Amelioration of collagen-induced arthritis in mice by a novel phosphodiesterase 7 and 4 dual inhibitor, YM-393059

YM-393059 is a novel phosphodiesterase (PDE) 7 and PDE4 dual inhibitor that inhibits PDE7A with high potency (IC50=14 nM) and PDE4 with moderate potency (IC50=630 nM). It inhibits lipopolysaccharide (LPS)-induced tumor necrosis factor-alpha production in mice with an ED50 value of 2.1 mg/kg [Yamamoto, S., Sugahara, S., Naito, R., Ichikawa, A., Ikeda, K., Yamada, T., Shimizu, Y., 2006. The effects of a novel phosphodiesterase 7A and -4 dual inhibitor, YM-393059, on T-cell-related cytokine production in vitro and in vivo. Eur. J. Pharmacol. 541, 106-114.]. In this study, we investigated the therapeutic potential of YM-393059 for the treatment of rheumatoid arthritis in several animal models. YM-393059 was found to inhibit LPS-induced interleukin (IL)-1beta production in mice with an ED50 value of 16.6 mg/kg, but it had only a slight effect on IL-6 production. YM-393059 and cyclosporine significantly suppressed arthritis development at doses of 30-100 mg/kg and 20 mg/kg, respectively, in the mice collagen-induced arthritis model. YM-393059 (100 mg/kg) significantly inhibited increases in the serum immunoglobulin G level that occurred in response to autoantigenic collagen in arthritic mice, whereas cyclosporine (20 mg/kg) did not. In contrast, cyclosporine completely suppressed the acute rejection of cardiac allografts in rats, whereas YM-393059 did not, even at a dose of 100 mg/kg. YM-393059 potently inhibited proinflammatory cytokine production and selectively suppressed the response to the autoantigen without affecting the response to alloantigens. These results suggest that YM-393059 is an attractive compound for the treatment of autoimmune disorders such as rheumatoid arthritis.     

Cardiovascular effects of a novel, potent and selective phosphodiesterase 5 inhibitor, DMPPO: in vitro and in vivo characterization.

1. The aim of this study was to investigate the cardiovascular effects of a novel, potent and specific phosphodiesterase 5 (PDE 5) inhibitor, 1,3 dimethyl-6-(2-propoxy-5-methane sulphonylamidophenyl)-pyrazolo[3,4-d]pyrimidin-4-(5H)-one (DMPPO) in phenylephrine-precontracted rat aortic rings and different in vivo rat preparations. 2. DMPPO elicited a concentration-dependent relaxation of rat aortic rings with functional endothelium. DMPPO-induced relaxation was abolished by endothelium removal or pretreatment with the soluble guanylate cyclase inhibitor, methylene blue (10 microM). 3. In aortic rings without endothelium, the potency (pD2= -log10 EC50) of atrial natriuretic peptide (ANP) to induce relaxation increased from 8.13 +/- 0.05 in the absence of DMPPO, to 8.32 +/- 0.05 and 8.52 +/- 0.08 in the presence of 30 nM and 100 nM DMPPO, respectively. Similarly, the potency of sodium nitroprusside (SNP) in inducing relaxation increased from 7.38 +/- 0.07 in the absence of the PDE 5 inhibitor to 8.07 +/- 0.11 and 8.15 +/- 0.08 in the presence of 30 nM and 100 nM DMPPO, respectively. In contrast, relaxation to the adenylate cyclase activator, forskolin, was unchanged by DMPPO (100 nM). 4. In rings without endothelium, DMPPO (100 nM) increased by 2.5 fold intracellular levels of guanosine 3':5'-cyclic monophosphate (cyclic GMP). Moreover, DMPPO (100 nM) potentiated the increases in cyclic GMP levels induced by ANP (30 nM) by 3 fold and SNP (30 nM) by 2.7 fold. Adenosine 3':5'-cyclic monophosphate (cyclic AMP) levels were not modified by DMPPO. 5. In anaesthetized normotensive or spontaneously hypertensive rats (SHR), DMPPO (2 and 5 mg kg-1, i.v.) lowered blood pressure without affecting heart rate. Similarly, in conscious SHR, orally administered DMPPO (5 mg kg-1) induced a 25 mmHg decrease in blood pressure for at least 7 h without modifying heart rate. Meanwhile, urinary cyclic GMP was increased by 50% whereas cyclic AMP remained unchanged. 6. In normotensive anaesthetized rats, sodium nitroprusside (SNP) (i.v. bolus) induced a decrease in blood pressure which rapidly returned to baseline. In DMPPO (1 mg kg-1, i.v.)-treated rats, the hypotensive effects of SNP (10 to 100 micrograms kg-1) were prolonged over time whereas the peak effect was unchanged. 7. In pithed rats, phenylephrine (i.v. bolus) induced dose-dependent increases in blood pressure. Pretreatment with DMPPO (5 mg kg-1, i.v.) partially inhibited the pressor response to phenylephrine (0.3 to 100 micrograms kg-1). 8. In conclusion, the potent and selective PDE 5 inhibitor, DMPPO, produces relaxation in isolated vessels in the presence of a cyclic GMP drive and reduces blood pressure of intact animals. Its high oral bioavailability and long duration of action should make it a useful tool to study the role of cyclic GMP in various biological systems.     

