Repurposing Melt Degradation for the Evaluation of Mixed Amorphous-Crystalline Blends.

Medicine regulators require the melting points for crystalline drugs, as they are a test for chemical and physical quality. Many drugs, especially salt-forms, suffer concomitant degradation during melting; thus, it would be useful to know if the endotherm associated with melt degradation may be used for characterising the crystallinity of a powder blend. Therefore, the aim of this study was to investigate whether melt-degradation transitions can detect amorphous content in a blend of crystalline and amorphous salbutamol sulphate. Salbutamol sulphate was rendered amorphous by freeze and spray-drying and blended with crystalline drug, forming standards with a range of amorphous content. Crystalline salbutamol sulphate was observed to have a melt-degradation onset of 198.2±0.2°C, while anhydrous amorphous salbutamol sulphate prepared by either method showed similar glass transition temperatures of 119.4±0.7°C combined. Without the energy barrier provided by the ordered crystal lattice, the degradation endotherm for amorphous salbutamol sulphate occurred 50°C below the melting point, with an onset of 143.6±0.2°C. The enthalpies for this degradation transition showed no significant difference between freeze- and spray-dried samples (p>0.05). Distinct from convention, partial integration of the crystalline melt-degradation endotherm was applied to the region 193-221°C which had no contribution from the degradation of amorphous salbutamol sulphate. The linear correlation of these partial areas with amorphous content, R2=0.994, yielded limits of detection and quantification of 0.13% and 0.44% respectively, independent of drying technique. Melt-degradation transitions may be re-purposed for the measurement of amorphous content in powder blends, and they have potential for evaluating disorder more generally.

Synthesis, Purification, and Selective ß2-AR Agonist and Bronchodilatory Effects of Catecholic Tetrahydroisoquinolines from Portulaca oleracea.

A green, biomimetic, phosphate-mediated Pictet-Spengler reaction was used in the synthesis of three catecholic tetrahydroisoquinolines, 1, 2, and 12, present in the medicinal plant Portulaca oleracea, as well as their analogues 3-11, 13, and 14, with dopamine hydrochloride and aldehydes as the substrates. AB-8 macroporous resin column chromatography was applied for purification of the products from the one-step high-efficacy synthesis. It eliminated the difficulties in the isolation of catecholic tetrahydroisoquinolines from the aqueous reaction system and unreacted dopamine hydrochloride. Activity screening in CHO-K1/Gα15 cell models consistently expressing α1B-, ß1-, or ß2-adrenergic receptors indicated that 12 and 2, compounds that are present in P. oleracea, possessed the most potent ß2-adrenergic receptor agonist activity and 2 was a selective ß2-adrenergic receptor agonist at the concentration of 100 µM. Both 12 and 2 exhibited dose-dependent bronchodilator effects on the histamine-induced contraction of isolated guinea-pig tracheal smooth muscle, with EC50 values of 0.8 and 2.8 µM, respectively. These findings explain the scientific rationale of P. oleracea use as an antiasthmatic herb in folk medicine and provide the basis for the discovery of novel antiasthma drugs.

Design and synthesis of 1,2,4-triazolo[1,5-a]pyrimidine derivatives as PDE 4B inhibitors endowed with bronchodilator activity.

A series of 1,2,4-triazolo[1,5-a]pyrimidine derivatives was designed, synthesized, and screened for their phosphodiesterase (PDE 4B) inhibitory activity and bronchodilation ability. Compound 7e showed 41.80% PDE 4B inhibition at 10 µM. Eight compounds were screened for their bronchodilator activity, where compounds 7f and 7e elicited promising bronchodilator activity with EC50 values of 18.6 and 57.1 µM, respectively, compared to theophylline (EC50 = 425 µM). Molecular docking at the PDE 4B active site revealed a binding mode and docking scores comparable to those of a reference ligand, consistent with their PDE 4B inhibition activity.

Discovery of ß-arrestin-biased ß2-adrenoceptor agonists from 2-amino-2-phenylethanol derivatives.

