A Novel Ambroxol-Derived Tetrahydroquinazoline with a Potency against SARS-CoV-2 Proteins.

We report synthesis of a novel 1,2,3,4-tetrahydroquinazoline derivative, named 2-(6,8-dibromo-3-(4-hydroxycyclohexyl)-1,2,3,4-tetrahydroquinazolin-2-yl)phenol (1), which was obtained from the hydrochloride of 4-((2-amino-3,5-dibromobenzyl)amino)cyclohexan-1-ol (ambroxol hydrochloride) and salicylaldehyde in EtOH. The resulting compound was produced in the form of colorless crystals of the composition 1∙0.5EtOH. The formation of the single product was confirmed by the IR and 1H spectroscopy, single-crystal and powder X-ray diffraction, and elemental analysis. The molecule of 1 contains a chiral tertiary carbon of the 1,2,3,4-tetrahydropyrimidine fragment and the crystal structure of 1∙0.5EtOH is a racemate. Optical properties of 1∙0.5EtOH were revealed by UV-vis spectroscopy in MeOH and it was established that the compound absorbs exclusively in the UV region up to about 350 nm. 1∙0.5EtOH in MeOH exhibits dual emission and the emission spectra contains bands at about 340 and 446 nm upon excitation at 300 and 360 nm, respectively. The DFT calculations were performed to verify the structure as well as electronic and optical properties of 1. ADMET properties of the R-isomer of 1 were evaluated using the SwissADME, BOILED-Egg, and ProTox-II tools. As evidenced from the blue dot position in the BOILED-Egg plot, both human blood-brain barrier penetration and gastrointestinal absorption properties are positive with the positive PGP effect on the molecule. Molecular docking was applied to examine the influence of the structures of both R-isomer and S-isomer of 1 on a series of the SARS-CoV-2 proteins. According to the docking analysis results, both isomers of 1 were found to be active against all the applied SARS-CoV-2 proteins with the best binding affinities with Papain-like protease (PLpro) and nonstructural protein 3 (Nsp3_range 207-379-AMP). Ligand efficiency scores for both isomers of 1 inside the binding sites of the applied proteins were also revealed and compared with the initial ligands. Molecular dynamics simulations were also applied to evaluate the stability of complexes of both isomers with Papain-like protease (PLpro) and nonstructural protein 3 (Nsp3_range 207-379-AMP). The complex of the S-isomer with Papain-like protease (PLpro) was found to be highly unstable, while the other complexes are stable.

Simultaneous bioanalysis and pharmacokinetic interaction study of acebrophylline, levocetirizine and pranlukast in Sprague-Dawley rats.

The combination of acebrophylline (ABP), levocetirizine (LCZ) and pranlukast (PRN) is used to treat allergic rhinitis, asthma, hay-fever and other conditions where patients experience difficulty in breathing. This study was carried out with the aim of developing and validating a reverse-phase high-performance liquid chromatographic bioanalytical method to simultaneously quantitate ABP, LCZ and PRN in rat plasma. The objective also includes determination of the pharmacokinetic interaction of these three drugs after administration via the oral route after individual and combination treatment in rat. Optimum resolution between the analytes was observed with a C18 Kinetex column (250 mm × 4.6 mm × 5 µm). The chromatography was performed in a gradient elution mode with a 1 mL/min flow rate. The calibration curves were linear over the concentration range of 100-1600 ng/mL. The intra- and inter-day precision and accuracy were found to be within acceptable limits as specified in US Food and Drug Administration guideline for bioanalytical method validation. The analytes were stable on the bench-top (8 h), after three freeze-thaw cycles, in the autosampler (8 h) and as a dry extract (-80°C for 48 h). The statistical results of the pharmacokinetic study in Sprague-Dawley rats showed a significant change in pharmacokinetic parameters for PRN upon co-administration of the three drugs.

Acebrophylline-induced angioedema.

