SARS-CoV-2 and SARS-CoV Spike-Mediated Cell-Cell Fusion Differ in Their Requirements for Receptor Expression and Proteolytic Activation

Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) infects cells through interaction of its spike protein (SARS2-S) with angiotensin-converting enzyme 2 (ACE2) and activation by proteases, in particular transmembrane protease serine 2 (TMPRSS2). Viruses can also spread through fusion of infected with uninfected cells. We compared the requirements of ACE2 expression, proteolytic activation, and sensitivity to inhibitors for SARS2-S-mediated and SARS-CoV-S (SARS1-S)-mediated cell-cell fusion. SARS2-S-driven fusion was moderately increased by TMPRSS2 and strongly by ACE2, while SARS1-S-driven fusion was strongly increased by TMPRSS2 and less so by ACE2 expression. In contrast to that of SARS1-S, SARS2-S-mediated cell-cell fusion was efficiently activated by batimastat-sensitive metalloproteases. Mutation of the S1/S2 proteolytic cleavage site reduced effector cell-target cell fusion when ACE2 or TMPRSS2 was limiting and rendered SARS2-S-driven cell-cell fusion more dependent on TMPRSS2. When both ACE2 and TMPRSS2 were abundant, initial target cell-effector cell fusion was unaltered compared to that of wild-type (wt) SARS2-S, but syncytia remained smaller. Mutation of the S2 cleavage (S2') site specifically abrogated activation by TMPRSS2 for both cell-cell fusion and SARS2-S-driven pseudoparticle entry but still allowed for activation by metalloproteases for cell-cell fusion and by cathepsins for particle entry. Finally, we found that the TMPRSS2 inhibitor bromhexine, unlike the inhibitor camostat, was unable to reduce TMPRSS2-activated cell-cell fusion by SARS1-S and SARS2-S. Paradoxically, bromhexine enhanced cell-cell fusion in the presence of TMPRSS2, while its metabolite ambroxol exhibited inhibitory activity under some conditions. On Calu-3 lung cells, ambroxol weakly inhibited SARS2-S-driven lentiviral pseudoparticle entry, and both substances exhibited a dose-dependent trend toward weak inhibition of authentic SARS-CoV-2.IMPORTANCE Cell-cell fusion allows viruses to infect neighboring cells without the need to produce free virus and contributes to tissue damage by creating virus-infected syncytia. Our results demonstrate that the S2' cleavage site is essential for activation by TMPRSS2 and unravel important differences between SARS-CoV and SARS-CoV-2, among those, greater dependence of SARS-CoV-2 on ACE2 expression and activation by metalloproteases for cell-cell fusion. Bromhexine, reportedly an inhibitor of TMPRSS2, is currently being tested in clinical trials against coronavirus disease 2019. Our results indicate that bromhexine enhances fusion under some conditions. We therefore caution against the use of bromhexine in high dosages until its effects on SARS-CoV-2 spike activation are better understood. The related compound ambroxol, which similarly to bromhexine is clinically used as an expectorant, did not exhibit activating effects on cell-cell fusion. Both compounds exhibited weak inhibitory activity against SARS-CoV-2 infection at high concentrations, which might be clinically attainable for ambroxol.

Evaluating the efficacy and safety of bromhexine hydrochloride tablets in treating pediatric COVID-19: A protocol for meta-analysis and systematic review

BACKGROUND

Bromhexine hydrochloride tablets may be effective in the treatment of Coronavirus disease 2019 (COVID-19) in children. This study will further evaluate the efficacy and safety of bromhexine hydrochloride tablets in the treatment of COVID-19 in children.

METHODS

The following electronic databases will be searched, with all relevant randomized controlled trials (RCTs) up to August 2020 to be included: PubMed, Embase, Web of Science, the Cochrane Library, China National Knowledge Infrastructure (CNKI), the Chongqing VIP China Science and Technology Database (VIP), Wanfang, the Technology Periodical Database, and the Chinese Biomedical Literature Database (CBM). As well as the above, Baidu, the International Clinical Trials Registry Platform (ICTRP), Google Scholar, and the Chinese Clinical Trial Registry (ChiCTR) will also be searched to obtain more comprehensive data. Besides, the references of the included literature will also be traced to supplement our search results and to obtain all relevant literature.

RESULTS

This systematic review will evaluate the current status of bromhexine hydrochloride in the treatment of COVID-19 in children, to evaluate its efficacy and safety.

CONCLUSION

This study will provide the latest evidence for evaluating the efficacy and safety of bromhexine hydrochloride in the treatment of COVID-19 in children.

PROSPERO REGISTRATION NUMBER

CRD42020199805.

ETHICS AND DISSEMINATION

The private information of individuals will not be published. This systematic review will also not involve endangering participant rights. Ethical approval is not available. The results may be published in peer-reviewed journals or disseminated at relevant conferences.

Comprehensive analysis of drugs to treat SARS‑CoV‑2 infection: Mechanistic insights into current COVID‑19 therapies (Review)

The major impact produced by the severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) focused many researchers attention to find treatments that can suppress transmission or ameliorate the disease. Despite the very fast and large flow of scientific data on possible treatment solutions, none have yet demonstrated unequivocal clinical utility against coronavirus disease 2019 (COVID‑19). This work represents an exhaustive and critical review of all available data on potential treatments for COVID‑19, highlighting their mechanistic characteristics and the strategy development rationale. Drug repurposing, also known as drug repositioning, and target based methods are the most used strategies to advance therapeutic solutions into clinical practice. Current in silico, in vitro and in vivo evidence regarding proposed treatments are summarized providing strong support for future research efforts.

