Synthesis and biological properties of novel glucocorticoid androstene C-17 furoate esters.

A series of novel corticosteroid derivatives featuring C-17 furoate ester functionality have been synthesised. Profiling in vitro and in vivo has resulted in the identification of a compound with a longer duration of action and a lower oral side effect profile in rodents compared to budesonide.

New highly potent and selective adenosine A(3) receptor antagonists.

A class of potent, selective adenosine A(3) receptor antagonists was obtained via optimisation of the screening hit N-[4-(4-methoxyphenyl)-thiazol-2-yl]-acetamide. Structural modifications of this hit revealed very quickly that a 5-(pyridin-4-yl) substituent on the 2-aminothiazole ring was optimal for high potency at the adenosine A(3) receptor. Structure activity relationship studies led to both potent and selective A(3) receptor antagonists, including N-[5-pyridin-4-yl-4-(3,4,5-trimethoxyphenyl)-thiazol-2-yl]-acetamide, a highly potent aden-osine A(3) receptor antagonist with greater than 100- fold selectivity against the related adenosine receptors. As well as demonstrating selective in vitro binding on the human A(3) adenosine receptor, this compound was also shown to selectively block the rat A(3) receptor in vivo. This important new compound can be readily synthesised in four steps from commercially available starting materials.

Effects of immunomodulators on airways hyperresponsiveness to adenosine induced in actively sensitised Brown Norway rats by exposure to allergen.

We have recently demonstrated a marked and selective augmentation of the bronchoconstrictor response to adenosine in actively sensitised Brown Norway (BN) rats challenged with ovalbumin (OA). The augmented response is mediated by 5-hydroxytryptamine (5-HT) released as a consequence of mast cell activation. We describe here the effects of budesonide, a clinically used glucocorticosteroid, IMM125, a hydroxyethyl derivative of D-serine-cyclosporine, MLD987, a close analogue of ascomycin and SAR943, a rapamycin derivative, on the hyperresponsiveness to adenosine induced in actively sensitised BN rats by exposure to allergen. Bronchoconstrictor responses to adenosine elicited 3 h following intratracheal (i.t.) instillation of OA, 0.3 mg kg(-1) were reduced dose-dependently by budesonide, IMM125, and MLD987, given i.t. 25 and 1 h prior to allergen challenge. In contrast, SAR943 had no effect on responses to adenosine. Responses to methacholine and 5-HT were minimally affected by these agents. Bronchoconstrictor responses to bradykinin were dose-dependently reduced by budesonide, but unaffected following IMM125, MLD987 or SAR943 pre-treatment. Challenge with OA at a dose of 0.3 mg kg(-1), induced increases in bronchoalveolar lavage (BAL) fluid, leukocyte numbers, eosinophil peroxidase (EPO) and myeloperoxidase (MPO) activities and protein concentration measured 24 h post challenge. Budesonide (1 mg kg(-1) given i.t. 25 and 1 h prior to OA challenge) induced reductions in the BAL fluid parameters of inflammation; IMM125 and MLD987, at a dose of 1 mg kg(-1) had no significant effect whereas SAR943 reduced lymphocyte numbers. Thus, budesonide, IMM125 and MLD987 block the hyperresponsiveness to adenosine induced by allergen challenge in sensitised rats. In the case of budesonide the effect is associated with a powerful, generalised anti-inflammatory effect although an effect directly on the mast cells is also likely. With IMM125 and MLD987, the effect is seen at doses that are not anti-inflammatory and may reflect direct suppression of mast cell activation by these agents.

Effects of CGS 21680, a selective adenosine A2A receptor agonist, on allergic airways inflammation in the rat.

We have investigated the effect of 2(4-((2-carboxymethyl)phenyl)ethylamino)-5'-N-ethylcarboxamidoadenosine (CGS 21680), a potent and selective agonist at adenosine A2A receptors, on pulmonary inflammation induced by allergen challenge in the ovalbumin-sensitised, Brown Norway rat. Aerosol administration of ovalbumin (5 mg x ml(-1) for 60 min; calculated dose 0.4 mg x kg(-1)) induced increases in bronchoalveolar lavage fluid leukocyte numbers, protein content and myeloperoxidase and eosinophil peroxidase activities measured 24 h post challenge. CGS 21680 (10 and 100 microg x kg(-1) given intratracheally (i.t.) 30 min before and 3 h after allergen challenge) inhibited dose-dependently all the parameters of inflammation. Qualitatively similar results were obtained with the glucocorticosteroid, budesonide (0.1, 1 and 10 mg x kg(-1) given 3 h prior to ovalbumin challenge). CGS 21680 given i.t. reduced blood pressure in anaesthetised rats at similar doses to those at which anti-inflammatory effects were manifested. Both the anti-inflammatory and hypotensive responses to CGS 21680 were blocked by pretreatment with the selective adenosine A2A receptor antagonist, 4-(2-(7-amino-2-(2-furyl)(1,2,4)triazolo(2,3-a(1,3,5)triazin-5-yl amino)ethyl)phenol (ZM 241385), 3 mg x kg(-1) p.o., 1 h prior to the agonist. Thus, CGS 21680 manifests broad-spectrum anti-inflammatory activity in a model of allergic asthma in the Brown Norway rat through activation of adenosine A2A receptors. The striking similarity to budesonide, a clinically used anti-inflammatory agent, suggests that adenosine A2A receptor agonists may be useful alternatives to glucocorticosteroids in the treatment of asthma.