A 53-year-old woman visited her physician complaining of acute breathlessness and productive cough. Her medications included budesonide and formoterol for asthma, fixed-dose combination aspirin 150 mg + clopidogrel 75 mg + atorvastatin 20 mg for ischemic heart disease. History revealed that she had allergic rhinitis and was hypersensitive to penicillins. The patient was prescribed acebrophylline (ABP). Six hours after ABP therapy she presented with generalized urticarial lesions, swelling of hands, feet, lips and face, suggestive of angioedema. ABP was stopped immediately, and the patient was treated symptomatically. This case was categorized as probable as per standard causality assessment scale.

Action of N-acylated ambroxol derivatives on secretion of chloride ions in human airway epithelia.

We report the effects of new N-acylated ambroxol derivatives (TEI-588a, TEI-588b, TEI-589a, TEI-589b, TEI-602a and TEI-602b: a, aromatic amine-acylated derivative; b, aliphatic amine-acylated derivative) induced from ambroxol (a mucolytic agent to treat human lung diseases) on Cl(-) secretion in human submucosal serous Calu-3 cells under a Na(+)/K(+)/2Cl(-) cotransporter-1 (NKCC1)-mediated hyper-secreting condition. TEI-589a, TEI-589b and TEI-602a diminished hyper-secretion of Cl(-) by diminishing the activity of NKCC1 without blockade of apical Cl(-) channel (TEI-589a>TEI-602a>TEI-589b), while any other tested compounds including ambroxol had no effects on Cl(-) secretion. These indicate that the inhibitory action of an aromatic amine-acylated derivative on Cl(-) secretion is stronger that that of an aliphatic amine-acylated derivative, and that 3-(2,5-dimethyl)furoyl group has a strong action in inhibition of Cl(-) secretion than cyclopropanoyl group. We here indicate that TEI-589a, TEI-589b and TEI-602a reduce hyper-secretion to an appropriate level in the airway, providing a possibility that the compound can be an effective drug in airway obstructive diseases including COPD by reducing the airway resistance under a hyper-secreting condition.

Acebrophylline: an airway mucoregulator and anti-inflammatory agent.

Acebrophylline is an airway mucus regulator with antiinflammatory action. The drug's approach involves several points of attack in obstructive airway disease. The molecule contains ambroxol, which facilitates various steps in the biosynthesis of pulmonary surfactant, theophylline-7 acetic acid whose carrier function raises blood levels of ambroxol, thus rapidly and intensely stimulating surfactant production. The resulting reduction in the viscosity and adhesivity of the mucus greatly improves ciliary clearance. By deviating phosphatidylcholine towards surfactant synthesis, making it no longer available for the synthesis of inflammatory mediators such as the leukotrienes, acebrophylline also exerts an inflammatory effect. This is confirmed in vivo by the reduction in aspecific bronchial hyper-responsiveness in patients with stable bronchial asthma. On a clinical level, acebrophylline is therapeutically effective in patients with acute or chronic bronchitis, chronic obstructive or asthma-like bronchitis and recurrence of chronic bronchitis; it reduces the frequency of episodes of bronchial obstruction and reduces the need for beta2-agonists, and improves indexes of ventilatory function.

Action of neltenexine on anion secretion in human airway epithelia.

Neltenexine has been applied to human lung diseases such as chronic obstructive pulmonary disease (COPD) as a mucolytic agent. However, we have no information on the neltenexine action in bronchial epithelial cells. We studied the neltenexine action on the ion transport in human submucosal serous Calu-3 cells. Under a hyper-secreting condition caused by terbutaline (a beta2-adrenergic agonist), neltenexine diminished anion secretion by inhibiting the Cl- and HCO3- uptake via Na+/K+/2Cl- cotransporter and Na+/HCO3- cotransporter without blockade of the cystic fibrosis transmembrane conductance regulator (CFTR) channel, and also diminished anion secretion via stimulation of Cl-/HCO3- exchanger, which facilitates the extrusion of more CFTR-permeant anion, Cl-, with the uptake of less CFTR-permeant anion, HCO3-. Thus, neltenexine reduced the hyper-secretion to keep an appropriate fluid level in the airway, providing a possibility that neltenexine can be an effective drug in airway obstructive diseases by decreasing the airway resistance under a hyper-secreting condition.

Solid-state chemistry of ambroxol theophylline-7-acetate.