[Therapeutic modalities for the management of cough associated with acute respiratory viral infection, effective in an otolaryngologist's practice]

The objective of the present study was to evaluate the effectiveness ascoril therapy in comparison with the treatment using the mucoactive agent lasolvan in the adult patients suffering from productive cough associated with acute viral respiratory infection. Patients and methods. The study included 120 patients suffering from productive cough associated with acute viral respiratory infection. They were divided into two groups. The patients comprising group 1 (n=6.) were treated with ascoril, those in group 2 (n=60) were given lasolvan. Results. The effectiveness of the treatment of cough in group 1 was found to be higher compared with that in group 2 (p<0.05); moreover, it was associated with better dynamics of certain indicators of the quality of life, such as the social activity level, vitality, and general health (p<0.05). The safety of the proposed treatment was confirmed by the absence of the adverse events throughout the entire treatment period.

Pharmacokinetic interaction between cefaclor and bromhexine in healthy Chinese volunteers

OBJECTIVE

To determine the pharmacokinetic interaction between cefaclor and bromhexine in healthy Chinese volunteers.

METHODS

Twelve subjects received a cefaclor (CEF) treatment, a bromhexine (BHX) treatment, and a co-treatment of CEF and BHX with a 3 x 3 Latin square design. The wash-out time between periods was 14 days. The plasma and urine drug concentrations of CEF and BHX were detected by HPLC-UV and LC/MS, respectively.

RESULTS

All the 12 volunteers completed the study. There were no significant differences in AUC 0-t and Cmax of CEF in logarithm between the single administration group of CEF and the co-administration group of CEF with BHX. Two one sided t-test showed that CEF was bioequivalent in the 2 groups. There were no significant differences in tmax, MRT, t1/2, and Clr between the 2 groups. Vd/F was significantly lower in the single CEF group than in the co-administration group of CEF and BHX. There were no significant differences of AUC 0-t and Cmax of BHX in logarithm between the single administration group of BHX and the co-administration group of BHX with CEF. Two one sided t-test showed that BHX was bioequivalent in the 2 groups. There were no significant differences in tmax, MRT, t1/2, Vd/F, and Clr between the 2 groups.

CONCLUSION

There is no significant pharmacokinetic parameter change in the drug absorption, metabolism, and excretion, but Vd/F of CEF significant increases in the co-administration of CEF with BHX. The co-administration of CEF and BHX has no adverse drug interaction. The increase of Vd/F may be a favorable drug interaction, which may be the mechanism of the synergistic effect of the 2 drugs.

Kinetics of bromhexine-mediated down-regulation of focal adhesive molecules of uterus and trophectoderm affecting conception in the rat

PURPOSE

Quantitative evaluation of properties of bromhexine (B) for expression of uterine proteins in ovariectomized (OVX) and pregnant rats.

MATERIALS AND METHODS

Expression of proteins through SDS-PAGE, along with incorporation of glycosidic moieties, was conducted in pregnant and OVX rats under B influence. These findings were corroborated with other tests such as implantation sites, fetal and litter sizes in pregnant rats.

RESULTS

In OVX animals, even under the influence of estradiol dipropionate and progesterone, the B recreated a condition akin to OVX animals. It also induced 50-80% inhibition in the incorporation of glycosidic moieties to polypeptide chain. Distinct reduction in implantation sites, fetal sizes and interference in the conception (16/46) in pregnant rats substantiated the results of the action of B as an antiimplantation agent.

CONCLUSION

Bromhexine has shown interference in blastocyst attachment, conception, reduction in number of implantation sites and dwarfing of fetuses; hence, it is a potential candidate for antiimplantation.

Assessment of bromhexine as a treatment regimen in Sjögren's syndrome-like disease in the NOD (non-obese diabetic) mouse

OBJECTIVE

Bromhexine has been reported to alleviate the xerostomia and xerophthalmia associated with secondary Sjögren's syndrome. The aim of this study was to determine if it might prove useful in the treatment of Sjögren's syndrome-like disease of the NOD mouse model for autoimmune sialoadenitis.

METHODS

Groups of mice were divided into sets receiving 60 mg/kg bromhexine in drinking water and control pair-fed animals. The efficacy of drug treatment was assessed by weekly measurement of stimulated saliva volumes, protein concentration, and amylase activity. At termination (20 weeks) submandibular and lacrimal glands were removed to assess the levels of lymphocytic infiltration by histological evaluation under light microscopy.

RESULTS

Control and bromhexine-treated groups of mice showed no difference in the loss or rate of reduction in stimulated saliva flow over the 12 weeks of treatment. No differences were noted in the protein concentration and amylase loss with increasing age of the animals. Similar temporal changes in total protein profiles and aberrant expression of the 20 kDa parotid secretory protein isoform were observed by SDS-polyacrylamide gel profiles and Western bolt analysis. Histological evaluation of exocrine gland sections failed to detect any reduction in focal lymphocyte infiltration.

CONCLUSION

Bromhexine therapy did not alter the development or severity of Sjögren's syndrome-like disease in the NOD mouse model for autoimmune sialoadenitis.

The antioxidative activity of the mucoregulatory agents: ambroxol, bromhexine and N-acetyl-L-cysteine. A pulse radiolysis study

Ambroxol and bromhexine are shown to be scavengers of both superoxide and hydroxyl radicals as determined by pulse radiolysis experiments. The dismutation of superoxide was accelerated 3-fold by bromhexine and 2.5-fold by ambroxol over the rate of spontaneous dismutation. The reaction constants of hydroxyl radicals with bromhexine and ambroxol were determined by competition kinetics to be 1.58 +/- 0.15 x 10(10) M-1S-1 and 1.04 +/- 0.1 x 10(10) M-1S-1, respectively. N-acetyl-L-cysteine also reacted with hydroxyl radicals (1.28 +/- 0.14 x 10(10) M-1S-1) but not with superoxide radical. These effects may be clinically relevant in the treatment of oxidant-associated lung damage induced by inflammatory agents and/or environmental pollutants.