ß-Arrestins are a small family of proteins important for signal transduction at G protein-coupled receptors (GPCRs). ß-Arrestins are involved in the desensitization of GPCRs. Recently, biased ligands possessing different efficacies in activating the G protein- versus the ß-arrestin-dependent signals downstream of a single GPCR have emerged, which can be used to selectively modulate GPCR signal transduction in such a way that desirable signals are enhanced to produce therapeutic effects while undesirable signals of the same GPCR are suppressed to avoid side effects. In the present study, we evaluated agonist bias for compounds developed along a drug discovery project of ß2-adrenoceptor agonists. About 150 compounds, including derivatives of fenoterol, 2-amino-1-phenylethanol and 2-amino-2-phenylethanol, were obtained or synthesized, and initially screened for their ß-adrenoceptor-mediated activities in the guinea pig tracheal smooth muscle relaxation assay or the cardiomyocyte contractility assay. Nineteen bioactive compounds were further assessed using both the HTRF cAMP assay and the PathHunter ß-arrestin assay. Their concentration-response data in stimulating cAMP synthesis and ß-arrestin recruitment were applied to the Black-Leff operational model for ligand bias quantitation. As a result, three compounds (L-2, L-4, and L-12) with the core structure of 5-(1-amino-2-hydroxyethyl)-8-hydroxyquinolin-2(1H)-one were identified as a new series of ß-arrestin-biased ß2-adrenoceptor agonists, whereas salmeterol was found to be Gs-biased. These findings would facilitate the development of novel drugs for the treatment of both heart failure and asthma.

Design, synthesis and biological evaluation of 5-(2-amino-1-hydroxyethyl)-8-hydroxyquinolin-2(1H)-one derivatives as potent ß2-adrenoceptor agonists.

A series of novel ß2-adrenoceptor agonists with a 5-(2-amino-1-hydroxyethyl)-8-hydroxyquinolin-2(1H)-one moiety was designed, synthesized and evaluated for biological activity in human embryonic kidney 293 cells and isolated guinea pig trachea. Compounds 9g and (R)-18c exhibited the most excellent ß2-adrenoceptor agonistic effects and high ß2/ß1-selectivity with EC50 values of 36 pM for 9g and 21 pM for (R)-18c. They produced potent airway smooth muscle relaxant effects with fast onset of action and long duration of action in an in vitro guinea pig trachea model of bronchodilation. These results support further development of the two compounds into drug candidates.

Synthesis & molecular modeling studies of bronchodilatory active indole-pyridine conjugates.

AIM: Synthesis of novel bronchodilatory active indole-pyridine conjugates. Results/methodology: Indole-pyridine conjugates (6a-n, 8a-i and 10a-c) were synthesized in a facile pathway through reaction of 2-[(1-alkyl-1H-indol-3-yl)methylene]malononitriles 4a,b with the corresponding ketone-containing compounds (5a-f, 7a-c and 9a,b) in the presence of sodium alkoxide. Single (6l, 8 g) and powder (6k, 8d) x-ray studies supported the structures. RESULTS: Histamine precontracted isolated tracheal rings of guinea pig exhibited the potent bronchodilation properties of 6c (about double-fold potency relative to the standard reference, theophylline). Some of the synthesized conjugates (8d, 6c, 6f and 6e) revealed promising reduction of IL-8 production during lipopolysaccharide-induced airway inflammatory bioassay. Computational studies (3D pharmacophore, 2D-QSAR 'quantitative structure-activity relationship') showed high approximations to the bronchodilation properties and explained the parameters controlling biological observations.

Synthesis, biological evaluation and molecular modeling of 2-amino-2-phenylethanol derivatives as novel ß2-adrenoceptor agonists.

A novel series of 2-amino-2-phenylethanol derivatives were developed as ß2-adrenoceptor agonists. Among them, 2-amino-3-fluoro-5-(2-hydroxy-1-(isopropylamino)ethyl)benzonitrile (compound 2f) exhibited the highest activity (EC50 = 0.25 nM) in stimulating ß2-adrenoceptor-mediated cellular cAMP production with a 763.6-fold selectivity over the ß1-adrenoceptor. The (S)-isomer of 2f was subsequently found to be 8.5-fold more active than the (R)-isomer. Molecular docking was performed to determine the putative binding modes of this new class of ß2-adrenoceptor agonists. Taken together, these data show that compound 2f is a promising lead compound worthy of further study for the development of ß2-adrenoceptor agonists.

