N-(6-phenylpyridazin-3-yl)benzenesulfonamides as highly potent, brain-permeable, and orally active kynurenine monooxygenase inhibitors.

Huntington's disease (HD) is one of the serious neurodegenerative diseases and no disease modifiers are available to date. The correction of unbalanced kynurenine pathway metabolites may be useful to treat disease progression and kynurenine monooxygenase (KMO) is considered an ideal drug target. A couple of KMO inhibitors have been reported, but their brain permeability was very poor. We found pyridazinylsulfonamide as a novel lead compound, and it was optimized to the brain-permeable and highly potent KMO inhibitor 12, which was equipotent with CHDI-340246 and superior to CHDI-340246 in terms of brain penetration. Compound 12 was effective in R6/2 mice (HD model mice), i.e. neuroprotective kynurenic acid was increased, whereas neurotoxic 3-hydroxykynurenine was suppressed. In addition, impaired cognitive function was improved. Therefore, the brain-permeable KMO inhibitor was considered to be a disease modifier for HD treatment.

Double-blind, placebo-controlled study of lurasidone monotherapy for the treatment of bipolar I depression.

AIM: Previous studies conducted primarily in the USA and Europe have demonstrated the efficacy and safety of lurasidone 20-120 mg/day for the treatment of bipolar I depression. The aim of the current study was to evaluate the efficacy and safety of lurasidone monotherapy for the treatment of bipolar I depression among patients from diverse ethnic backgrounds, including those from Japan. METHODS: Patients were randomly assigned to double-blind treatment for 6 weeks with lurasidone, 20-60 mg/day (n = 184) or 80-120 mg/day (n = 169), or placebo (n = 172). The primary end-point was change from baseline to Week 6 on the Montgomery-Åsberg Depression Rating Scale (MADRS). RESULTS: Lurasidone treatment significantly reduced mean MADRS total scores from baseline to Week 6 for the 20-60-mg/day group (-13.6; adjusted P = 0.007; effect size = 0.33), but not for the 80-120-mg/day group (-12.6; adjusted P = 0.057; effect size = 0.22) compared with placebo (-10.6). Treatment with lurasidone 20-60 mg/day also improved MADRS response rates, functional impairment, and anxiety symptoms. The most common adverse events associated with lurasidone were akathisia and nausea. Lurasidone treatments were associated with minimal changes in weight, lipids, and measures of glycemic control. CONCLUSION: Monotherapy with once daily doses of lurasidone 20-60 mg, but not 80-120 mg, significantly reduced depressive symptoms and improved functioning in patients with bipolar I depression. Results overall were consistent with previous studies, suggesting that lurasidone 20-60 mg/day is effective and safe in diverse ethnic populations, including Japanese.

Organic anion transporter 3 mediates the efflux transport of an amphipathic organic anion, dehydroepiandrosterone sulfate, across the blood-brain barrier in mice.

The present study investigated the efflux transport systems of organic anions across the blood-brain barrier (BBB) using dehydroepiandrosterone sulfate (DHEAS) as a probe. The elimination of DHEAS from the brain after microinjection into the cerebral cortex was characterized in wild-type mice and mice with deficiency of well characterized organic anion transporters, organic anion-transporting polypeptide 1a4 (Oatp1a4)/Slco1a4 and organic anion transporter 3 (Oat3)/Slc22a8, at the BBB. The saturable efflux of DHEAS from the brain was completely inhibited by probenecid, benzylpenicillin, and estrone-3-sulfate and moderately inhibited by taurocholate and p-aminohippurate (50-57%). Uptake of DHEAS and estrone-3-sulfate was greater in murine Oat3 cRNA-injected oocytes than that in water-injected oocytes. Efflux of these compounds from the brain was significantly delayed in Oat3(-/-) mice compared with that in wild-type mice, indicating that indeed Oat3 is functionally important in vivo. Furthermore, probenecid and taurocholate inhibited DHEAS efflux completely in Oat3(-/-) mice. Contrary to the past report in rats that suggested involvement of Oatp1a4, specific uptake of DHEAS and estrone-3-sulfate by murine Oatp1a4 was not detected in vitro, and efflux of both compounds from the brain was not altered in Oatp1a4(-/-) mice. There was no significant difference in the uptake of DHEAS by brain slices prepared from wild-type, Oatp1a4(-/-), and Oat3(-/-) mice. Taken together, these results suggest that Oat3 plays a significant role in the efflux of steroid conjugates across the BBB in mice and that the BBB also expresses other unknown organic anion transporters for the efflux of DHEAS. Transport mechanisms of organic anions at the BBB are far more diverse than they were assumed to be.