Activity of bromhexine and ambroxol, semi-synthetic derivatives of vasicine from the Indian shrub Adhatoda vasica, against Mycobacterium tuberculosis in vitro

The benzylamines, bromhexine and ambroxol, widely used as mucolytics, have a pH-dependent growth-inhibitory effect on Mycobacterium tuberculosis. As these compounds are concentrated in macrophages, they might exert a clinically useful effect on intracellular tubercle bacilli. This, combined with indirect effects including enhancement of lysozyme levels in bronchial secretions and levels of rifampicin in lung tissue and sputum, and possibly clearance of bacilli-laden mucus from cavities and bronchi, suggests a potentially useful adjunctive function for these agents in the therapy of tuberculosis, and adds credibility to early reports of the beneficial effect of benzylamines in this disease.

Use of ambroxol and bromhexine as mucolytics for enhanced diffusion of furaltadone into tracheobronchial secretions in broilers

1. Ambroxol and bromhexine were evaluated as mucolytics and to enhance the passage of furaltadone into tracheobronchial secretions (TBS) in chronic complicated respiratory disease-affected broilers. 2. Viscosity of TBS was noticeably increased in the ambroxol-treated birds and only slightly increased in the bromhexine groups; however, the physical (nature) of TBS was superior in the ambroxol-treated broilers. 3. There was a clear increase in the passage of furaltadone into tracheobronchial secretions only in the ambroxol-treated birds. 4. Everyday use of ambroxol in broilers is discussed.

[Experimental studies on the influence of selected preparations on secretion of tear fluid. I. Schirmer test I and lysozyme test]

In the paper the influence of ambroxol, betanechol and mesna on the production of tear fluid by the lacrimal gland in rabbits was studied and compared with the effectiveness of bromhexine hydrochloride. Tear secretion was stimulated by the Schirmer I and lysozyme tests. The obtained results indicate that all four examined drugs stimulate the production of tear fluid. The greatest stimulation of secretion was observed after mesna and then after betanechol and ambroxol. The least potent drug was bromhexine.

[Experimental studies on the influence of selected preparations on secretion of tear fluid. II: Light and transmission electron microscopy]

In the paper the influence of ambroxol, bethanechol, mesna and bromhexine hydrochloride on the morphologic appearance of the lacrimal glands in rabbits was studied with the use of light and transmission electron microscopy. The examination of the lacrimal glands in light microscopy has shown in comparison with the control group an increase in the number of secretory granules in rabbit glands after treatment with different drugs. In electron microscopy in animals, after treatment, much more prominent rough endoplasmic reticulum with a considerable distention of the cisternae and increase of the number of secretory granules in the cytoplasm of the cells were seen. The greatest stimulation of the production of tear fluid was observed after treatment with mesna. Nearly similar results were obtained after bethanechol and slightly worse after ambroxol. The least potent drug was bromhexine.

Mucolytic activity of azelastine in mice and rats

The mucolytic activity of azelastine, an antiallergic/antiasthmatic drug, in mice and rats was investigated. The oral administration of test compounds 30 min before phenol red i.p. injection stimulated dye secretion in the trachea of mice. The resulting oral ED50's (mg/kg) were: azelastine, 0.16; salbutamol, 2.5; N-acetylcysteine, 61.8; S-Carboxymethyl-l-cysteine, < 100; bromhexine, > 100; and potassium iodide, approximately 200. In rats, several drugs stimulated secretion of fluorescein sodium (FINa) in the tracheobronchial lumen. The resulting oral ED50's (mg/kg) were: azelastine, 0.33; terbutaline, 0.3; salbutamol, 0.89; and S-carboxymethyl-l-cysteine, 56.8. Terfenadine and diphenhydramine (1-10 mg/kg, p.o.) did not stimulate tracheal secretion in rats and mice. The mucolytic activity of azelastine may contribute to its overall effectiveness, including antitussive activity in asthmatics. Finally, this activity seems to be dissociated from its H1-histamine receptor blocking activity.

Bromhexine plus oxytetracycline: the effect of combined administration upon the rheological properties of mucus from the mini-pig

Three adult mini-pigs were employed to assess the effects of a twice daily dosage (40 mg kg-1) of oxytetracycline hydrochloride (OTC) and a combination of OTC with (0.5 mg kg-1) bromhexine hydrochloride (BHC) on the rheological properties and wet weight of secreted tracheal mucus. Mucus was collected daily from open-ended tracheal pouches established surgically in the mini-pigs. After a five day control period, either OTC or OTC plus BHC was administered twice daily with the normal diet. Each study period was followed by a five day washout period when mucus was collected but no drug given. The viscoelastic properties of each mucus sample were determined using creep compliance analysis. OTC was shown to increase the residual shear viscosity IP < 0.01) and increase the instantaneous compliance (P < 0.01). An increase in the wet weight of the collected mucus occurred in one pig only (P < 0.01). When BHC was co-administered with OTC, all of these changes were abolished. Evidence was obtained to suggest that BHC increased the concentration of OTC within the secreted mucus. BHC appeared to reverse the mucospissic activity of OTC in-vivo.