Mesh nebulizers have become the first choice for new nebulized pharmaceutical drug developments.

In the 24 years since first being marketed, the mesh nebulizer has been developed by five main manufacturers into a viable solution for the delivery of high-value nebulized drugs. Mesh nebulizers provide increased portability, convenience and energy efficiency along with similar lung deposition and increased ease of use compared with jet nebulizers. An analysis of EU and US clinical trial databases has shown that mesh nebulizers are now preferred over jet nebulizers for clinical trials sponsored by pharmaceutical companies. The results show a strong preference for the use of mesh nebulizers in trials involving high cost and niche therapy areas. Built-in capability to optimize the way patients use their mesh nebulizer and manage their disease will further increase uptake. [Formula: see text].

Identification of some novel xanthine-based derivatives with bronchodilator activity.

AIM: The discovery of new bronchodilators with higher efficacy than theophylline is an important issue for asthmatic patients. MATERIALS & METHODS: Theophylline 2, 8-bromotheophylline 4 and theobromine 6 were reacted with different 2/3-chloro-N-phenylacetamides 1a-d or their propanamide analogs 1e-g to obtain 3a-g, 5a-g and 7a-g, respectively. The target compounds were screened for their in vitro bronchodilator activity using isolated guinea pig tracheal rings precontracted with histamine and compared with their precursors. RESULTS: Many compounds exhibited promising activity especially 3d, 3f, 5d, 7d and 7e. 2D-QSAR study resulted in a significant model (N = 24, n = 5, R 2 = 0.848, R 2cvOO = 0.748, R 2cvMO = 0.745, F = 21.215, s 2 = 0.0002) using CODESSA-Pro software. CONCLUSION: These compounds can be considered as promising hits for potent bronchodilators that may be useful for further investigations. [Formula: see text].

Synthesis, molecular modeling studies and bronchodilation properties of nicotinonitrile containing-compounds.

Facile synthetic pathway for nicotinonitriles 5a‒o, 7a‒i was demonstrated through reaction of ketones 4a‒k, 6a‒f with ylidenemalononitrile 3 in the presence of sodium alkoxide. Meanwhile, nucleophilic attack of amines on 2-bromonicotinonitrile 9 (obtained through reaction of propenone 8 with malononitrile, followed by bromination with bromine in acetic acid) afforded 3-pyridinecarbonitriles 11a‒d. Single crystal X-ray of compound 7i reveals the monoclinic space group C2/c with 8 molecules per unit cell. Optimized structure of 7i [DFT/B3LYP, 6-31G(d,p)] shows close correlations to that of X-ray study. Compound 5l seems superior among all the synthesized analogues exhibiting bronchodilation properties about three folds potency compared to theophylline (standard reference) through pre-contracted tracheal rings with histamine standard method. Also compound 5a reveals promising observations (about two folds potency of the standard reference). Molecular modeling studies (3D-pharmacophore and 2D-QSAR) supported the observed biological properties.

[ANTIINFLAMMATORY AND REGENERATIVE EFFECT OF PEPTIDE THERAPY IN THE MODEL OF OBSTRUCTIVE LUNG PATHOLOGY].

The effect of the tetrapeptide bronchogen on the structural and functional state of the bronchial epithelium and inflammatory activity in the lungs was studied in the chronic obstructive pulmonary disease (COPD) model, created in rats by a 60-day intermittent exposure to nitrogen dioxide. The cell composition and cytokine-enzyme profile of bronchoalveolar lavage fluid (BALF), the content of secretory immunoglobulin A and surfactant protein B in BALF were determined. Following the course of peptide treatment the decreased activity of neutrophilic inflammation with the normalization of cellular composition and profile of pro-inflammatory cytokines and enzymes in the bronchoalveolar space was observed. The structure of bronchial epithelium, disturbed during formation of COPD model, was restored and accompanied by restoration of its functional activity as evidenced by an increase of secretory immunoglobulin A (local immunity marker) and surfactant protein B, responsible for reducing the alveolar surface tension.

Inhalable Ipratropium Bromide Particle Engineering with Multicriteria Optimization.