Anti-asthmatic effect of ASP3258, a novel phosphodiesterase 4 inhibitor

ASP3258 is a potent and selective PDE4 inhibitor and exerts a wide-range of anti-inflammatory effects with low emetic potential, a major adverse effect of PDE4 inhibitors. Here, we investigated the anti-asthmatic potency of ASP3258 as compared with those of two representative PDE4 inhibitors: roflumilast and cilomilast. Orally administered ASP3258, roflumilast, and cilomilast all inhibited ovalbumin (OVA)-induced eosinophil infiltration into the airway of sensitized Brown Norway rats with ED(50) values of 0.81, 0.46, and 4.4 mg/kg, respectively. Histological examination also revealed a decreasing trend in inflammatory cell infiltration into the lung following ASP3258 administration. In vitro investigation of bronchodilatory activities showed that these compounds (10(-8)-10(-6) M) concentration-dependently inhibited OVA-induced contraction of trachea isolated from sensitized guinea pigs but had no effect on spasmogen-precontracted tracheal tension prepared from non-sensitized guinea pigs up to 10(-6) M. In vivo experiments using sensitized guinea pigs showed that these orally administered compounds inhibited OVA-induced increases in airway resistance with ED(50) values of 2.2, 0.35, and 12 mg/kg, respectively. Further, orally administered ASP3258 (0.1 and 1 mg/kg), roflumilast (0.1 and 1 mg/kg), and cilomilast (10 mg/kg) significantly suppressed airway hyperresponsiveness caused by OVA exposure. ASP3258's potent inhibition of antigen-induced bronchoconstriction and airway hyperresponsiveness, two characteristic symptoms of bronchial asthma, suggests that this compound will be useful in treating asthma.     

In vitro pharmacology of R 80122, a novel phosphodiesterase inhibitor.