Lacrimal secretion stimulants: sigma receptors and drug implications

3H-DTG (1.3-di(2-[5-3H]tolyl)guanidine) or 3H-haloperidol was added to sigma-receptors (25 nM) in the presence of 25 nM spiperone and incubated with increasing concentrations of bromhexine derivatives (phenylalkylamines; 10(-9) to 10(-2)M) in membrane homogenate suspensions. IC50 values for two derivatives ranged from 3.2 to 8.8 nM for both radioligands. A preferred derivative, 7A (N,N'-dimethyl-2-phenyl-ethylamine), yielded an IC50 of 7.8 nM for 3H-haloperidol but showed much less affinity in displacing 3H-DTG (IC50 = 900 nM). Applying the technic of Bromberg [Exp. Eye Res., 40:313-320, 1985], in vitro protein secretion rates were measured following stimulation of either lacrimal gland slices or isolated, intact lacrimocytes with the compounds. In vitro protein secretion rates exhibit a dose-response relationship with increases in protein release up to a concentration of 10(-8) to 10(-4) M for various derivatives of bromhexine and 10(-4) M for carbachol. By means of Schirmer strips, tear fluid was collected over a five minute period at 10 and 60 minutes post-dosing following the topical application (50 microliters) to the right eye of New Zealand white rabbits (n = 20-24) of 7A at various concentrations. Incubation of lacrimocytes with 7A alone (10(-4) M), with haloperidol (10(-4) M) alone or in combination show that 7A is acting as an agonist to stimulate protein release, whereas haloperidol is acting as an antagonist to inhibit release. In vivo protein secretion rates also show a dose-response curve (at both 10 and 60 minutes post-dosing) for 7A that reach a statistically significant maximum in the dosed eye at a concentration of 0.15% w/v. Analysis of protein extracts using size exclusion HPLC shows an increase in secretory proteins, particularly tear-specific prealbumin.

Clinical observations with Paxirasol aerosol in patients suffering from chronic bronchitis accompanying silicosis

Paxirasol aerosol applied in daily 3 x 5 puff doses in the treatment of silicosis patients is found to be a well tolerated drug form. In the course of the 21-day therapy especially coughing and chest pain were moderated, but the product also controlled, the catarrhal coat formation on the mucosa. It influenced abundant expectoration and dispnoea beneficially. During the therapy the laboratory parameters did not change. The objective respiratory parameters improved but the change was non-significant. Paxirasol aerosol is found useful in the treatment of chronic bronchitis accompanying silicosis. Evaluable side-effects were not registered.

Percutaneous absorption of bromhexine in rats

The percutaneous absorption of bromhexine (BH), an expectorant drug, through rat skin was examined in vitro and in vivo. BH in free base form penetrated better than the hydrochloride through the skin. When the in vitro penetration of BH was compared using Plastibase, macrogol and sucrose ester of fatty acid F-160 (DK-ester) formulations, the DK-ester formulation showed the best penetration of BH of the three. The addition of Azone (3%) or lauric acid (BH: lauric acid molar ratio, 1:1) considerably increased BH penetration to a relatively large penetration rate. The plasma levels of BH after in vivo application of the DK-ester formulation with Azone or lauric acid (0.6 g/3.8 cm2) were also higher than those after the formulation without an enhancer, and a constant plasma level (20-50 ng/ml) was obtained during the application for 48 h. However, the bioavailability was low, 2.5 and 2.7% respectively. When the amount of BH remaining in DK-ester ointment and the skin after an 18-h application was measured, the BH content in the ointment was 88.6 +/- 8.0% for the formulation without Azone and 93.7 +/- 6.9% for that with Azone. The low penetration and low bioavailability observed will thus be due to the high drug retention of the base.

[Experimental investigations on the influence of bromhexine hydrochloride on the excretion of lacrimal fluid]

The influence of bromhexine hydrochloride on the excretion of the lacrimal fluid in rabbits was investigated by means of lysozyme test. The investigations showed that the application of the compound is leading to a considerable increase of excretion of tears. It reaches its maximum after ca. 2 hours from the moment of application when the production of tears is ca. 80 p.c. larger than before it. This suggests the possibility of application of bromhexine hydrochloride in the therapy of keratoconjunctivitis sicca.

The effect of bromhexine hydrochloride on the viscoelastic properties of mucus from the mini-pig

Mucus was collected daily from open-ended pouches established surgically in three mini-pigs. After a five day control period bromhexine hydrochloride (BHCl) was administered to each pig at dose levels of 0.5, 1.0 and 2.0 mg.kg-1 twice daily for five days. Each study period was followed by a five day washout period, when mucus was collected but no drug given. The viscoelastic properties of each mucus sample were determined using creep compliance analysis. BHCl was shown to reduce the residual shear viscosity (p less than 0.05) and increase the instantaneous shear compliance at all dose levels (p less than 0.005), despite the large inherent intra- and inter-animal variation in the rheological properties of the daily samples. No change was found in the wet weight of the mucus samples throughout any of the study periods. This experimental model would appear to provide a valuable in vivo method of assessing the mucoregulatory potential of administered compounds.

[Effects of inhaled bromhexine on the bronchomotor tone in rats and guinea pigs]

Bromhexine has been widely used as a mucolytic expectorant. Clinically, bromhexine is sometimes administered by inhalation. However, the effect of bromhexine by inhalation on bronchial musculature has not been documented. In the present study, the effect of inhaled bromhexine on bronchomotor tone in rats and guinea pigs was investigated. The bronchomotor tone was measured by a modified Konzett-Rössler method, and ventilation overflow (VO) was continuously recorded as an index of airway resistance. In rats, inhalation of bromhexine (0.1% and 0.2%, pH 5.3) caused no change in VO. At 0.2%, bromhexine slightly decreased systemic blood pressure (BP). In guinea pigs, bromhexine had no significant effect on VO at 0.2%, and it produced a significant but very slight increase at 0.1%. BP was slightly decreased by inhalation of bromhexine (0.1% and 0.2%, pH 5.3). N-Acetyl-L-cysteine, a cysteine-mucolytic (20%, pH 6.8), had no effect on VO and BP in either species. Inhalation of 0.1% bromhexine solution at pH 2.5, which was dissolved in tartaric acid solution, significantly increased VO, because of its acidity. From the above results, it is suggested that when the pH of the solution is considered, bromhexine has no or almost negligible effect on airway smooth muscles, and it may be useful as an effective mucolytic.

