Hamish Ryder

Reversal of P-glycoprotein mediated multidrug resistance by novel anthranilamide derivatives

We have synthesised and evaluated a series of anthranilamide based modulators of P-glycoprotein. These studies have identified XR9576(2), a potent inhibitor of P-glycoprotein in vitro and in vivo. The general synthesis and the SAR of these compounds are described.

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.

Pharmacological Characterization of Abediterol, a Novel Inhaled β2-Adrenoceptor Agonist with Long Duration of Action and a Favorable Safety Profile in Preclinical Models

Abediterol is a novel potent, long-acting inhaled β2-adrenoceptor agonist in development for the treatment of asthma and chronic obstructive pulmonary disease. Abediterol shows subnanomolar affinity for the human β2-adrenoceptor and a functional selectivity over β1-adrenoceptors higher than that of formoterol and indacaterol in both a cellular model with overexpressed human receptors and isolated guinea pig tissue. Abediterol is a full agonist at the human β2-adrenoceptor (Emax = 91 ± 5% of the maximal effect of isoprenaline). The potency and onset of action that abediterol shows in isolated human bronchi (EC50 = 1.9 ± 0.4 nM; t½ onset = 7–10 min) is not significantly different from that of formoterol, but its duration of action (t½ ∼ 690 min) is similar to that of indacaterol. Nebulized abediterol inhibits acetylcholine-induced bronchoconstriction in guinea pigs in a concentration-dependent manner, with higher potency and longer duration of action (t½ = 36 h) than salmeterol (t½ = 6 h) and formoterol (t½ = 4 h) and similar duration of action to indacaterol up to 48 h. In dogs, the bronchoprotective effect of abediterol is more sustained than that of salmeterol and indacaterol at doses without effects on heart rate, thus showing a greater safety margin (defined as the ratio of dose increasing heart rate by 5% and dose inhibiting bronchospasm by 50%) than salmeterol, formoterol, and indacaterol (5.6 versus 3.3, 2.2, and 0.3, respectively). In conclusion, our results suggest that abediterol has a preclinical profile for once-daily dosing in humans together with a fast onset of action and a favorable cardiovascular safety profile.

Studies on Quinazolinones as Dual Inhibitors of Pgp and MRP1 in Multidrug Resistance

The syntheses and SAR studies of various quinazolinone compounds are described for the dual inhibition of Pgp and MRP1 in multidrug resistance.

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.

Solid-phase synthesis of 4-aminopiperidine analogues using the Alloc protecting group: an investigation of Alloc removal from secondary amines

Abstract A useful method for Alloc removal from secondary amines on solid-phase has been optimised. The use of Me 2 NH·BH 3 (40 equiv., 40 min) as scavenger of the allyl cations in a palladium-catalysed process with Pd[PPh 3 ] 4 leads to quantitative removal of the Alloc group without any allyl back alkylation. Other scavengers such as morpholine or PhSiH 3 are clearly inferior. Furthermore, this study has highlighted differences in the reaction kinetics of the deprotection step between secondary and primary amines such as those from α-amino acids.

Synthesis and biological activity of 1-alkylcarbonylmethyl analogues of YM022

Abstract A novel series of 1-alkylcarbonylmethyl analogues of the potent gastrin/CCK-B receptor antagonist YM022 have been prepared. A number of analogues retained good affinity for the gastrin/CCK-B receptor and one compound (6d) showed improved binding and enhanced selectivity for this receptor over CCK-A. A second compound (6j) gave improved in vivo inhibition of gastric acid secretion in rats. Both analogues were shown to have significantly better activity in the same model following i.d. dosing than either YM022 or L-365,260.

Synthesis and Evaluation of Some Pyrazolo[3,4-d]pyridazinones and Analogues as PDE 5 Inhibitors Potentially Useful as Peripheral Vasodilator Agents

A series of pyrazolo[3,4-d]pyridazinones and analogues, potentially useful as peripheral vasodilators, were synthesized and evaluated as inhibitors of PDE5 extracted from human platelets. Several of them showed IC 50 values in the range 0.14-1.4 μM. A good activity and selectivity profile versus PDE6 was found for compound 11e (6-benzyl-3-methyl-1-isopropyl-4-phenylpyrazolo[3,4-d]pyridazin-7(6H)-one). Structure-activity relationship studies demonstrated the essential role played by the benzyl group at position-6 of the pyrazolopyridazine system. Other types of pyridazinones fused with five and six membered heterocycles (pyrrole, isoxazole, pyridine and dihydropyridine), as well as some open models were prepared and evaluated. Besides the pyrazole, the best fused systems proved to be isoxazole and pyridine.

Design of a Biased Potent Small Molecule Inhibitor of the Bromodomain and PHD Finger-Containing (BRPF) Proteins Suitable for Cellular and in Vivo Studies.

The BRPF (bromodomain and PHD finger-containing) family are scaffolding proteins important for the recruitment of histone acetyltransferases of the MYST family to chromatin. Evaluation of the BRPF family as a potential drug target is at an early stage although there is an emerging understanding of a role in acute myeloid leukemia (AML). We report the optimization of fragment hit 5b to 13-d as a biased, potent inhibitor of the BRD of the BRPFs with excellent selectivity over nonclass IV BRD proteins. Evaluation of 13-d in a panel of cancer cell lines showed a selective inhibition of proliferation of a subset of AML lines. Pharmacokinetic studies established that 13-d had properties compatible with oral dosing in mouse models of disease (Fpo 49%). We propose that NI-42 (13-d) is a new chemical probe for the BRPFs suitable for cellular and in vivo studies to explore the fundamental biology of these proteins.