The cardiac in vitro effects of R 80122, a novel phosphodiesterase (PDE) inhibitor, were investigated and compared with those of the reference compound milrinone and of the calcium-sensitizer adibendan. In guinea pig left atria, both milrinone and R 80122 increased contractile force; 10 microM milrinone was equieffective to 1 microM R 80122. The rate of spontaneously beating atria was not altered by R 80122 in the concentration range of 0.01-0.3 microM. Higher concentrations (1-10 microM) led to a statistically insignificant increase of 20%. Milrinone's effect on frequency was more pronounced and amounted to 21% at 10 microM and to 40% at 100 microM. Adibendan increased heart rate (HR) by 10% at a concentration of only 0.03 microM. This effect was not enhanced any further by increasing the concentration. In papillary muscle, the positive inotropic effects of both milrinone and R 80122 were inhibited by carbachol, indicating involvement of cyclic AMP. Further indications for a cyclic AMP-dependent action were obtained by induction of slow action potentials and synergism with isoprenaline. In electrophysiologic measurements, milrinone reduced action potential duration (APD) in a high concentration whereas R 80122 had no effect. Action potential changes elicited by a toxic concentration of ouabain were reduced by R 80122. Relaxation of rat aortic rings contracted by KCl and relaxation of guinea pig aortic rings contracted by norepinephrine (NE) was comparable for both milrinone and R 80122. R 80122 also caused relaxation of canine coronary arteries constricted with prostaglandin F2 alpha (PGF2 alpha) both with and without endothelium. NE-induced contractions in canine gastrosplenic arteries were not affected by R 80122. Cardiac contractility that had been impaired to various degrees by pentobarbital or by aging was restored to control values by both milrinone and R 80122. R 80122 enhanced cardiac contractility at lower concentrations than milrinone with no concomitant increase in frequency or shortening of the action potential, which may be advantageous for treatment of heart failure.     

In vitro effects of cilostazol,a phosphodiesterase 3A inhibitor,on mouse oocyte maturation and morphology

相似文献   

In vitro and in vivo interactions of nitrovasodilators and zaprinast, a cGMP-selective phosphodiesterase inhibitor.

We have examined the interaction of zaprinast, a selective inhibitor of cGMP phosphodiesterase, with guanylate cyclase activators on vascular smooth muscle relaxation in vitro and in vivo. Isolated porcine coronary arterial rings precontracted with prostaglandin F2 alpha (PGF2 alpha) were relaxed dose dependently by the guanylate cyclase activators nitroglycerin and nitroprusside, the cGMP phosphodiesterase inhibitor zaprinast and the endothelium-dependent agent bradykinin. A 1 h pretreatment with 0.5 mM nitroglycerin shifted the dose-response curve to nitroglycerin to the right by a factor of 90, reflecting the development of tolerance. The dose-response curve to sodium nitroprusside was also affected, albeit to a much lesser degree (9-fold increase in IC50). Both zaprinast and bradykinin remained unaffected by nitroglycerin pretreatment. A 30 min pretreatment of rings with zaprinast (1 microM) had no effect on nitroglycerin- or nitroprusside-induced relaxation in control rings, but enhanced vasorelaxation to both nitrovasodilators 7- and 2-fold, respectively, in tolerant rings. Similarly, a 30 min pretreatment of rings with 0.1 microM nitroprusside enhanced zaprinast-induced vasorelaxation 4- and 8-fold, respectively, in control and tolerant rings. Similar observations were made in vivo in anesthetized spontaneously hypertensive rats where zaprinast (0.1-3.0 mg/kg i.v.), caused dose-dependent reductions in mean arterial pressure. This effect was enhanced when rats had been pretreated with nitroprusside (1 micrograms/kg per min). In comparison, in zaprinast-pretreated rats the magnitude of depressor responses to nitroprusside (0.5-5.0 micrograms/kg) was not altered, but the duration of hypotensive response to the highest dose of nitroprusside was enhanced by zaprinast. These data demonstrate an enhanced vasodilatory response of nitrocompounds in combination with peak I-selective phosphodiesterase inhibitors.     

