Teresa Doménech

Characterization of Aclidinium Bromide, a Novel Inhaled Muscarinic Antagonist, with Long Duration of Action and a Favorable Pharmacological Profile

Aclidinium bromide is a novel potent, long-acting inhaled muscarinic antagonist in development for the treatment of chronic obstructive pulmonary disease. Aclidinium showed subnanomolar affinity for the five human muscarinic receptors (M1–M5). [3H]Aclidinium dissociated slightly faster from M2 and M3 receptors than [3H]tiotropium but much more slowly than [3H]ipratropium. Its association rate for the M3 receptor was similar to [3H]ipratropium and 2.6 times faster than [3H]tiotropium. Residence half-life of [3H]aclidinium at the M2 receptor was shorter than at the M3 receptor, demonstrating kinetic selectivity for the M3 receptor. In isolated guinea pig trachea, aclidinium showed comparable potency to ipratropium and tiotropium, faster onset of action than tiotropium, and duration of action similar to tiotropium and significantly longer than ipratropium. Nebulized aclidinium inhibited bronchoconstriction induced by acetylcholine in guinea pigs in a concentration-dependent manner with an onset of action faster than tiotropium. Duration of action of aclidinium (t1/2 = 29 h) was much longer than ipratropium (8 h) but shorter than tiotropium (64 h). In dogs, aclidinium induced a smaller and more transient increase in heart rate than tiotropium at comparable supratherapeutic doses. Therefore, under these conditions, aclidinium showed a greater therapeutic index than tiotropium (4.2 versus 1.6). These results indicate that aclidinium is a potent muscarinic antagonist with a fast onset of action, a long duration of effect, and a favorable cardiovascular safety profile.

Discovery of novel quaternary ammonium derivatives of (3R)-quinuclidinol esters as potent and long-acting muscarinic antagonists with potential for minimal systemic exposure after inhaled administration: identification of (3R)-3-{[hydroxy(di-2-thienyl)acetyl]oxy}-1-(3-phenoxypropyl)-1-azoniabicyclo[2.2.2]octane bromide (aclidinium bromide).

The objective of this work was to discover a novel, long-acting muscarinic M(3) antagonist for the inhaled treatment of chronic obstructive pulmonary disease (COPD), with a potentially improved risk-benefit profile compared with current antimuscarinic agents. A series of novel quaternary ammonium derivatives of (3R)-quinuclidinol esters were synthesized and evaluated. On the basis of its overall profile, (3R)-3-{[hydroxy(di-2-thienyl)acetyl]oxy}-1-(3-phenoxypropyl)-1-azoniabicyclo[2.2.2]octane bromide (aclidinium bromide) emerged as a candidate for once-daily maintenance treatment of COPD. This compound is a potent muscarinic antagonist, with long duration of action in vivo, and was found to have a rapid hydrolysis in human plasma, minimizing the potential to induce class-related systemic side effects. Aclidinium bromide is currently in phase III development for maintenance treatment of patients with COPD.

Phosphodiesterase inhibitory properties of losartan. Design and synthesis of new lead compounds.

A 4-centre PDE4 pharmacophore search has been carried out in several 3D-databases containing compounds belonging to different therapeutic areas. Losartan, an angiotensin-II antagonist, has been identified as a new lead compound for developing PDE4 inhibitors. New families of compounds derived from losartan has been synthesized and their PDE inhibition has been measured.

Characterization of 5-HT receptors on human pulmonary artery and vein : functional and binding studies