Lurasidone in the long-term treatment of Japanese patients with bipolar I disorder: a 52 week open label study.

BACKGROUND: The current study evaluated the long-term (52 week) safety and impact on symptom measures of lurasidone (with or without lithium or valproate) for the treatment of bipolar I disorder in Japanese patients. METHODS: Bipolar patients for this open-label flexibly dosed lurasidone (20-120 mg/day) study were recruited from those with a recent/current depressive episode who completed an initial 6 week, double-blind, placebo-controlled, lurasidone study (depressed group), and those with a recent/current manic, hypomanic, or mixed episode (non-depressed group) who agreed to enroll directly into the long-term study. Measures of adverse events and safety included treatment-emergent adverse events, vital signs, body weight, ECG, laboratory tests, and measures of suicidality and extrapyramidal symptoms. Symptom measures included Montgomery Åsberg Depression Rating Scale (MADRS) and Young Mania Rating Scale (YMRS). RESULTS: The most common adverse events associated with lurasidone were akathisia (30.7%), nasopharyngitis (26.6%), nausea (12.1%), and somnolence (12.1%). Minimal changes in lipids and measures of glycemic control occurred. Mean change in body weight was + 1.0 kg in the non-depressed group and - 0.8 kg in the depressed group. MADRS total scores declined by a mean (SD) of 2.0 (14.7) points from long-term baseline to endpoint in the depressed group who had received placebo in the prior 6 week trial. The depressed group that had received lurasidone during the prior 6 week study maintained their depressive symptom improvements. For the non-depressed group, YMRS total scores decreased over time. LIMITATIONS: No control group was included, treatment was open-label, and 49.7% of patients completed the 52 week study. CONCLUSIONS: Long-term treatment with lurasidone 20-120 mg/day for Japanese patients with bipolar disorder maintained improvements in depressive symptoms for depressed patients who were treated in a prior 6 week trial and led to improvements in manic symptoms among a newly recruited subgroup of patients with a recent/current manic, hypomanic, or mixed episode. Few changes in weight or metabolic parameters were evident. CLINICAL TRIAL REGISTRATION: JapicCTI-132319, clinicaltrials.gov-NCT01986114.

Lurasidone in the Long-Term Treatment of Bipolar I Depression: A 28-week Open Label Extension Study.

BACKGROUND: Lurasidone has demonstrated efficacy for short-term treatment of bipolar depression in a diverse ethnic population including Japanese. This study evaluated the long-term safety and effectiveness of open-label lurasidone treatment in these patients. METHODS: Patients for this 28-week extension study were recruited from those who completed a 6-week double-blind study of lurasidone, 20-60 mg/day, lurasidone 80-120 mg/day, and placebo. In the extension study, lurasidone was flexibly dosed (20 to 120 mg/day). Safety was evaluated in terms of change from extension-phase baseline to endpoint including adverse events, vital signs, body weight, ECG, laboratory tests, and measures of suicidality and extrapyramidal symptoms. Effectiveness was determined by Montgomery Åsberg Depression Rating Scale (MADRS) and other measures. RESULTS: 303 of 413 (73.3%) subjects completed the extension study. Discontinuation due to a treatment-emergent adverse event occurred for 11.4% of those who received placebo, and 8.9% of those who received lurasidone, in the prior 6-week trial. The most common treatment-emergent adverse event was akathisia. Minimal changes were evident on body weight and metabolic parameters. Long-term treatment with lurasidone further reduced mean MADRS total scores from long-term baseline to week 28 (or endpoint) for both those who had received prior placebo (-11.3), and those who had receive prior lurasidone (-8.9), in the 6-week double-blind trial. LIMITATIONS: There was no placebo control and treatment was not double-blind. CONCLUSIONS: Long-term treatment with lurasidone (20-120 mg/day) was well-tolerated with no new safety concerns and associated with continued improvement in depressive symptoms in this international sample of patients with bipolar depression. CLINICAL TRIAL REGISTRATION: JapicCTI-132319, clinicaltrials.gov - NCT01986114.

Functional characterization of mouse organic anion transporting peptide 1a4 in the uptake and efflux of drugs across the blood-brain barrier.