Spray-dried ipratropium bromide (IPB) microspheres for oral inhalation were engineered using Quality by Design. The interrogation of material properties, process parameters, and critical product quality attributes interplay enabled rational product design. A 27-3 screening design exhibited the Maillard reaction between L-leucine (LL) and lactose at studied outlet temperatures (OT) >130°C. A response surface custom design was used in conjunction with multicriteria optimization to determine the operating design space to achieve inhalable microparticles. Statistically significant predictive models were developed for volume median diameter (p = 0.0001, adjusted R 2 = 0.9938), span (p = 0.0278, adjusted R 2 = 0.7912), yield (p = 0.0020, adjusted R 2 = 0.9320), and OT (p = 0.0082, adjusted R 2 = 0.8768). An independent verification batch confirmed the model's predictive capability. The prediction and actual values were in good agreement. Particle size and span were 3.32 ± 0.09 µm and 1.71 ± 0.18, which were 4.7 and 5.3% higher than the predicted values. The process yield was 50.3%, compared to the predicted value of 65.3%. The OT was 100°C versus the predicted value of 105°C. The label strength of IPB microparticles was 99.0 to 105.9% w/w suggesting that enrichment occurred during the spray-drying process. The present study can be utilized to initiate the design of the first commercial IPB dry powder inhaler.

Formulation and In Vitro and In Vivo Evaluation of Lipid-Based Terbutaline Sulphate Bi-layer Tablets for Once-Daily Administration.

The objective of this study was to prepare and evaluate terbutaline sulphate (TBS) bi-layer tablets for once-daily administration. The bi-layer tablets consisted of an immediate-release layer and a sustained-release layer containing 5 and 10 mg TBS, respectively. The sustained-release layer was developed by using Compritol®888 ATO, Precirol® ATO 5, stearic acid, and tristearin, separately, as slowly eroding lipid matrices. A full 4 × 2(2) factorial design was employed for optimization of the sustained-release layer and to explore the effect of lipid type (X 1), drug-lipid ratio (X 2), and filler type (X 3) on the percentage drug released at 8, 12, and 24 h (Y 1, Y 2, and Y 3) as dependent variables. Sixteen TBS sustained-release matrices (F1-F16) were prepared by melt solid dispersion method. None of the prepared matrices achieved the targeted release profile. However, F2 that showed a relatively promising drug release was subjected to trial and error optimization for the filler composition to develop two optimized matrices (F17 and F18). F18 which consisted of drug-Compritol®888 ATO at ratio (1:6 w/w) and Avicel PH 101/dibasic calcium phosphate mixture of 2:1 (w/w) was selected as sustained-release layer. TBS bi-layer tablets were evaluated for their physical properties, in vitro drug release, effect of storage on drug content, and in vivo performance in rabbits. The bi-layer tablets showed acceptable physical properties and release characteristics. In vivo absorption in rabbits revealed initial high TBS plasma levels followed by sustained levels over 24 h compared to immediate-release tablets.

Molecular hybridization yields triazole bronchodilators for the treatment of COPD.

A 1,2,4-triazole motif was employed as a bioisostere for the ester commonly used in muscarinic antagonists, and subsequent integrative conjugation to a ß2 agonist quinolinone furnished a new class of bifunctional MABAs for the treatment of COPD. Medicinal chemistry optimization using the principles of 'inhalation by design' furnished a clinical candidate with desirable pharmacological, pharmacokinetic and biopharmaceutical properties.

Continuous and convergent access to vicinyl amino alcohols.

Five active pharmaceutical ingredients (APIs) containing the vicinyl amino alcohol moiety were synthesized using a convergent chemical assembly system. The continuous system is composed of four flow reaction modules: biphasic oxidation, Corey-Chaykovsky epoxidation, phenol alkylation, and epoxide aminolysis. Judicious choice of reagents and module order allowed for two classes of ß-amino alcohols, aryl and aryloxy, to be synthesized in good (27-69%) overall yields.

One-Pot Synthesis of N-Substituted ß-Amino Alcohols from Aldehydes and Isocyanides.