KCO912: a potent and selective opener of ATP-dependent potassium (K(ATP)) channels which suppresses airways hyperreactivity at doses devoid of cardiovascular effects.

ATP-sensitive potassium (K(ATP)) channel openers can obviate experimental airways hyperreactivity (AHR) and have shown therapeutic benefit in asthma. However, the clinical potential of such compounds has been compromised by cardiovascular side-effects. We report here the pharmacological properties of (3 S,4 R)-3,4-dihydro-3-hydroxy-2,2-dimethyl-4-(2-oxo-1-piperidinyl)- N-phenyl-2 H-1-benzopyran-6-sulphonamide (KCO912), a K(ATP) channel opener which suppresses AHR at doses devoid of cardiovascular effects.Specific interaction of KCO912 with the native vascular channel and the sulphonylurea receptor subunit (SUR2B) of the vascular K(ATP) channel was shown in radioligand binding assays. In rat aortic strips, KCO912 inhibited specific binding of [3H]P1075 and [3H]glibenclamide with up to 100% efficacy and with p Ki values of 8.28 and 7.96, respectively. In HEK cells transfected with the recombinant vascular K(ATP) channel (Kir6.1 + SUR2B), the compound elicited a concentration-dependent outward current (pEC50 6.8) and in preloaded rat aortic rings it induced a concentration-dependent glibenclamide-sensitive 86Rb+ efflux (pEC50 7.51). Following intratracheal (i.t.) administration of KCO912 to guinea pigs, AHR induced by immune complexes or ozone was rapidly (<5 min) reversed (ED50 values 1 microg/kg and 0.03 microg/kg, respectively). Changes in blood pressure were seen only at doses =100 microg/kg yielding 'therapeutic ratios' of 100 and 3333, respectively. In addition, KCO912 reversed AHR induced by lipopolysaccharide (LPS; ED50 0.5 microg/kg i.t.) and a dose of 1 microg/kg i.t. fully reversed AHR induced by subchronic treatment with salbutamol. At doses which suppressed AHR, KCO912 had no anti-bronchoconstrictor effects in normoreactive guinea pigs. In spontaneously hyperreactive rhesus monkeys, KCO912, given by inhalation, inhibited methacholine-induced bronchoconstriction (ED50 1.2 microg/kg) but had no significant effects on blood pressure or heart rate at all doses tested (therapeutic ratio >100). In rats given 3 mg/kg of KCO912 by inhalation, the ratio of the area under the concentration-time curve (AUC) for lung to the AUC in blood was 190 and the compound was rapidly cleared (initial t1/2 approximately 30 min). Thus, the wide therapeutic window following administration of KCO912 to the lung seems likely to reflect slow or incomplete passage of KCO912 from the lung into the systemic circulation coupled with rapid removal from the systemic circulation.Thus, when given locally to the airways in both guinea pigs and monkeys, KCO912 suppresses AHR at doses devoid of cardiovascular effects and has a significantly better therapeutic window than representative earlier generation K(ATP) channel openers defined in the same models. Given the pivotal role of AHR in the pathophysiology of asthma and the preclinical profile of KCO912, this compound was selected for clinical evaluation.

Pharmacological profile of a novel phosphodiesterase 4 inhibitor, 4-(8-benzo[1,2,5]oxadiazol-5-yl-[1,7]naphthyridin-6-yl)-benzoic acid (NVP-ABE171), a 1,7-naphthyridine derivative, with anti-inflammatory activities.

We investigated the pharmacology of a new class of phosphodiesterase 4 (PDE4) inhibitor, 6,8-disubstituted 1,7-naphthyridines, by using 4-(8-benzo[1,2,5]oxadiazol-5-yl-[1,7]naphthyridin-6-yl)-benzoic acid (NVP-ABE171) as a representative compound and compared its potency with the most advanced PDE4 inhibitor, undergoing clinical trials, Ariflo [cis-4-cyano-4-(3-cyclopentyloxy-4-methoxyphenyl-r-1-cyclohexanecarboxylic acid)]. NVP-ABE171 inhibited the activity of phosphodiesterase 4A, 4B, 4C, and 4D with respective IC(50) values of 602, 34, 1230, and 1.5 nM. Ariflo was about 40 times less potent. In human cells, NVP-ABE171 inhibited the eosinophil and neutrophil oxidative burst, the release of cytokines by T cells, and the tumor necrosis factor-alpha release from monocytes, in the nanomolar range. Ariflo presented a similar inhibition profile but was 7 to 50 times less potent. In BALB/c mice challenged with lipopolysaccharide, NVP-ABE171 inhibited the airway neutrophil influx and activation with an ED(50) in the range of 3 mg/kg. Ariflo was inactive up to a dose of 10 mg/kg. In ovalbumin sensitized Brown Norway rats, NVP-ABE171 inhibited the lipopolysaccharide-induced airway neutrophil influx and activation (ED(50) of 0.2 mg/kg) and the ovalbumin-induced airway eosinophil influx and activation (ED(50) of 0.1 mg/kg). Ariflo was about 100 times less potent in both models. In the ovalbumin model, NVP-ABE171 had a duration of action of more than 24 h. NVP-ABE171 is a novel PDE4 inhibitor that shows activity both in vitro on human inflammatory cells and in vivo in animal models of lung inflammation. This compound class may have potential for the treatment of airway inflammatory conditions such as asthma and chronic obstructive pulmonary diseases.