Ambroxol theophylline-7-acetate (ACE) is the salt obtained by reaction of equimolar amounts of ambroxol (AMB), a drug showing mucolytic and expectorant properties, and theophylline-7-acetic acid (TAA), a xanthine derivative with specific bronchodilator activity. ACE is used for the treatment of bronchial and pulmonary diseases (bronchitis, asthma, emphysema, chronic obstructive disease). Recrystallization experiments of ACE resulted in the isolation of two polymorphs (monotropically related) and four solvated forms. X-ray diffractometry, DSC, TGA, and HSM techniques were used to investigate the forms that are obtained by thermal desolvation of the solvates. The phase diagram of the TAA-AMB binary system was constructed by performing thermal analyses on mixtures of TAA-AMB and of each component plus the interaction compound (TAA-ACE and ACE-AMB). The Schroeder-Van Laar equation proved to be a very useful tool for checking the consistency between the experimental data and the theoretical model related to the general system, showing complete miscibility in the liquid phase and complete immiscibility in the solid phase.

Oral neltenexine in patients with obstructive airways diseases: an open, randomised, controlled comparison versus sobrerol.

BACKGROUND: The synthetic mucolytic neltene-xine is an amide derivative of ambroxol and thiophencarboxylic acid. The aim of this open, randomised, controlled study versus sobrerol was to evaluate the efficacy and tolerability of neltenexine (oral granules in sachets) as compared with sobrerol (oral granules in sachets), administered to patients with obstructive airways disease. METHODS: Thirty male and female patients were recruited. The exclusion criteria were allergy to neltenexine or sobrerol, an assessed diagnosis of severe bronchospasm requiring beta2-agonists, corticosteroids or aminophylline, pregnant or nursing women, cystic fibrosis, active tuberculosis or an assessed diagnosis of bronchiectasis. No infections of other organs (such as urinary tract infections) were present at baseline. Concomitant treatment with antitussives or other mucolytic agents was not allowed during the course of the study. Fifteen patients were randomised to treatment with neltenexine, 1 sachet thrice daily for 20 days orally (neltenexine group) and 15 patients to treatment with sobrerol, 1 sachet thrice daily for 20 days orally (sobrerol group). The efficacy parameters were: sputum characteristics and volume, difficulty in expectorating, cough, dyspnoea, pulmonary auscultation. Tolerability was monitored and adverse events were reported. RESULTS: The study highlighted that neltenexine has a good efficacy in the treatment of patients with obstructive airways disease entailing significant impairment of clinical parameters. CONCLUSIONS: Neltenexine can be an effective therapeutic alternative to sobrerol.

Neltenexine tablets in smoking and non-smoking patients with COPD. A double-blind, randomised, controlled study versus placebo.

BACKGROUND: The aim of this double-blind, randomised, controlled study vs placebo was to evaluate the efficacy and tolerability of neltenexine (tablets) versus placebo (tablets), administered to smoking and non-smoking patients with chronic obstructive pulmonary disease (COPD). METHODS: Sixty patients with mild stable COPD were recruited. The exclusion criteria were lung cancer, pulmonary tuberculosis, asthma, cystic fibrosis, bronchiectasis, community-acquired pneumonia (CAP), intercurrent infections, concomitant treatment with corticosteroids, antitussives, beta2 agonists, anticholinergic and other mucolytic agents. The patients were allocated randomly to receive neltenexine (20 smokers and 20 non-smokers) or a matching placebo (20 smokers), 1 tablet twice daily for 20 days. The efficacy criteria were sputum characteristics and volume, difficulty in expectorating, cough, dyspnoea, pulmonary auscultation, forced expiratory volume in one second (FEV1), vital capacity and arterial partial oxygen pressure (PO2). Tolerability was monitored and adverse events were reported. RESULTS: At the study end, the improvement of patients treated with neltenexine (smokers and non-smokers) was greater and statistically significant as compared with the patients in the placebo group in terms of improvement of dyspnoea (p<0.02), cough (p<0.02), pulmonary auscultation (p<0.02), and difficulty in expectorating (p<0.02). Furthermore, a significant improvement of the sputum characteristics (p<0.02) and volume (p<0.01) was evidenced, as compared with patients treated with placebo, in non smoking patients treated with neltenexine and in smoking patients treated with neltenexine. CONCLUSIONS: The study confirmed earlier clinical experiences showing that neltenexine is effective in the treatment of COPD patients and highlighted the correlation between abstention from smoking and the efficacy of mucoactive treatment.

