pharmacological characterization and determination of pharmacokinetic and pharmacodynamic relationship of PF-00885706, a novel partial agonist selective for the 5-HT(4) receptor.

The pharmacological profile of PF-00885706, a selective 5-HT(4) receptor partial agonist, was investigated. PF-00885706 displayed a high binding affinity for the human 5-HT(4d) receptor with a K(i) of 3.7 nM that translates to functional agonist activity in vitro with EC(50) values of 4.0 nM and 6.6 nM in cell-based assays of human recombinant 5-HT(4d) receptors and rat tunica muscularis mucosae tissues, respectively. In both assays, partial agonism was confirmed with E(max) values of 84% and 78%, respectively. Notably, PF-00885706 was highly selective, displaying >1000-fold higher affinity for 5-HT(4d) receptors compared to 5-HT(1A), 5-HT(1B), 5-HT(1D), 5-HT(2A), 5-HT(2B), 5-HT(2C), 5-HT(3), 5-HT(7), and D(2long) receptors. Furthermore, in vitro binding assays demonstrated that PF-00885706 had no biologically significant interaction with physiologically important enzymes, ion channels including hERG channel, or receptors at concentrations up to 10 microM except for binding to the sigma(2) receptor. PF-00885706 exhibited weak binding affinity for the sigma(2) receptor yielding a K(i) value of 3 microM, which is more than 800-fold weaker than that for the 5-HT(4d) receptor. Oral administration of PF-00885706 to dogs resulted in marked and long-lasting stimulation of gastric motility with a minimum effective dose of 0.001 mg/kg. Pharmacokinetic analysis revealed that PF-00885706 has a low to moderate volume of distribution and the complete absorption in dogs. Pharmacokinetic and pharmacodynamic analysis of PF-00885706 in the dog gastric motility model showed a correlation between plasma concentrations and enhancement of gastric motility. Thus, PF-00885706 is an orally active, highly selective partial agonist for 5-HT(4) receptors that is expected to be effective for the treatment with gastrointestinal dysmotility disorders with reduced adverse effects mediated by other related receptors.

In vitro and in vivo pharmacological characterization of PF-01354082, a novel partial agonist selective for the 5-HT(4) receptor.

The pharmacological profile of PF-01354082, a selective 5-HT(4) receptor partial agonist, was investigated. PF-01354082 displayed high affinity for human 5-HT(4d) and dog 5-HT(4h) receptors in binding studies, having Ki values of 2.0 nM and 4.2 nM, respectively. By contrast, PF-01354082 did not show significant affinity for several other 5-HT receptors (5-HT(1A), 5-HT(1B), 5-HT(1D), 5-HT(2A), 5-HT(2B), 5-HT(2C), 5-HT(3A), and 5-HT(7)) or the dopamine D(2long) receptor. Functional assays using either cells expressing human recombinant 5-HT(4d) receptors or rat tunica muscularis mucosae demonstrated that PF-01354082 exhibited partial agonist activity at the 5-HT(4) receptor. The effects of PF-01354082 on in vitro receptor binding, ion channel activity, and sites of uptake were further investigated. PF-01354082 did not show biologically relevant binding activity at concentrations up to 10 microM except for binding to the 5-HT(4e) receptor. Furthermore, PF-01354082 decreased I(HERG) current by only 11% at a concentration of 300 microM, indicating that the compound had greater than 150,000-fold selectivity for the human 5-HT(4d) receptor over hERG channels. An in vivo study using a gastric motility model in conscious dogs demonstrated that oral administration of PF-01354082 resulted in marked and sustained stimulation of gastric motility in a dose-dependent manner. These results indicate that PF-01354082 is an orally active, highly selective, partial agonist of the human 5-HT(4) receptor that is expected to exert a favorable effect on gastrointestinal motor disorders with reduced adverse effects mediated by other related receptors.

Contribution of active and inactive states of the human 5-HT4d receptor to the functional activities of 5-HT4-receptor agonists.

In the present study, binding affinities of 5-hydroxytryptamine-4 (5-HT(4)) ligands for the human 5-HT(4d) receptor were determined using the agonist [(3)H]5-HT and the selective 5-HT(4) antagonist [(3)H]GR113,808. We also compared the affinity differences between [(3)H]5-HT binding (K(H)) and [(3)H]GR113,808 binding (K(L)) with their activities as 5-HT(4) ligands. Binding studies using [(3)H]5-HT revealed that the human 5-HT(4d) receptor has two binding sites, whereas [(3)H]GR113,808 yielded a single binding site. Additionally, the number of [(3)H]5-HT binding sites decreased in the presence of guanosine-5'-O-(3-thiotriphosphate) (GTPgammaS), but the number of [(3)H]GR113,808 sites did not change. In competitive binding assays, full agonists such as 5-methoxytryptamine and tegaserod showed 2- to 8-fold higher affinities for [(3)H]5-HT binding (K(H)) than for [(3)H]GR113,808 binding (K(L)) (K(H)K(L)). Finally, partial agonists displayed similar binding affinities for both radioligands (K(H) = K(L)). These findings suggest that the equilibrium between active and inactive states of the human 5-HT(4d) receptor relies on the functional activities of 5-HT(4) ligands, and these states affect the affinities of 5-HT(4) ligands in the competitive binding assay.