Effect of bromhexine on nasal mucus clearance in chronic maxillary sinusitis

Nasal mucus clearance (NMC) was studied in seventy patients with chronic maxillary sinusitis. Forty-five patients were treated with oral administration of bromhexine tablets along with oral antibiotics and nasal decongestants. Twenty-five patients received the same treatment but without bromhexine to evaluate the results. NMC was also studied in hundred healthy controls.

The effects of bromhexine hydrochloride and S-carboxymethyl-L-cysteine on guinea-pig uterine microflora

This study used guinea-pigs as a mammalian model to investigate the effects of bromhexine hydrochloride and S-carboxymethyl-L-cysteine on the integrity of the cervical mucus plug. It was shown that under normal circumstances the uterus is sterile, but following drug administration microorganisms began to appear in the uterus with no significant effect on the vaginal microbial population. It therefore appears that these two mucolytic agents may reduce cervical mucus viscoelasticity. After the animals had been mated, microorganisms were isolated from the uterus even in the absence of drug treatment.

Deposition and clearance of monodisperse aerosols in the calf lung: effects of particle size and a mucolytic agent (bromhexine)

Mucociliary clearance and retention of monodisperse aerosols of radiolabelled polystyrene particles of both 3.3 microns and 5 microns diameter were investigated in four healthy calves and two sick calves. The effect of the mucolytic agent bromhexine was also assessed at two dosage levels. There were significant differences (P less than 0.05) in clearance rate constant between calves, but similar patterns of clearance for each calf. These characteristics of mechanical lung clearance did not vary over a two month period. Values of clearance rate constant and percentage retention varied significantly (P less than 0.001) between the two different particle sizes, 5 microns particles giving faster clearance and lower retention of particles than 3.3 microns particles. Bromhexine at the recommended dose of 1.6 mg/kg 0.75 caused a significant (P less than 0.05) increase in clearance rate in both healthy and sick calves, but affected percentage retention only in sick calves. This study illustrates the variation in mucociliary clearance rates shown by individuals and also underlines the importance of particle size in aerosols used for studies of pulmonary deposition and clearance. The work also indicates that bromhexine may be of use in the therapy of respiratory disease in calves.

[The effect of ambroxol and bromhexine on the "respiratory burst" of alveolar macrophages]

The effect of ambroxol and bromhexine on the yeast cell wall- and arachidonic acid (AA)-induced luminol-respectively lucigenin-dependent chemiluminescence (CL) of alveolar macrophages (AM) of patients with lung diseases has been investigated. Both drugs cause a suppression of the induced CL. These results suggest that ambroxol and bromhexine reduce the generation of reactive oxygen metabolites (ROM) by AM. The mechanism of action is thought to involve the activation of the acyl-CoA: lysophosphatide acyltransferase. The increase of this enzyme activity lowers probably the intracellular concentration of free AA and consequently also the production of ROM. The investigations show a new possibility for the influence of biosynthesis of ROM and likely of eicosanoids, which play an important role as pathogenetic mediators in different lung diseases.

Estimation of a drug effect by a simplified radioaerosol inhalation lung cine-scintigraphy: bromhexine on mucociliary clearance mechanisms

A proposed simplification of radioaerosol inhalation lung cine-scintigraphy, namely 60 min measurement of radioactivity without repeating measurement at 24 hr later and calculation of alveolar deposition ratio (ALDR) by the regression formula of ALDR = -48.08 + 0.47 X FEV1.0% + 0.59 X LRR60, was found useful and applicable even to the evaluation of a drug on mucociliary clearance mechanisms. The simplified method indicated a very similar evaluation of the effect of bromhexine on airway clearance efficiency with those actually revealed by the original method.

Effects of bromhexine on the secretions of saliva and tears

Effects of bromhexine and pilocarpine on the secretions of submaxillary saliva in dogs and of tears in rabbits were investigated including their effects on lysozyme activity in an attempt to elucidate the efficacy of bromhexine on Sjögren's syndrome. Pilocarpine (0.3 mg/kg, p.o.) significantly increased spontaneous salivary flow rate, but bromhexine (20 and 40 mg/kg, p.o.) had almost no influence on spontaneous salivary flow rate. Pilocarpine increased total protein, saccharide, lysozyme and IgA secretions in saliva under electrical stimulation of the chorda tympani. Bromhexine did more markedly increase total lysozyme and IgA secretions in saliva, with minor increases in total protein and saccharide secretions. Pilocarpine (0.4 mg/kg, i.v.) had almost no influence on lysozyme concentration in tears, whereas it markedly increased tear secretion volume leading to an increase in total lysozyme secretion. On the other hand, bromhexine (4 and 8 mg/kg, i.v.) significantly increased both lysozyme concentration and total lysozyme secretion in tears from 50 min after injection, without influencing tear secretion volume. From these findings, it is suggested that bromhexine may work effectively on Sjögren's syndrome by acting to accelerate the secretions of lysozyme and IgA in saliva and tears, which are known to have antiinflammatory and bacteriocidal effects.

