Cell-specific modulation of surfactant proteins by ambroxol treatment

Inhibition of TRPA1, Endoplasmic Reticulum Stress, Human Airway Epithelial Cell Damage, and Ectopic MUC5AC Expression by Vasaka (Adhatoda vasica; Malabar Nut) Tea

This study tested whether a medicinal plant, Vasaka, typically consumed as a tea to treat respiratory malaise, could protect airway epithelial cells (AECs) from wood smoke particle-induced damage and prevent pathological mucus production. Wood/biomass smoke is a pneumotoxic air pollutant. Mucus normally protects the airways, but excessive production can obstruct airflow and cause respiratory distress. Vasaka tea pre- and co-treatment dose-dependently inhibited mucin 5AC (MUC5AC) mRNA induction by AECs treated with wood smoke particles. This correlated with transient receptor potential ankyrin-1 (TRPA1) inhibition, an attenuation of endoplasmic reticulum (ER) stress, and AEC damage/death. Induction of mRNA for anterior gradient 2, an ER chaperone/disulfide isomerase required for MUC5AC production, and TRP vanilloid-3, a gene that suppresses ER stress and wood smoke particle-induced cell death, was also attenuated. Variable inhibition of TRPA1, ER stress, and MUC5AC mRNA induction was observed using selected chemicals identified in Vasaka tea including vasicine, vasicinone, apigenin, vitexin, isovitexin, isoorientin, 9-oxoODE, and 9,10-EpOME. Apigenin and 9,10-EpOME were the most cytoprotective and mucosuppressive. Cytochrome P450 1A1 (CYP1A1) mRNA was also induced by Vasaka tea and wood smoke particles. Inhibition of CYP1A1 enhanced ER stress and MUC5AC mRNA expression, suggesting a possible role in producing protective oxylipins in stressed cells. The results provide mechanistic insights and support for the purported benefits of Vasaka tea in treating lung inflammatory conditions, raising the possibility of further development as a preventative and/or restorative therapy.

Repurposing of Chemotherapeutics to Combat COVID-19

Severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) is a novel strain of SARS coronavirus. The COVID-19 disease caused by this virus was declared a pandemic by the World Health Organization (WHO). SARS-CoV-2 mainly spreads through droplets sprayed by coughs or sneezes of the infected to a healthy person within the vicinity of 6 feet. It also spreads through asymptomatic carriers and has negative impact on the global economy, security and lives of people since 2019. Numerous lives have been lost to this viral infection; hence there is an emergency to build up a potent measure to combat SARS-CoV-2. In view of the non-availability of any drugs or vaccines at the time of its eruption, the existing antivirals, antibacterials, antimalarials, mucolytic agents and antipyretic paracetamol were used to treat the COVID-19 patients. Still there are no specific small molecule chemotherapeutics available to combat COVID-19 except for a few vaccines approved for emergency use only. Thus, the repurposing of chemotherapeutics with the potential to treat COVID-19 infected people is being used. The antiviral activity for COVID-19 and biochemical mechanisms of the repurposed drugs are being explored by the biological assay screening and structure-based in silico docking simulations. The present study describes the various US-FDA approved chemotherapeutics repositioned to combat COVID-19 along with their screening for biological activity, pharmacokinetic and pharmacodynamic evaluation.

Ambroxol Treatment Suppresses the Proliferation of Chlamydia pneumoniae in Murine Lungs

Ambroxol (Ax) is used as a mucolytics in the treatment of respiratory tract infections. Ax, at a general dose for humans, does not alter Chlamydia pneumoniae growth in mice. Therefore, we aimed to investigate the potential anti-chlamydial effect of Ax at a concentration four timed higher than that used in human medicine. Mice were infected with C. pneumoniae and 5-mg/kg Ax was administered orally. The number of recoverable C. pneumoniae inclusion-forming units (IFUs) in Ax-treated mice was significantly lower than that in untreated mice. mRNA expression levels of several cytokines, including interleukin 12 (IL-12), IL-23, IL-17F, interferon gamma (IFN-γ), and surfactant protein (SP)-A, increased in infected mice treated with Ax. The IFN-γ protein expression levels were also significantly higher in infected and Ax-treated mice. Furthermore, the in vitro results suggested that the ERK 1/2 activity was decreased, which is essential for the C. pneumoniae replication. SP-A and SP-D treatments significantly decreased the number of viable C. pneumoniae IFUs and significantly increased the attachment of C. pneumoniae to macrophage cells. Based on our results, a dose of 5 mg/kg of Ax exhibited an anti-chlamydial effect in mice, probably an immunomodulating effect, and may be used as supporting drug in respiratory infections caused by C. pneumoniae.

Respiratory RNA Viruses: How to Be Prepared for an Encounter with New Pandemic Virus Strains

The characteristics of the biology of influenza viruses and coronavirus that determine the implementation of the infectious process are presented. With provision for pathogenesis of infection possible effects of serine proteinase inhibitors, heparin, and inhibitors of heparan sulfate receptors in the prevention of cell contamination by viruses are examined. It has been determined that chelators of metals of variable valency and antioxidants should be used for the reduction of replicative activity of viruses and anti-inflammatory therapy. The possibility of a pH-dependent impairment of glycosylation of cellular and viral proteins was traced for chloroquine and its derivatives. The use of low-toxicity drugs as part of adjunct therapy increases the effectiveness of synthetic antiviral drugs and interferons and ensures the safety of baseline therapy.