Involvement of central cannabinoid CB2 receptor in reducing mechanical allodynia in a mouse model of neuropathic pain.

We sought to examine the involvement of central cannabinoid CB2 receptor activation in modulating mechanical allodynia in a mouse model of neuropathic pain. JWH133 was demonstrated to be a selective cannabinoid CB2 receptor agonist in mice, reducing forskolin-stimulated cAMP production in CHO cells expressing mouse cannabinoid CB2 and cannabinoid CB1 receptors with EC50 values of 63 nM and 2500 nM, respectively. Intrathecal administration of JWH133 (50 and 100 nmol/mouse) significantly reversed partial sciatic nerve ligation-induced mechanical allodynia in mice at 0.5 h after administration. In contrast, systemic (intraperitoneal) or local (injected to the dorsal surface of the hindpaw) administration of JWH133 (100 nmol/mouse) was ineffective. Furthermore, the analgesic effects of intrathecal JWH133 (100 nmol/mouse) were absent in cannabinoid CB2 receptor knockout mice. These results suggest that the activation of central, but not peripheral, cannabinoid CB2 receptors play an important role in reducing mechanical allodynia in a mouse model of neuropathic pain.

5-Amino-6-chloro-N-[(1-isobutylpiperidin-4-yl)methyl]-2-methylimidazo[1,2-alpha]pyridine-8-carboxamide (CJ-033,466), a novel and selective 5-hydroxytryptamine4 receptor partial agonist: pharmacological profile in vitro and gastroprokinetic effect in conscious dogs.

5-Hydroxytryptamine (5-HT) receptors and dopamine(2) (D(2)) receptor modulate gastrointestinal motility. Gastroprokinetic agents that act on several 5-HT receptor subtypes and/or D(2) receptors are used clinically. Although the 5-HT(4) receptor is known to mediate the gastroprokinetic effects of these agents, the absence of highly selective 5-HT(4) receptor agonists has made it difficult to confirm the physiological consequences of selective 5-HT(4) receptor stimulation. In this study, we report the in vitro pharmacological profiles and the in vivo gastroprokinetic effects of 5-amino-6-chloro-N-[(1-isobutylpiperidin-4-yl)methyl]-2-methylimidazo[1,2-alpha]pyridine-8-carboxamide (CJ-033,466), a novel, potent, and selective 5-HT(4) partial agonist. Compared with preceding 5-HT(4) agonists such as cisapride, mosapride, and tegaserod, CJ-033,466 had a superior in vitro profile, with nanomolar agonistic activities for the 5-HT(4) receptor and 1000-fold greater selectivity for the 5-HT(4) receptor over other 5-HT and D(2) receptors. In vivo studies in conscious dogs showed that CJ-033,466 dose-dependently stimulated gastric antral motility in both the fasted and postprandial states at the same dose range and that it was 30 times more potent than cisapride. Furthermore, CJ-033,466 accelerated the gastric emptying rate in a gastroparesis dog model at the minimally effective dose established in the gastric motility study. In conclusion, CJ-033,466 is a potent and highly selective 5-HT(4) agonist that stimulates physiologically coordinated gastric motility, and it has no activity on other 5-HT receptor subtypes and D(2) receptors. Therefore, CJ-033,466 could be used to treat gastroparesis, providing better gastroprokinetics and reduced side effects mediated by the other receptors.

T+31C polymorphism of angiotensinogen gene and nocturnal blood pressure decline: the Ohasama study.

BACKGROUND: We assessed the association between several polymorphisms of angiotensinogen gene (AGT) and essential hypertension using ambulatory blood pressure (BP). METHODS: We recruited 802 subjects in a rural Japanese community who were aged >40 years and who gave written informed consent for monitoring of their ambulatory BP and genetic analysis (the Ohasama Study). As a polymorphism of AGT, T+31C, which is in complete linkage disequilibrium with M235T, was determined using the TaqMan polymerase chain reaction method. RESULTS: The genotype distribution of AGT/T-+31C in the Ohasama Study was similar to that in another large Japanese population. Although there was no significant difference in 24-h and daytime ambulatory BP values, the nighttime BP was significantly lower in the subjects with TT, resulting in greater decline of nocturnal systolic (P = .090) and diastolic (P = .025) BP in subjects with TT. CONCLUSIONS: AGT/T+31C is associated with the circadian BP variation but not with BP level in the Japanese general population.