This study investigated the role of a multispecific organic anion transporter, Oatp1a4/Slco1a4, in drug transport across the blood-brain barrier. In vitro transport studies using human embryonic kidney 293 cells expressing mouse Oatp1a4 identified the following compounds as Oatp1a4 substrates: pitavastatin (K(m) = 8.3 microM), rosuvastatin (K(m) = 12 microM), pravastatin, taurocholate (K(m) = 40 microM), digoxin, ochratoxin A, and [d-penicillamine(2,5)]-enkephalin. Double immunohistochemical staining of Oatp1a4 with P-glycoprotein (P-gp) or glial fibrillary acidic protein demonstrated that Oatp1a4 signals colocalized with P-gp signals partly but not with glial fibrillary acidic protein, suggesting that Oatp1a4 is expressed in both the luminal and the abluminal membranes of mouse brain capillary endothelial cells. The brain-to-blood transport of pitavastatin, rosuvastatin, pravastatin, and taurocholate after microinjection into the cerebral cortex was significantly decreased in Oatp1a4(-/-) mice compared with that in wild-type mice. The blood-to-brain transport of pitavastatin, rosuvastatin, taurocholate, and ochratoxin A, determined by in situ brain perfusion, was significantly lower in Oatp1a4(-/-) mice than in wild-type mice, whereas transport of pravastatin and [D-penicillamine(2,5)]-enkephalin was unchanged. The blood-to-brain transport of digoxin was significantly lower in Oatp1a4(-/-) mice than in wild-type mice only when P-gp was inhibited by N-(4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)ethyl]-phenyl)-9,10-dihydro-5-methoxy-9-oxo-4-acridine carboxamide (GF120918). Taken together, these results show that Oatp1a4 can mediate the brain-to-blood and blood-to-brain transport of its substrate drugs across the blood-brain barrier. The brain-to-plasma ratio of taurocholate, pitavastatin, and rosuvastatin was close to the capillary volume in wild-type mice, and it was not affected by Oatp1a4 dysfunction. Whether Oatp1a4 can deliver drugs from the blood to the brain remains controversial.

L-type calcium channel modulates mechanosensitivity of the cardiomyocyte cell line H9c2.

The application of mechanical stimuli to cells often induce increases in intracellular calcium, affecting the regulation of a variety of cell functions. Although the mechanism of mechanotransduction-induced calcium increases has not been fully resolved, the involvement of mechanosensitive ion channels in the plasma membrane and the endoplasmic reticulum has been reported. Here, we demonstrate that voltage-gated L-type calcium channels play a critical role in the mechanosensitive calcium response in H9c2 rat cardiomyocytes. The intracellular calcium level in H9c2 cells increased in a reproducible dose-dependent manner in response to uniaxial stretching. The stretch-activated calcium response (SICR) completely disappeared in calcium-free medium, whereas thapsigargin and cyclopiazonic acid, inhibitors of sarcoendoplasmic reticulum calcium ATPase, partially reduced the SICR. These findings suggest that both calcium influx across the cell membrane and calcium release from the sarcoendoplasmic reticulum are involved in the SICR. Nifedipine, diltiazem, and verapamil, inhibitors of L-type calcium channels, reduced the SICR in a dose-dependent manner. Furthermore, small interfering RNA against the L-type calcium channel α1c subunit diminished the SICR dramatically. Nifedipine also diminished the mechanosensitivity of Langendorff-perfused rat heart. These results suggest that the SICR in H9c2 cardiomyocytes involves the activation of L-type calcium channels and subsequent calcium release from the sarcoendoplasmic reticulum.

Investigation of the effect of active efflux at the blood-brain barrier on the distribution of nonsteroidal aromatase inhibitors in the central nervous system.

The brain distribution of nonsteroidal aromatase inhibitors was investigated in mice to understand their interactions with brain aromatase. The brain-to-plasma ratio (Kp,brain , mL/g brain) of anastrozole was 0.0299 ± 0.0068, which was lower than that of letrozole (0.383 ± 0.048) and vorozole (0.185 ± 0.031) despite their similar physicochemical properties. The brain-to-plasma unbound concentration ratio of anastrozole, measured using microdialysis, was 0.118 ± 0.037 mL/g brain. In situ mouse brain perfusion also demonstrated that the uptake clearance [mL/(min·g brain)] of anastrozole by the brain (0.108 ± 0.018) was lower than that for letrozole and vorozole (0.422 ± 0.068 and 0.910 ± 0.152, respectively). Anastrozole and vorozole were transported by P-glycoprotein (P-gp) in vitro, whereas none of the compounds were transported by breast cancer resistance protein (BCRP). The Kp,brain of anastrozole and vorozole were increased by 12- and 3.3-fold, respectively, in Mdr1a/b/Bcrp(-/-) mice. IC50 (nM) of anastrozole and letrozole against human aromatase was 12.9 ± 0.7 and 3.59 ± 0.75, respectively. Taken together, these results suggest that active efflux mediated by P-gp at the blood-brain barrier limits the effect of anastrozole in the central nervous system, whereas vorozole and letrozole easily traverse the barrier.