Attenuation of inflammation and cytokine production in rat colitis by a novel selective inhibitor of leukotriene A4 hydrolase

BACKGROUND AND PURPOSE: Leukotriene B(4) (LTB(4)), formed by the sequential actions of the 5-lipoxygenase (5-LO) and leukotriene A(4) hydrolase (LTA(4)H), is a pro-inflammatory mediator implicated in the pathogenesis of inflammatory bowel disease. However, inhibitors of 5-LO have not proved to be consistent in their therapeutic efficacy in colitis. Another approach to inhibiting LTB(4) synthesis is through the use of inhibitors of LTA(4)H, such as the novel, potent and selective compound, JNJ 26993135. EXPERIMENTAL APPROACH: The effect of oral administration of JNJ 26993135 has been evaluated in a rat model of colitis provoked by colonic instillation of trinitrobenzenesulphonic acid (TNBS). The extent and severity of the macroscopic inflammatory response, the colonic levels of myeloperoxidase (MPO) and LTB(4) and of the pro-inflammatory cytokines, tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were measured. KEY RESULTS: Oral administration of JNJ 26993135 (5, 15 and 30 mg kg(-1), twice a day) dose-dependently reduced both the extent and intensity of the colonic inflammatory damage observed 3 days after TNBS challenge. JNJ 26993135 also dose-dependently reduced the elevated colonic levels of LTB(4), as well as the inflammatory biomarkers, MPO, IL-6 and TNF-alpha. This dosing regimen was supported by the pharmacokinetic profile of JNJ 26993135, along with the demonstration of the inhibition of ex vivo production of LTB(4) in whole blood following oral administration. CONCLUSIONS AND IMPLICATIONS: These results with JNJ 26993135 in the rat TNBS model support the role of LTB(4) in colitis and the potential value of targeting LTA(4)H for the treatment of inflammatory bowel diseases.     

In vitro and in vivo characterization of XR11576, a novel, orally active, dual inhibitor of topoisomerase I and II

XR11576, a novel phenazine, was developed as an inhibitor of both topoisomerase I and II. This study characterized the ability of XR11576 to inhibit both enzymes, and determined its in vitro and in vivo antitumor efficacy against a number of murine and human tumor models. XR11576 was a potent inhibitor of purified topoisomerase I and IIalpha, and exhibited similar potency for both enzymes. The compound stabilized enzyme-DNA cleavable complexes indicating that it acted as a topoisomerase poison. The DNA cleavage patterns obtained with XR11576 were different from those induced by camptothecin and etoposide, which are topoisomerase I and II poisons, respectively. XR11576 demonstrated potent cytotoxic activity against a variety of human and murine tumor cell lines (IC50=6-47 nM). Its activity profile was comparable to or better than that of many widely used anticancer drugs. Moreover, XR11576 was unaffected by multidrug resistance (MDR) mediated by overexpression of either P-glycoprotein or MDR-associated protein, or by down-regulation of topoisomerase II. The latter property supports the dual inhibitory mechanism of action of the compound. XR11576 exhibited a similar pharmacokinetic profile in mice and rats after either i.v. or p.o. administration. In vivo XR11576 showed marked efficacy against a number of tumors including sensitive (H69/P) and multidrug-resistant (H69/LX4) small cell lung cancer and the relatively refractory MC26 and HT29 colon carcinomas following i.v. and p.o. administration. The efficacy of XR11576 was at least comparable to that of TAS-103, originally proposed as a dual inhibitor of topoisomerase I and II. These results suggest that XR11576 is a promising new antitumor agent with oral and i.v. activity, and warrants further development.     

Anti-neutrophilic inflammatory activity of ASP3258, a novel phosphodiesterase type 4 inhibitor