A practical two-stage one-pot synthesis of N-substituted ß-amino alcohols using aldehydes and isocyanides as starting materials has been developed. This method features mild reaction conditions, broad scope, and general tolerance of functional groups. Based on a less common central carbon-carbon bond disconnection, this protocol complements traditional approaches that involve amines and various carbon electrophiles (epoxides, α-halo ketones, ß-halohydrins). Medicinally relevant products can be prepared in a concise and efficient way from simple building blocks, as demonstrated in the synthesis of the antiasthma drug salbutamol. Upgrading the synthesis to an enantioselective variant is also feasible.

Synthesis, bioassay, and QSAR study of bronchodilatory active 4H-pyrano[3,2-c]pyridine-3-carbonitriles.

A statistically significant QSAR model describing the bioactivity of bronchodilatory active 4H-pyrano[3,2-c]pyridine-3-carbonitriles (N = 41, n = 8, R(2) = 0.824, R(2)cv = 0.724, F = 18.749, s(2) = 0.0018) was obtained employing CODESSA-Pro software. The bronchodilatory active 4H-pyrano[3,2-c]pyridine-3-carbonitriles 17-57 were synthesized through a facile approach via reaction of 1-alkyl-4-piperidones 1-4 with ylidenemalononitriles 5-16 in methanol in the presence of sodium. The bronchodilation properties of 17-57 were investigated in vitro using isolated guinea pig tracheal rings pre-contracted with histamine (standard method) and compared with theophylline (standard reference). Most of the compounds synthesized exhibit promising bronchodilation properties especially, compounds 25 and 28.

Novel 8-(p-substituted-phenyl/benzyl)xanthines with selectivity for the A2A adenosine receptor possess bronchospasmolytic activity.

A new series of 8-(p-substituted-phenyl/benzyl)xanthines has been synthesized and evaluated in vitro for adenosine receptor binding affinity and in vivo for bronchospasmolytic effects. It was observed that the nature of substituent at para-position of 8-phenyl/benzyl group on the xanthine scaffold remarkably affects the binding affinity and selectivity of xanthine derivatives for various adenosine receptor subtypes and also their bronchospasmolytic effects. Newly synthesized 8-phenylxanthines displayed potent binding affinity and significant selectivity for A2A receptors and also produced potent bronchospasmolytic effects. Replacement of phenyl ring with benzyl moiety at C8 of xanthine skeleton resulted in notable reduction in adenosine receptor affinity and broncholytic effects.

Novel bronchodilatory quinazolines and quinoxalines: synthesis and biological evaluation.

A series of heterocyclic derivatives analogous to (-)vasicinone, in which the vasicinone C-ring was replaced with alkyl chain terminated by tertiary amine was prepared. N3, C4-O, C4-S or C4-N were used as the sites of attachment. The 4-[3-(1-piperidyl)propylsulfanyl]derivatives displayed bronchodilatory effect at low micromolar concentrations on isolated rat trachea, and low toxicity both on Balb/c 3T3 mouse fibroblast cells and in mice.

Phosphodiesterase inhibitors. Part 5: hybrid PDE3/4 inhibitors as dual bronchorelaxant/anti-inflammatory agents for inhaled administration.

(-)-6-(7-Methoxy-2-(trifluoromethyl)pyrazolo[1,5-a]pyridin-4-yl)-5-methyl-4,5-dihydropyridazin-3(2H)-one (KCA-1490) exhibits moderate dual PDE3/4-inhibitory activity and promises as a combined bronchodilatory/anti-inflammatory agent. N-alkylation of the pyridazinone ring markedly enhances potency against PDE4 but suppresses PDE3 inhibition. Addition of a 6-aryl-4,5-dihydropyridazin-3(2H)-one extension to the N-alkyl group facilitates both enhancement of PDE4-inhibitory activity and restoration of potent PDE3 inhibition. Both dihydropyridazinone rings, in the core and extension, can be replaced by achiral 4,4-dimethylpyrazolone subunits and the core pyrazolopyridine by isosteric bicyclic heteroaromatics. In combination, these modifications afford potent dual PDE3/4 inhibitors that suppress histamine-induced bronchoconstriction in vivo and exhibit promising anti-inflammatory activity via intratracheal administration.