Drugs affecting clearance of middle ear secretions: a perspective for the management of otitis media with effusion

Otitis media with effusion (OME) is characterized by the production and accumulation in the middle ear of mucus secretions, whose physicochemical properties are an important feature in the etiology and treatment of the disease. Many types of pharmaceutical agents, including anti-inflammatory agents, antihistamines, antibiotics, and mucolytics, have been used in attempts to improve the clinical status of patients with OME. This study critically reviews the literature from the point of view of possible changes induced by these agents in the physicochemical properties of the secretions and hence their clearance from the middle ear. In vitro studies on mucociliary clearance of respiratory (tracheobronchial) secretions and middle ear effusions are cited as the basis for analyzing the important parameters expected to govern middle ear clearance and to determine the rationale for use (or nonuse) of various classes of drugs. It is expected that this analysis will prove useful in the design of properly controlled trials of such agents.

Ultrastructural changes of the pulmonary parenchyma after experimentally induced endotoxic shock in dogs with and without drug protection

The authors describe the ultrastructural alterations of the pulmonary parenchyma produced in dogs by endotoxic shock, and they examine the effects that a 'secretolytic' drug (bromexine) has in modifying those changes. In the animals under shock there is a complete breakdown of the normal structure of the pulmonary parenchyma. According to the authors, these lesions are caused by the damage of the lining layer and of the cells which produce the constituents of the surfactant system. In dogs under shock and treated with bromexine the authors have seen a better organization of the pulmonary parenchyma: the cellular limits of the pneumocytes of types I and II were more clearly defined and the osmiophilic bodies were increased both in number and volume. The authors conclude that the damage of the lining layer and of the pneumocytes of type II plays an important role in the development of the ARDS and they say that bromexine can improve clinical and morphological aspects of that syndrome.

Mucolytic agents and mucociliary activity

The three substances bromhexine, NA 872 (bromhexine metabolite VIII) and the beta 2-receptor agonist NAB 365 (clenbuterol) and their effect on the mucociliary activity have been studied in vivo in rabbits. The substances were given parenterally in increasing dosages and 519 records were obtained from 12 rabbits. Not even at dosages in excess of recommended human dosages has any effect on the mucociliary activity been observed for any of the substances during the first 30 minutes after administration. The conclusion to be drawn is that the three substances have no effect on the mucociliary activity in rabbit in vivo, but that this does not exclude an effect on mucociliary transport or clearance.

[Changes in secretory activity of tracheal submucosal glands by repeated treatment with brovanexine and BR-227 in rats]

The effects of brovanexine (BvX) and BR-227 on sectetory activities of tracheal submucosal glands (SG) including behavior of mucus glycoproteins in the cells were investigated. BvX, BR-227 or bromhexine (BH) was given repeatedly at a dose of 10 or 20 mg/kg p.o. a day, to rats for 1, 3, 7 or 14 days. Then, the trachea was excised and drug effects were determined according to our histological/histochemical technique. The outer diameter of the acini of SG did not change, but the inner diameter markedly increased by the drug given for 3-14 days. The ratio of the acinar inner diameter to the tracheal wall thickness (AIWR) was increased with the 3, 7, and 14 day treatments with BvX or BR-227 at a dose of 10 mg/kg a day. On the other hand, these drugs at a dose of 20 mg/kg a day caused an increase in AIWR when drug was given for 1-14 days. BH (10 mg/kg a day)-induced increase in AIWR was shown when drug was administered for 7 and 14 days. The number of SG cells stained blue with alcian blue (pH 2.5)/periodic acid-Schiff decreased with the 1, 3, 7 and 14 day treatments, and a part of SG cells became red with the 7- and 14-day treatments. There was no significant difference in the effects among the three drugs both qualitatively and quantitatively. These findings indicate that repeated treatments with BvX and BR-227 have an effective secretagogic action on SG, and in addition, a mucolytic action toward acid glycoprotein in granules of the cells.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of vagal reflex in mechanism of secretagogic action of bromhexine

The in vivo effect of bromhexine on secretory activities of tracheal submucosal glands was investigated with a histological/histochemical technique with reference to a role of the vagal reflex. When bromhexine was given at 5, 10 or 20 mg/kg into the stomach of anesthetized dogs, the ratio of acinar inner diameter of the submucosal gland to wall thickness (AIWR) markedly increased in a biphasic manner; the early transient increase was seen 0.5 hr after administration, and the second prolonged increased occurred during 2 to 6 hr after administration. The early stimulant phase was almost abolished by atropine, 1 mg/kg i.v., or bilateral cervical vagotomy, whereas the second stimulant phase was not affected by these treatments. Emetine also induced a similar early increase in AIWR at 0.5 hr after administration, the change also being abolished by atropine or surgical vagotomy in this case. The number of submucosal glandular cells which stained blue and purple with a combination of alcian blue at pH 2.5 and periodic acid-Schiff was decreased by bromhexine, but the cell number which stained red was markedly increased. These histochemical changes in glandular cells were not influenced by treatment with atropine or surgical vagotomy. In the present study, it was found that bromhexine exerts both a secretagogic action on submucosal glands and a mucolytic action toward acid glycoproteins inside the cells in vivo. Also, the secretagogic action of bromhexine occurs biphasically; the first phase results from the vagal reflex probably through a gastrointestinal irritation, and the second phase results from a direct action on the glands.