Neutrophil-dominant pulmonary inflammation is an important feature of chronic obstructive pulmonary disease (COPD). Here, we evaluated the in vitro and in vivo anti-neutrophilic inflammatory activities of ASP3258, a novel, orally active, and selective phosphodiesterase (PDE) 4 inhibitor with anti-inflammatory potency comparable to that of second-generation compound roflumilast but with lower emetic activity in vivo. In in vitro experiments using human peripheral blood neutrophils, PDE4 inhibitors ASP3258, cilomilast, and roflumilast inhibited fMLP-induced superoxide production in a concentration-dependent manner with IC50 values of 5.0, 96, and 4.7 nM, respectively. ASP3258, cilomilast, and roflumilast also attenuated fMLP-induced neutrophil chemotaxis in a concentration-dependent manner with IC30 values of 18, 270, and 9.7 nM, respectively. In contrast, the glucocorticoid prednisolone inhibited neither superoxide production nor chemotaxis up to 1 μM. In a rat model of lipopolysaccharide (LPS)-induced lung inflammation, orally administered ASP3258, cilomilast, roflumilast, and prednisolone (at 10 or 30 mg/kg) dose-dependently attenuated pulmonary accumulation of neutrophils. The inhibitory effect of ASP3258 was more potent than cilomilast and almost the same as roflumilast and prednisolone. Treatment with ASP3258 inhibited the elevation of TNF-α in the bronchoalveolar lavage fluid following LPS instillation. Histological examination revealed significant inhibition of neutrophil and macrophage infiltration into alveoli by ASP3258. Overall, these findings suggest that ASP3258 has therapeutic potential for treating neutrophilic inflammation such as COPD, partly through direct inhibition of neutrophil activation as well as possibly through inhibition of the TNF-α-mediated pathway.     

In vitro effects of E3040, a dual inhibitor of 5-lipoxygenase and thromboxane A(2) synthetase, on eicosanoid production.

In vitro pharmacological profiles of E3040, 6-hydroxy-5, 7-dimethyl-2-(methylamino)-4-(3-pyridylmethyl) benzothiazole were investigated. Against the 5-lipoxygenase activity of rat basophilic leukemia cells, E3040 and zileuton (a 5-lipoxygenase inhibitor) had an IC(50) of 0.23 and 0.93 microM, respectively. Against the thromboxane A(2) synthetase activity of human platelets, E3040 had an IC(50) of 0.01 microM, which was comparable to that of OKY-1581 (sodium (E)-3-[4-(3-pyridylmethyl) phenyl]-2-methylacrylate, a thromboxane A(2) synthetase inhibitor). Against cyclooxygenase activity of sheep seminal vesicles, E3040 showed no inhibition (IC(50), >300 microM). Sulfasalazine and 5-aminosalicylic acid, therapeutic drugs for inflammatory bowel disease, inhibited 5-lipoxygenase activity with an IC(50) of 293 and 970 microM, respectively. Sulfasalazine inhibited thromboxane A(2) synthetase activity with an IC(50) of 20 microM. In rat peritoneal leukocytes, E3040 inhibited leukotriene B(4) and thromboxane B(2) production with an IC(50) of 0.17 and 0.24 microM, respectively. E3040 inhibited leukotriene B(4) production in human neutrophils and thromboxane B(2) production in human platelets (IC(50) of 0.21 and 0.09 microM, respectively). These results indicated that E3040 potently inhibited 5-lipoxygenase and thromboxane A(2) synthetase and blocked leukotriene B(4) and thromboxane B(2) production in rat peritoneal and human blood cells.     

The effects of olprinone, a phosphodiesterase 3 inhibitor, on systemic and cerebral circulation

Olprinone, a phosphodiesterase (PDE) 3 inhibitor, is used to treat heart failure due to its positive inotropic and vasodilative effects. Selective inhibition of the PDE 3 isozyme increases intracellular adenosine 3;5;-cyclic monophosphate and enhances Ca(2+) influx into cardiac muscle cells. The most significant advantage of PDE 3 inhibitors is their ability not only to enhance myocardial contraction, but to reduce, through vasodilatory action, the stress to which the heart is subjected. In peripheral vessels, the decrease of cytosolic free Ca(2+) induces the vasorelaxation of vascular smooth muscle cells. In this way, olprinone reduces mean aortic and pulmonary artery pressures. Additionally, olprinone exerts differential vasodilatory effects on peripheral vessels in each organ, based on the differences in the distribution of PDE 3 among the organs. With respect to the cerebral circulation, olprinone augments blood flow in the cerebral cortex through direct vasodilatory effects on small cerebral arteries or arterioles. Olprinone increases hepatosplanchnic blood flow and improves oxygen supply. While long-term therapy with PDE 3 inhibitors in patients with chronic heart failure may accelerate the progress of the underlying disease and provoke serious ventricular arrhythmia, olprinone shows good potential for short-term treatment in patients who have experienced severe heart failure or patients who have undergone cardiac surgery.     