Effects of a short course of treatment with acebrophylline on the mucus rheological characteristics and respiratory function parameters in patients suffering from chronic obstructive pulmonary disease.

A total of 30 patients (27 males and 3 females) with a mean age of 62.6 +/- 3.9 years, suffering from chronic obstructive pulmonary disease were recruited into this open study to evaluate the clinical efficacy and the safety of a short course of treatment with 100 mg acebrophylline, twice daily for 14 days. To assess the effectiveness of the drug, symptoms and signs, such as cough intensity and frequency, auscultatory pattern, dyspnoea, cyanosis, difficulty of expectoration, sputum quantity, appearance and density, were evaluated at baseline and after 1, 3, 5, 7, 10 and 14 days of therapy. In addition the rheological properties of the bronchial mucus (viscosity and spinnability) were measured and respiratory function tests were performed before and after treatment. There was a progressive improvement of all evaluated symptoms and signs, resulting in improvement of the auscultatory pattern, as well as dyspnoea. This was accompanied by improvement or normalization of the respiratory function indices, which showed statistically significant differences (P < 0.01) between the baseline and the endpoint values, apart from total lung capacity. Blood-gas analysis demonstrated a significant increase of PaO2 and a significant decrease of PaCO2 values at the end of the treatment period (both P < 0.01). In general, acebrophylline was well tolerated. No clinically relevant or significant changes in any of the routine laboratory parameters were found on comparing the values obtained before and after treatment. Only three patients complained of epigastric pain, but this was not so severe or long-lasting as to require the discontinuation of the treatment.

Neltenexine: morphological investigation of protection against elastase-induced emphysema in rats.

The instillation of elastase into airways is a widely adopted experimental method to quickly produce emphysematous lesions that mimic human disease anatomically and physiologically. Experiments were undertaken to determine whether of not neltenexine, a new drug active on surfactant production, would diminish the severity of this disease. Anaesthetized rats were instilled tracheally with porcine pancreatic elastase (46 U/mg) dissolved in saline, in a single instillation of 0.33 mg/100 microliters. Neltenexine was administered in one experiment at the dose of 25 mg/kg i.p. daily for 30 days. In a second test, neltenexine was given at the same dose six days before the elastase instillation and then by the same schedule as in the first experiment; this was done in search of a possible preventive action. At the end of the treatment, lungs were removed and fixed, and slices were dehydrated, critically point dried, coated with gold and observed by scanning electron microscopy (SEM). Rats that were both pretreated and treated with neltenexine showed a significant reduction in the alveolar deformation induced by elastase. There were no differences between pretreated and treated animals. These experimental findings suggest that neltenexine might prove to be useful for preventing pulmonary emphysema. Biochemical studies in man are needed to confirm the clinical application of neltenexine.

Inhibitory effect of theophylline, theophylline-7-acetic acid, ambroxol and ambroxol-theophylline-7-acetate on rat lung cAMP phosphodiesterase isoenzymes.

It is assumed that theophylline (THEO) and its xanthinic derivatives inhibit lung phosphodiesterase (PDE) and block adenosine receptors in the induction of bronchodilatation. Since the theophyllinic compound ambroxol-theophylline-7-acetic acid (ATA) has been shown in vivo to be a sound bronchodilator, this paper compares the action of ambroxol-theophylline-7-acetate (ATA), its two components, theophylline-7-acetic acid (TAA) and ambroxol (AMB), and theophylline (THEO) on the hydrolytic activity of three rat-lung cAMP PDE (types I, III and IV) and on striatal adenosine receptors. THEO inhibited all three isoenzymes with equal intensity, whereas ATA was as powerful but inhibited types III and IV only, on which AMB and TAA also showed lower effects. Lastly, unlike THEO, ATA and its two components were unable to antagonize adenosine receptors. Taken as a whole, these results suggest that the bronchodilating activity of ATA is the result of specific inhibition of particular forms of PDE and is thus more specific than that of THEO alone.