[Pharmacological effects of brovanexine hydrochloride (BR-222) on the respiratory tract system, particularly on the respiratory tract fluid, mucociliary transport and cough]

Pharmacological effects of brovanexine hydrochloride (BR-222), a new expectorant, on the respiratory tract system was studied in comparison with that of bromhexine hydrochloride. 1. When doses ranging from 5 to 40 mg/kg of BR-222 were given orally (p.o.) or intraduodenally (i.d.) to rats, rabbits and dogs, it caused a significant increase in the output volume of respiratory tract fluid (RTF). It was almost as potent as bromhexine, but its pattern of increasing RTF was different from that of bromhexine. The increase in the serous ingredient of RTF after BR-222 administration seemed to be more remarkable than that after bromhexine treatment, though both drugs had no influences on the component ratio of glucose or protein in the RTF of dogs. 2. BR-222 at 10 and 20 mg/kg (i.d.) showed a tendency to reduce the viscosity of RTF in anesthetized dogs and so did bromhexine. A dose of 10 mg/kg (i.d.) of BR-222 also showed a tendency to reduce the viscosity of sputum obtained from the SO2-exposed rabbits. 3. A dose of 6 mg/kg (i.m.) of BR-222 caused a significant increase in the mucociliary transport rate in unanesthetized pigeons; in contrast with this, bromhexine caused a slight decrease. 4. Both drugs given orally showed no antitussive effects when examined by the "coughing dog" method.

Effect of expectorants on relaxation behavior of sputum viscoelasticity in vivo

We studied the effects of expectorants (mucolytic agents) in vivo on the relaxation behavior of sputum viscoelasticity. Seven female and thirty-three male patients (56.8 +/- 19.3 yrs, range: 21 to 82 years old) with a chronic pulmonary disease except bronchial asthma were studied. They were randomly put into the control group or a group which would be given oral treatments with an expectorant for a week after a one week washout period. The groups were as follows: Group I (n = 8), control; Group II (n = 7), Bromhexine hydrochloride 24 mg per day; Group III (n = 10), Ambroxol 90 mg per day; Group IV (n = 9) alpha - Chymotrypsin buccle 100 ch.u. per day; Group V (n = 6), Serratiopeptidase 30 mg per day. In Groups IV & V, frequency dependence of sputum viscoelasticity at the range of omega = 10(-3) to 10(0) rad.sec-1 were clearly changed after the treatments, and the magnitude of the relaxation and its main relaxation time were significantly increased. On the other hand, in Groups I, II & III, no significant changes of the frequency dependences were observed. These findings suggest that proteolytic enzymes administered orally work on the molecular structure of sputum, and break down their linkages between subunits of the structure.

[Sequential changes of the activities of the dog tracheal secretory cells caused by intraduodenal application of brovanexine]

The effects of brovanexine (BvX) on secretory activities of tracheal secretory cells and on behavior of mucus glycoprotein in these cells were investigated histologically and histochemically using the biopsy technique. When BvX was given at 10 or 20 mg/kg intraduodenally to anesthetized dogs, the thickness of the acini of submucosal glands (SG) and the ratio of the acinar inner diameter to the tracheal wall thickness (A1WR) markedly increased dose-dependently after 2 to 6 hr. The numbers of goblet cells (GC) and glandular cells showing a stain index B&P with a combination of alcian blue (AB) at pH 2.5 or pH 1.0 and periodic acid-Schiff (PAS) were reduced dose-dependently after 1 to 6 hr, while the number of cells with a stain index R were increased. Both the BvX-induced histological changes in SG and histochemical changes in GC and SG reached a peak after 4 hr. These histological and histochemical changes were also found for the BR-227-, a metabolite of BvX, and bromhexine (BH)-treated groups. BR-227- or BH-induced histological changes were to the same degree as those induced by BvX, but BvX- or BR-227-induced histochemical changes were slighter than those induced by BH. The total number of GC stained positively with a combination of AB at pH 2.5 and PAS was unaffected by BvX or BH treatment, while BR-227 tended to decrease it. These findings suggest that BvX both has a secretagogic action selectively on SG and a mucolytic action toward acid glycoprotein in granules of secretory cells in vivo, and these actions are durable.

Effect of BR-227, a new bromhexine derivative, on secretory activities of tracheal secretory cells

The effects of BR-227 on secretory activities of canine tracheal secretory cells including behavior of mucus glycoproteins were investigated histologically and histochemically. Following BR-227 treatment at a concentration of alcian blue at pH 2.5 and periodic acid-Schiff (AB (pH 2.5)/PAS) decreased in a concentration-dependent manner. Furthermore, a decrease in the thickness of the acini of submucosal glands and in marked increase in the ratio of acinar inner diameter of the gland to tracheal wall were induced after application of BR-227 at a concentration range of 10(-7) to 10(-4) M. The numbers of goblet and submucosal glandular cells which stained blue and purple with AB (pH 2.5)/PAS were decreased by BR-227 treatment in a concentrations-dependent way, whereas the cells which stained red were markedly increased. In the experiment using a combination of AB at pH 1.0 and PAS, a decrease in sulfated glycoproteins in those secretory cells was observed. Total saccharide and protein concentrations in the incubation fluid increased with BR-227 treatment, while N-acetylhexomsamine concentration tended to decrease. These findings suggest that BR-227 stimulates secretory activities of both goblet cells and submucosal glands, and lowers mucus viscosity in the secretory cells.