1 This study aimed to investigate the 5‐hydroxytryptamine (5‐HT) receptors mediating contraction of ring preparations isolated from human pulmonary arteries and veins. In functional studies, the responses to 5‐HT, sumatriptan, ergotamine, serotonin‐O‐carboxymethyl‐glycyl‐tyrosinamide (SCMGT), α‐methyl 5‐HT (α‐Me) and 2‐methyl 5‐HT (2‐Me) were studied with WAY100635, GR127935, ritanserin, zacopride and SB204070 as antagonists. 2 All agonists produced concentration‐dependent contractions of human pulmonary artery and vein preparations. The order of potency (−log EC50 values) was ergotamine (6.88)>5‐HT (6.41)SCMGT (6.20)=sumatriptan (6.19) α‐Me (6.04) in the artery, and ergotamine (7.84)>5‐HT (6.96)>sumatriptan (6.60)=α‐Me (6.56)>SCMGT (6.09) in the vein. The potency of each agonist, except for SCMGT, was greater in vein than in artery preparations. Contractile responses to 5‐HT were similar in intact and endothelium‐denuded preparations but responses to sumatriptan were enhanced in artery rings without endothelium. 3 GR127935 (1 nM to 0.5 μM) produced an unsurmountable antagonism of the response to 5‐HT, sumatriptan, ergotamine and SCMGT. Ritanserin (1 nM to 1 μM) also reduced the maximum contractile responses to 5‐HT, ergotamine and α‐Me in artery and vein preparations without affecting those to sumatriptan and SCMGT. In endothelium‐denuded preparations, surmountable antagonism of sumatriptan by GR127935 (in the presence of ritanserin) and of α‐Me by ritanserin (in the presence of GR127935) allowed for the calculation of the apparent pKB values of GR127935 (9.17±0.11 in artery and 9.11±0.05 in vein) and ritanserin (8.82±0.09 in artery and 8.98±0.12 in vein). 4 WAY100635 (1 nM to 1 μM), zacopride (1 nM to 1 μM), or SB204070 (1 nM) did not significantly alter the concentration‐response curves for 5‐HT, sumatriptan, ergotamine, SCMGT or 2‐Me in human pulmonary artery or vein thus indicating that 5‐HT1A, 5‐HT3 and 5‐HT4 receptors are presumably not involved in the contractile response to these agonists. 5 Binding studies using selective radioligands for different 5‐HT receptors could not detect the presence of 5‐HT1A receptor binding in human pulmonary blood vessels whereas the 5‐HT1B/1D radioligand [3H]‐5‐CT significantly labelled a population of specific binding sites in both vessel types. The presence of 5‐HT2A receptors could also be inferred from the level of binding of [3H]‐ketanserin to membranes obtained from human pulmonary vessels, although significance could not be reached for arteries. 5‐HT4 specific receptor binding was scarce in veins and absent in the case of arteries. 6 These findings indicate that the human pulmonary artery and vein have a mixed functional population of 5‐HT1B/1D and 5‐HT2A receptors mediating the contractile response to 5‐HT which is consistent with results of the binding studies.

Functional and biochemical evidence for diazepam as a cyclic nucleotide phosphodiesterase type 4 inhibitor

1 The responses of the electrically‐driven right ventricle strip of the guinea‐pig heart to diazepam were recorded in the absence and in the presence of different selective cyclic nucleotide phosphodiesterase (PDE) inhibitors. 2 Diazepam, at concentrations ranging from 1 μM to 100 μM, was devoid of effect on the contractile force in this preparation. 3 Conversely, diazepam (5 μM–100 μM) produced a consistent positive inotropic response in the presence of a concentration (1 μM), that was without effect in the absence of diazepam, of either of the selective PDE 3 inhibitors milrinone or SK&F 94120, but not in the presence of the selective PDE 4 inhibitor rolipram. 4 This effect of diazepam was not γ‐aminobutyric acid (GABA)‐dependent, since it was neither mimicked nor potentiated by GABA, and was not affected by either a high concentration (5 μM) of the antagonists of the benzodiazepine/GABA/channel chloride receptor complex, picrotoxin, flumazenil and β‐carboline‐3‐carboxylic acid methyl ester (βCCMe), or by the inverse agonists, β‐carboline‐3‐carboxylic acid N‐methylamide (βCCMa) and methyl 6,7‐dimethoxy‐4‐ethyl‐β‐carboline‐3‐carboxylate (DMCM, 0.1 μM). Furthermore, a specific antagonist of the peripheral benzodiazepine receptors, PK 11195 (5 μM), did not influence the effect of diazepam. 5 Biochemical studies with isolated PDEs, confirmed that diazepam selectively inhibits type 4 PDE from guinea‐pig right ventricle rather than the other PDEs present in that tissue. The compound inhibited this enzyme in a non‐competitive manner. Diazepam was also able to inhibit PDE 5, the cyclic GMP specific PDE absent from cardiac muscle, with a potency close to that shown for PDE 4. 6 Diazepam displaced the selective type 4 PDE inhibitor, rolipram from its high affinity binding site in rat brain cortex membranes, and also potentiated the rise in cyclic AMP levels induced by isoprenaline in guinea‐pig eosinophils, where only type 4 PDE is present. 7 The PDE inhibitory properties of diazepam were shared, although with lower potency, by other structurally‐related benzodiazepines, that also displaced [3H]‐rolipram from its high affinity binding site. The order of potency found for these compounds in these assays was not related to their potencies as modulators of the GABA receptor through its benzodiazepine binding site. 8 The pharmacological and biochemical data presented in this study indicate that diazepam behaves as a selective type 4 PDE inhibitor in cardiac tissue and this effect seems neither to be mediated by the benzodiazepine/GABA/channel chloride receptor complex nor by peripheral type benzodiazepine receptors.