新一代胸苷酸合成酶抑制剂ZD1694的体内外抗肿瘤作用

目的:观察ZD1694对小鼠体内S180肉瘤生长的抑制作用及其在体外对人胃腺癌SGC-7901细胞增殖的影响.方法:采用荷瘤小鼠模型,腹腔注射不同剂量的ZD1694,分单次给药与连续 5 d 分次给药两种方案.处死动物后称取肿瘤组织重量,计算抑瘤率.另外采用MTT比色法及流式细胞仪观察ZD1694对人SGC-7901胃腺癌细胞株生长的影响.结果:ZD1694可抑制小鼠体内S180肉瘤的生长,其抑瘤率无论是单次给药组(200、100、50 mg·kg-1)还是连续 5 d 给药组(40、20、10 mg·kg-1·d-1),均可见剂量依赖性增加.ZD1694(0.001～1 000 mmol·L-1)对SGC-7901人胃腺癌细胞的生长抑制率呈浓度依赖性和时间依赖性增加,可使G0-G1期细胞增多, S期和G2-M期细胞减少.结论:ZD1694对荷瘤小鼠产生明显的抗瘤作用,一次性给药的抑瘤率大于相同剂量分5次给药的抑瘤率.该药在体外可抑制人胃腺癌SGC-7901细胞生长,使细胞发生G1期阻滞.     

Relaxant effect of YM976, a novel phosphodiesterase 4 inhibitor,on bovine tracheal smooth muscle

Effects of 4-(3-chlorophenyl)-1,7-diethylpyrido[2,3-d]pyrimidin-2(1H)-one (YM976), a novel and selective phosphodiesterase type 4 inhibitor, on tension and adenosine 3',5'-cyclic monophosphate (cAMP) content of bovine tracheal smooth muscle were compared with those of rolipram and theophylline. YM976, rolipram and theophylline relaxed the tracheal preparations contracted with histamine in a concentration-dependent manner. The relaxant effects of YM976 and rolipram were more potent than those of theophylline. These phosphodiesterase inhibitors-induced relaxations were dramatically diminished when tracheal smooth muscle was contracted with methacholine instead of histamine. Pretreatment of the tracheal preparations with YM976 (10 microM) or rolipram (10 microM), but not with theophylline (1 mM), shifted the concentration-response curves for contractile responses to histamine; however, the same procedure failed to affect concentration-response relationships for methacholine-induced contractions. At 1 and 10 microM, both YM976 and rolipram increased the tissues cAMP content. These results suggest that YM976 relaxes tracheal smooth muscle, probably through the cAMP-dependent mechanism.     

The effects of siguazodan, a selective phosphodiesterase inhibitor, on human platelet function

1. The effects of siguazodan (SK&F 94836) a selective phosphodiesterase (PDE) inhibitor with inotropic and vasodilator activity, were studied on human platelets. 2. Siguazodan selectively inhibited the major cyclic AMP-hydrolysing PDE in human platelet supernatants. The inhibited enzyme has been variously termed cyclic GMP-inhibited PDE or PDE-III. 3. In platelet-rich plasma (PRP), siguazodan inhibited U46619-induced aggregation more potently than that induced by ADP and collagen. Treatment of the PRP with aspirin had no effect on the potency of siguazodan. 4. In washed platelets, siguazodan increased cyclic AMP levels and reduced cytoplasmic free calcium [( Ca2+]i). ADP decreased the ability of siguazodan to raise cyclic AMP and this may explain its lower potency in inhibiting responses to ADP. 5. Siguazodan has anti-platelet actions over the same concentration range that it is an inotrope and vasodilator.     

