Interaction of SSR161421, a novel specific adenosine A(3) receptor antagonist with adenosine A(3) receptor agonists both in vitro and in vivo.

A novel adenosine A(3) receptor antagonist (SSR161421) was characterized by both receptor binding assays and pharmacological tests. Binding studies on cloned human adenosine receptors showed that SSR161421 has high affinity for adenosine hA(3) receptors (K(i)=0.37 nM) with at least 1000-fold selectivity compared to hA(1), hA(2A) and hA(2B) receptors. The receptor antagonist nature of SSR161421 was determined in a functional study on Chinese hamster ovarian cells (CHO) cells expressing human adenosine A(3) receptors. SSR161421 competitively antagonized the effect of 2-chloro-N6-(3-iodobenzyl)-adenosine-5'-N-methylcarboxamide (Cl-IB-MECA) on cAMP production with a pA2 value in a luciferase reporter gene construct. In mice, intravenously administered SSR161421 inhibited the N6-(4-aminobenzyl)-adenosine-5'-N-methyl-uronamide dihydrochloride (AB-MECA) induced increase in plasma histamine levels (ED(50)=2.0mg/kg) and the Cl-IB-MECA evoked plasma extravasation (ID(50)=2.9 mg/kg) and oedema formation (ID(50)=4.6 mg/kg) in mouse ear.

SSR240612 [(2R)-2-[((3R)-3-(1,3-benzodioxol-5-yl)-3-[[(6-methoxy-2-naphthyl)sulfonyl]amino]propanoyl)amino]-3-(4-[[2R,6S)-2,6-dimethylpiperidinyl]methyl]phenyl)-N-isopropyl-N-methylpropanamide hydrochloride], a new nonpeptide antagonist of the bradykinin B1 receptor: biochemical and pharmacological characterization.

The biochemical and pharmacological properties of a novel non-peptide antagonist of the bradykinin (BK) B(1) receptor, SSR240612 [(2R)-2-[((3R)-3-(1,3-benzodioxol-5-yl)-3-[[(6-methoxy-2-naphthyl)sulfonyl]amino]propanoyl)amino]-3-(4-[[2R,6S)-2,6-dimethylpiperidinyl]methyl]phenyl)-N-isopropyl-N-methylpropanamide hydrochloride] were evaluated. SSR240612 inhibited the binding of [(3)H]Lys(0)-des-Arg(9)-BK to the B(1) receptor in human fibroblast MRC5 and to recombinant human B(1) receptor expressed in human embryonic kidney cells with inhibition constants (K(i)) of 0.48 and 0.73 nM, respectively. The compound selectivity for B(1) versus B(2) receptors was in the range of 500- to 1000-fold. SSR240612 inhibited Lys(0)-desAr(9)-BK (10 nM)-induced inositol monophosphate formation in human fibroblast MRC5, with an IC(50) of 1.9 nM. It also antagonized des-Arg(9)-BK-induced contractions of isolated rabbit aorta and mesenteric plexus of rat ileum with a pA(2) of 8.9 and 9.4, respectively. Antagonistic properties of SSR240612 were also demonstrated in vivo. SSR240612 inhibited des-Arg(9)-BK-induced paw edema in mice (3 and 10 mg/kg p.o. and 0.3 and 1 mg/kg i.p.). Moreover, SSR240612 reduced capsaicin-induced ear edema in mice (0.3, 3 and 30 mg/kg p.o.) and tissue destruction and neutrophil accumulation in the rat intestine following splanchnic artery occlusion/reperfusion (0.3 mg/kg i.v.). The compound also inhibited thermal hyperalgesia induced by UV irradiation (1 and 3 mg/kg p.o.) and the late phase of nociceptive response to formalin in rats (10 and 30 mg/kg p.o.). Finally, SSR240612 (20 and 30 mg/kg p.o.) prevented neuropathic thermal pain induced by sciatic nerve constriction in the rat. In conclusion, SSR240612 is a new, potent, and orally active specific non-peptide bradykinin B(1) receptor antagonist.

A novel orally active inhibitor of HLE.

Human leukocyte elastase (HLE) is a serine proteinase, capable of degrading a variety of structural matrix proteins. SSR69071 2-[(4-isopropyl-6-methoxy-1,1-dioxido-3-oxo-1,2-benzisothiazol-2(3H)-yl)methoxy]-9-(2-piperidin-1-ylethoxy)-4H-pyrido[1,2-a]pyrimidin-4-one was selected as a novel orally active HLE inhibitor for treatment of chronic obstructive pulmonary diseases, asthma, emphysema, cystic fibrosis and several inflammatory diseases (WO 01/44245 A1) (J. Pharm. Exp. Ther., submitted for publication).

Biochemical and pharmacological characterization of 2-(9-(2-piperidinoethoxy)-4-oxo-4H-pyrido[1,2-a]pyrimidin-2-yloxymethyl)-4-(1-methylethyl)-6-methoxy-1,2-benzisothiazol-3(2H)-one-1,1-dioxide (SSR69071), a novel, orally active elastase inhibitor.

Human leukocyte elastase (HLE) is a proteinase capable of degrading a variety of proteins. Under normal circumstances, the proteolytic activity of HLE is effectively controlled by its natural inhibitors. However, an imbalance between elastase and its endogenous inhibitors may result in several pathophysiological states such as chronic obstructive pulmonary disease, asthma, emphysema, cystic fibrosis, and chronic inflammatory diseases. It is anticipated that an orally active HLE inhibitor could be useful for the treatment of these diseases. 2-(9-(2-Piperidinoethoxy)-4-oxo-4H-pyrido[1,2-a]pyrimidin-2-yloxymethyl)-4-(1-methylethyl)-6-methoxy-1,2-benzisothiazol-3(2H)-one-1,1-dioxide (SSR69071) is a potent inhibitor of HLE, with the inhibition constant (K(i)) and the constant for inactivation process (k(on)) being 0.0168 +/- 0.0014 nM and 0.183 +/- 0.013 10(6)/mol sr, respectively. The dissociation rate constant, k(off), was 3.11 + 0.37 10(-6)/s. SSR69071 displays a higher affinity for human elastase than for rat (K(i) = 3 nM), mouse (K(i) = 1.8 nM), and rabbit (K(i) = 58 nM) elastases. Bronchoalveolar lavage fluid from mice orally treated with SSR69071 inhibits HLE (ex vivo), and in this model, SSR69071 has a dose-dependent efficacy with an ED(50) = 10.5 mg/kg p.o. SSR69071 decreases significantly the acute lung hemorrhage induced by HLE (ED(50) = 2.8 mg/kg p.o.) in mice. Furthermore, SSR69071 prevents carrageenan- (ED(30) = 2.2 mg/kg) and HLE-induced (ED(30) = 2.7 mg/kg) paw edema in rats after p.o. administration. In conclusion, SSR69071 is a selective, orally active, and potent inhibitor of HLE with good penetration in respiratory tissues.