Pharmacological characterization of almotriptan: an indolic 5-HT receptor agonist for the treatment of migraine

Almotriptan (3-[2-(dimethylamino)ethyl]-5-(pyrrolidin-1-ylsulfonylmethyl )-1H-indo le) has been studied in several models predictive of activity and selectivity at 5-HT receptors. Almotriptan showed low nanomolar affinity for the 5-HT(1B) and 5-HT(1D) receptors in several species, including the human, while affinity for 5-HT receptors other than 5-HT(1B/1D) was clearly less. Affinity for 5-HT(7) and 5-HT(1A) receptors was approximately 40 and 60 times lower than that for 5-HT(1B/1D) receptors, respectively. Almotriptan did not exhibit significant affinity for several non-5-HT receptors studied up to 100 microM. Almotriptan inhibited forskolin-stimulated cyclic AMP accumulation in HeLa cells transfected with 5-HT(1B) or 5-HT(1D) human receptors. In this model, almotriptan had the same efficacy as serotonin and an affinity in the low nanomolar range. It induced vasoconstriction in several vessels in which it was compared with sumatriptan. In isolated dog saphenous veins, almotriptan elicited concentration-dependent contractions with an EC(50) of 394 nM. In both these systems, almotriptan behaved as a full agonist. Infusion of almotriptan into the porcine meningeal vasculature induced vasoconstriction. In contrast, in the pig renal and rabbit mesenteric arteries, it had a very low maximal efficacy even at 100 microM, with similar results obtained in the rabbit renal artery. The results suggest that almotriptan is a potent and selective 5-HT(1B/1D) receptor agonist, with selectivity for the cranial vasculature as compared with peripheral vessels.

Synthesis and biological evaluation of 2,5-dihydropyrazolo[4,3-c]quinolin-3-ones, a novel series of PDE 4 inhibitors with low emetic potential and antiasthmatic properties

A novel series of 2,5-dihydropyrazolo[4,3-c]quinolin-3-ones has been prepared. These compounds showed good PDE 4 inhibitory activity and weak affinity for roliprams binding site. They also exhibited a good anti-inflammatory profile without emetic side effects.

Heterocyclic-fused 3(2H)-pyridazinones as potent and selective PDE IV inhibitors : Further structure-activity relationships and molecular modelling studies

Abstract A novel group of heterocyclic-fused 3(2H)-pyridazinones were synthesized and evaluated as PDE III and PDE IV inhibitors and their affinity for 3 H Rolipram high affinity binding site was determined. The obtained data demonstrated that some of the new compounds are endowed with potent and selective PDE IV inhibitory activity and greatly attenuated affinity for the Rolipram high affinity binding site that seems to be responsible for unwanted effects. Theoretical calculations, performed on representative compounds, demonstrated the presence of three hydrogen-bonding acceptor regions, of which one looks quite different with respect to literature compounds. This finding could explain the different pharmacological profile of the title compounds with respect to the analogs reported in the literature.

Discovery of LAS101057: A Potent, Selective, and Orally Efficacious A2B Adenosine Receptor Antagonist.

The structure-activity relationships for a series of pyrazine-based A2B adenosine receptor antagonists are described. From this work, LAS101057 (17), a potent, selective, and orally efficacious A2B receptor antagonist, was identified as a clinical development candidate. LAS101057 inhibits agonist-induced IL-6 production in human fibroblasts and is active in an ovalbumin (OVA)-sensitized mouse model after oral administration, reducing airway hyperresponsiveness to methacholine, Th2 cytokine production, and OVA-specific IgE levels.

Discovery of N-(5,6-diarylpyridin-2-yl)amide derivatives as potent and selective A(2B) adenosine receptor antagonists.

The synthesis and SAR of a series of N-(5,6-diarylpyridin-2-yl)amide derivatives as potent A(2B) adenosine receptor antagonists is described. Several compounds showed good selectivity versus other adenosine receptors. The potent and selective analogue 9 was shown to have good oral bioavailability in the rat.