Antiplatelet and antithrombotic effects of a novel selective phosphodiesterase 3 inhibitor, NSP-513, in mice and rats

We investigated the effects of NSP-513, (R)-4,5-dihydro-5-methyl-6-[4-(2-propyl-3-oxo-1-cyclohexenyl)amino] phenyl-3(2H)-pyridazinone, on phosphodiesterase (PDE) isozyme activities, in vitro platelet aggregation and in vivo thrombus formation. NSP-513 selectively inhibited human platelet PDE 3 isozyme with an IC50 value of 0.039 microM. In an in vitro human platelet aggregation assay, the IC50 values (microM) of NSP-513 for platelet aggregation induced by collagen, U-46619, arachidonic acid, adenosine diphosphate (ADP), epinephrine and thrombin were 0.31, 0.25, 0.082, 0.66, 0.23 and 0.73, respectively. In a mouse pulmonary thromboembolism model, orally administered NSP-513 showed in vivo antithrombotic effects that were 320 to 470 times more potent than those of cilostazol. In a rat carotid arterial thrombosis model, intraduodenally administered NSP-513 (0.1 mg/kg), cilostazol (30 mg/kg) and aspirin (30 mg/kg) reduced thrombus formation by 75%, 66% and 48%, respectively. However, intravenously administered dipyridamole (10 mg/kg) did not significantly prevent thrombus formation. These results demonstrate that NSP-513 has the potential to prevent not only in vitro platelet aggregation but also in vivo thrombus formation and indicate that the highly selective PDE 3 inhibitory effect of NSP-513 may make this compound useful for assessing the physiological role of PDE 3.     

The inotropic effects of UK 14,275, a phosphodiesterase inhibitor, in man.

1. UK 14,275 (Pfizer) an inotropic agent with cardiac phosphodiesterase inhibitory activity, was administered to ten healthy male volunteers. 2. The inotropic activity was assessed by non-invasive measurement of systolic time intervals (STI). 3. The compound had significant inotropic activity in the doses administered, as judged by the shortening of pre-ejection period (PEP), without any significant chronotropic activity. 4. The inotropic effect was abolished when measurements were repeated following beta-adrenoceptor blockade with oral propranolol. 5. The inotropic activity was compared to that of intravenous isoprenaline.     

Effect of YM-44781, YM-44778 and YM-49598, novel tachykinin antagonists, in a drug-induced bladder contraction model

The radioligand binding profiles and in vivo pharmacological characteristics of YM-44781, YM-44778 and YM-49598, novel non-peptide tachykinin receptor antagonists, were examined and compared to those of FK-888 and GR-159897. Since no functional NK(3) receptors were found in the rat bladder, the emphasis will be on the other two subtypes. YM-44781 and YM-49598 exhibited high binding affinities at NK(2) (pK(i) = 9.94 +/- 0.03) and NK(1) (pK(i) = 9.09 +/- 0.02) receptors, respectively, whereas YM-44778 exhibited high binding affinities at both NK(1) (pK(i) = 8.08 +/- 0.07) and NK(2) (pK(i) = 8.55 + 0.04) receptors stably transfected in CHO-K1 cells (Chinese hamster ovary cells). In an in vivo rat model, a drug-induced bladder contraction model, antagonism of the contractions produced by the selective NK(2) receptor agonist, [betaAla8]neurokinin A (4-10) (10 microg x kg(-1) i.v.) was observed after intravenous administration (dose range 0.001-1 mg x kg(-1)) of YM-44781 and YM-44778 (IC(50) = 27 +/- 8 and 100 +/- 44 microg x kg(-1), respectively). YM-44781 was more potent (about 3-fold) than YM-44778. YM-49598 was almost inactive but produced a potent inhibition (IC(50) = 11 +/- 7 microg x kg(-1)) of the contraction of the rat urinary bladder induced by challenge with the NK(1)-selective receptor agonist [Sar9,Met(O(2))11]substance P sulphone (0.3 microg x kg(-1)). YM-44781 and YM-44778 did not produce major inhibition of [Sar9,Met(O(2))11]substance P-induced bladder contraction. These findings indicate that YM-44781 and YM-49598 are potent NK(2) and NK(1) receptor antagonists, respectively, whereas YM-44778 is a nonselective NK(2)/NK(1) receptor antagonist in the drug-induced bladder contraction model.     