A role of lysosomal enzymes in the mechanism of mucolytic action of bromhexine

The effect of bromhexine on behaviors of lysosomal enzymes in the submucosal gland was investigated using canine tracheal slice preparations, with reference to the histochemical changes in acid glycoproteins (AGP) in the gland. Incubation of tracheal slices with 1% Triton X-100 or 0.0004-0.04% bromhexine for 30 min decreased the number of stained lysosomes in the glandular cells. The decrease in stained lysosomes after treatment with 1% Triton X-100 or 0.04% bromhexine was effectively prevented by addition of 5% lecithin. The number of glandular cells that were stained red (stain index R) in the combined alcian blue at pH 2.5 and periodic acid-Schiff procedure markedly increased by treatment with 1% Triton X-100 or 0.0004-0.04% bromhexine. In the bromhexine treated groups, there was a close correlation (r=0.932, P less than 0.01) between the increase in the number of glandular cells showing the stain index R and the decrease in the number of stained lysosomes in the cells. These findings suggest that the enzymes which are liberated from lysosomes into the cytoplasm by bromhexine may, at least in a part, be involved in the mucolytic action of the agent on AGP contained in mucus granules of the submucosal gland.

[Comparative study of tracheal organ cultures obtained from different bird donors]

Comparative studies were carried out on the quality (duration, intensity, and extent) of the cliliary activity in tracheal cultures from chick embryos, chickens, and pheasants. It was found that all cultures had long life, however, they were shown to differ essentially by the function of the tracheal epithelium. In tracheal cultures from pheasants the ciliary activity remained unchanged at the initial level for 70 days. In those from-day-old chicks it remained for 15 days, and cultures from 20-day-old chick embryos showed activity for 25 days. In the second and third type of tracheal cultures the ciliary activity gradually dropped by intensity and scope down to nil within the periods of time mentioned. The ciliary activity of tracheal segments cultured in tubes of a roller apparatus persisted for a considerably longer period than that of segments stationary cultured in petri dishes. The same result was obtained when the explanted trachea was treated with a mycolytic agent (bromhexinehydrochloride), although cultivation was carried out in petri dishes. The high quality (intensity and scope) and duration (70 days) of the ciliary activity of tracheal cultures from pheasants provides an excellent system for the study of the ciliostatic effect on different viruses.

Effects of expectorants on the canine tracheal ciliated cells

Many expectorants are clinically effective as they reduce viscosity and facilitate expectoration. There are, however, few reports on effects of expectorants on tracheal ciliated cells. We investigated the effects of N-acetylcysteine, ethylcysteine and bromhexine on the ciliary activities of the canine trachea. Ciliary movement was estimated using a phototransistor, and intracellular electrical activity was measured with a microelectrode method, in vitro. N-Acetylcysteine, ethylcysteine and bromhexine in low concentrations under a low perfusion rate (0.1 ml/min) produced an increase in the amplitude and frequency of ciliary beating, while N-acetylcysteine and ethylcysteine caused a cilio-depression in high concentration. N-Acetylcysteine, ethylcysteine and bromhexine, under a low perfusion rate, did not affect the intracellular electrical activity. On the other hand, these three drugs under a high perfusion rate (1 ml/min) produced no change in the ciliary movement and the intracellular electrical activity in concentrations of 10(-8)-10(-4) M. These results suggest that the increase in ciliary activity produced by the mucolytic drugs is not due to a direct effect on the ciliated cells, but rather to a mucolytic effect on the mucus around the cilia.

[Effect of bromhexine on the tracheal secretory cells with enhanced mucus synthesis by pilocarpine treatment (author's transl)]

The effects of bromhexine on secretory activities of canine tracheal secretory cells with stimulated synthesis of acid glycoprotein (AGP) by pilocarpine 10(-6)M treatment an on behaviour of glycoprotein in these secretory cells were investigated histologically and histochemically. Following bromhexine treatment, the number of total glycoprotein-containing goblet cells (GC) remained unchanged. The numbers of AGP-containing and sulphated glycoprotein (SGP)-containing GC significantly decreased, while neutral glycoprotein (NGP)-containing GC significantly increased. The acinar inner diameter of the submucosal gland and the acinar inner diameter of this gland to wall ratio slightly increased. Thickness of the acinus and Reid index slightly decreased, concentration-dependently. AGP and SGP content in glandular cells decreased, while NGP content in these cells markedly increased. Bromhexine 10(-5) and 10(-4)M treatment resulted in increased total saccharide and protein concentrations in the incubation fluid, whereas the agent significantly decreased N-acetylhexosamine, in a concentration-dependent manner. These findings suggest that while bromhexine does not stimulate secretory activities of GC, it does slightly stimulate the activities of the submucosal glands. Bromhexine markedly dissolves AGP in the granules of these secretory cells.

[Histological and histochemical changes of tracheal secretory cells following bromhexine treatment (author's transl)]

The effects of bromhexine, a mucolytic agent, on secretory activities of canine tracheal secretory cells and on behaviour of glycoprotein in these secretory cells were investigated histologically and histochemically. Following bromhexine treatment, the number of total glycoprotein-containing goblet cells (GC) remained the same. The number of acid glycoprotein (AGP)-containing GC was reduced concentration-dependently, while neutral glycoprotein (NGP)-containing GC significantly increased with doses of 10-6, 10-5 and 10-4M. The number of sulphated glycoprotein (SGP) in AGP-containing GC decreased concentration-dependently. Acinar inner diameter of the submucosal gland and an acinar inner diameter of this gland to wall ratio (AIWR) increased with doses of 10-5 and 10-4M. Particularly, AIWR significantly increased with dose of 10-4M. Thickness of the acinus tended to slightly decrease concentration-dependently. AGP content in glandular cells decreased, while NGP content in these cells markedly increased, concentration-dependently. SGP content in the glandular cells decreased. Total saccharide and protein concentrations in the incubation fluid significantly increased with higher concentrations of the treatment, whereas N-acetylhexosamine slightly decreased concentration-dependently. These findings suggest that bromhexine does not enhance secretory activities of GC, but does stimulate the activities of the submucosal glands, when the drug is given in higher concentrations. Bromhexine markedly dissolves AGP in granules of the secretory cells.