The canine CYP1A2 deficiency polymorphism dramatically affects the pharmacokinetics of 4-cyclohexyl-1-ethyl-7-methylpyrido[2,3-D]-pyrimidine-2-(1H)-one (YM-64227), a phosphodiesterase type 4 inhibitor.

In a previous study, it was shown that the novel canine single nucleotide polymorphism (SNP) CYP1A2 1117C>T yields an inactive enzyme. In this study, the effect that this SNP has on the pharmacokinetics of 4-cyclohexyl-1-ethyl-7-methylpyrido[2,3-d]pyrimidine-2-(1H)-one (YM-64227) was investigated. Plasma concentrations of the unchanged drug and five of its metabolites (MM-1 to MM-5) were determined after either intravenous or oral administration of YM-64227 to genotyped dogs (C/C, C/T, and T/T groups). Liver microsomes were prepared from these dogs to determine the in vitro metabolic clearance of YM-64227. After a single oral administration, the maximum plasma concentration and absolute bioavailability of YM-64227 in the T/T group were 17.1 times and 27.2 times higher than those in the C/C group, respectively, whereas the pharmacokinetics of YM-64227 after intravenous administration were not affected by genotype. The metabolic profiles in the T/T group were quite distinct from the others; i.e., the main metabolite was MM-2 in the C/C group, whereas MM-1 and MM-5 were the main metabolites in the T/T group. The formation clearances of MM-2 and MM-3 in the microsomes derived from T/T type dogs were significantly lower, whereas those of MM-1, MM-4, and MM-5 were not affected. A statistically significant correlation was observed between the in vivo and in vitro metabolic intrinsic clearances (r = 0.82, p < 0.001). The canine CYP1A2 1117C>T SNP proved to be responsible for a substantial portion of the interindividual variability in the pharmacokinetics of YM-64227.     

YM-53601, a novel squalene synthase inhibitor,suppresses lipogenic biosynthesis and lipid secretion in rodents

1. To better understand how it decreases plasma cholesterol and triglyceride levels, we evaluated the effect of (E)-2-[2-fluoro-2-(quinuclidin-3-ylidene)ethoxy]-9H-carbazole monohydrochloride(YM-53601) on lipogenic biosynthesis in the liver and lipid secretion from the liver in rats and hamsters. 2. Single administration of YM-53601 in cholestyramine-treated rats inhibited triglyceride and free fatty acid (FFA) biosynthesis at a similar dose range to that at which it inhibited cholesterol biosynthesis. YM-53601 inhibited both triglyceride and FFA biosynthesis in hamsters treated with cholestyramine. 3. YM-53601 by single oral administration decreased the enhanced plasma triglyceride levels in hamsters induced by an injection of protamine sulfate, which inhibits lipoprotein lipase (LPL) and consequently increases plasma very low-density lipoprotein (VLDL) triglyceride levels. YM-53601 also decreased the enhanced plasma triglyceride and cholesterol levels in hamsters treated with Triton WR1339, which also inhibits the degradation of VLDL. Plasma cholesterol was significantly decreased as soon as 1 h after single administration of YM-53601 in hamsters fed a normal diet. 4. This is the first report that a squalene synthase inhibitor suppresses lipogenic biosynthesis in the liver and cholesterol and triglyceride secretion from the liver in vivo. We therefore suggest that the mechanism by which YM-53601 decreases plasma triglyceride might include these effects. The finding that YM-53601 rapidly decreased plasma cholesterol suggests that this compound may be effective in decreasing plasma cholesterol levels early in the course of treatment of hypercholesterolemia in humans.