The past, present and future of RNA respiratory viruses: influenza and coronaviruses

Influenza virus and coronaviruses continue to cause pandemics across the globe. We now have a greater understanding of their functions. Unfortunately, the number of drugs in our armory to defend us against them is inadequate. This may require us to think about what mechanisms to address. Here, we review the biological properties of these viruses, their genetic evolution and antiviral therapies that can be used or have been attempted. We will describe several classes of drugs such as serine protease inhibitors, heparin, heparan sulfate receptor inhibitors, chelating agents, immunomodulators and many others. We also briefly describe some of the drug repurposing efforts that have taken place in an effort to rapidly identify molecules to treat patients with COVID-19. While we put a heavy emphasis on the past and present efforts, we also provide some thoughts about what we need to do to prepare for respiratory viral threats in the future.

Co-aerosolized Pulmonary Surfactant and Ambroxol for COVID-19 ARDS Intervention: What Are We Waiting for?

After more than 225 days of the first reports of the novel coronavirus from China, COVID-19 pandemic is still on surge. The search for an effective and efficient therapeutic and pharmaceutical intervention is as important and urgent now as it was on Day 1. Majority of the efforts in this direction are toward finding small molecule interventions via repurposing or redirecting the therapeutic approaches. This hypothesis proposes a physical intervention approach directed toward rescuing the complex lung pathology observed in COVID-19 related acute respiratory distress syndrome (CARDS). The loss of content as well as the synthesis and turnover of the surfactant in ARDS has been termed as a "collateral damage." A synergistic, early stage, cost-effective, pharmaceutically viable, safe, and immediately available solution is hence required. The effectiveness of exogenous surfactant treatment in ARDS has been marred with several limitations as pointed out in various clinical trials and require revised protocols related to surfactant dose and mode of delivery. This hypothesis proposes aerosolized surfactant delivery taking the optimal dosing and coating costs into account along with co-delivery of ambroxol to provide synergistic benefits. Ambroxol is reported to have anti-inflammatory, -oxidant, -viral, and -bacterial activities and has a direct impact on the production and secretion of the surfactant from the alveolar Type 2 cells. If aerosolized, atomized, or nebulized in the form of ambroxol-loaded phospholipid nanovesicles at the early stages of ARDS, depleted surfactant levels may be reinstated and surfactant turnover can be initiated and maintained. The ability to deliver both the components in aerosolized-nebulized form may have a huge impact on alleviating the healthcare burden in low resource settings where the availability of ventilators is limited. In conclusion, the surfactant-ambroxol co-aerosolized intervention approach hypothesized here has implications reaching to clinical and pharmaceutical translation worldwide.

Potential Anti-COVID-19 Therapeutics that Block the Early Stage of the Viral Life Cycle: Structures, Mechanisms, and Clinical Trials

The ongoing pandemic of coronavirus disease-2019 (COVID-19) is being caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The disease continues to present significant challenges to the health care systems around the world. This is primarily because of the lack of vaccines to protect against the infection and the lack of highly effective therapeutics to prevent and/or treat the illness. Nevertheless, researchers have swiftly responded to the pandemic by advancing old and new potential therapeutics into clinical trials. In this review, we summarize potential anti-COVID-19 therapeutics that block the early stage of the viral life cycle. The review presents the structures, mechanisms, and reported results of clinical trials of potential therapeutics that have been listed in clinicaltrials.gov. Given the fact that some of these therapeutics are multi-acting molecules, other relevant mechanisms will also be described. The reviewed therapeutics include small molecules and macromolecules of sulfated polysaccharides, polypeptides, and monoclonal antibodies. The potential therapeutics target viral and/or host proteins or processes that facilitate the early stage of the viral infection. Frequent targets are the viral spike protein, the host angiotensin converting enzyme 2, the host transmembrane protease serine 2, and clathrin-mediated endocytosis process. Overall, the review aims at presenting update-to-date details, so as to enhance awareness of potential therapeutics, and thus, to catalyze their appropriate use in combating the pandemic.

Safety of ambroxol in the treatment of airway diseases in adult patients

INTRODUCTION

Ambroxol is a widely used secretolytic and mucoactive over-the-counter agent primarily used to treat respiratory diseases associated with viscid mucus. Following post-marketing reports of hypersensitivity reactions and severe cutaneous adverse reactions (SCARs) possibly linked to ambroxol, the European Union's Pharmacovigilance Risk Assessment Committee (PRAC) initiated in April 2014 a review of the safety of ambroxol in all its registered indications, which was finalized in 2016. Areas covered: Here, we evaluate the clinical safety of ambroxol and provide an expert opinion on the benefit-risk balance of ambroxol in the treatment of adult patients with bronchopulmonary diseases. The evidence for this review is derived from clinical trials of ambroxol that were provided to the PRAC by the marketing authorization holders of ambroxol-containing medicines. Expert opinion: Clinical experience accumulated from randomized clinical trials and observational studies suggests that ambroxol is a safe and well-tolerated treatment of bronchopulmonary diseases, with a well-balanced and favorable benefit-risk profile. All reported adverse events were mild and self-limiting, and the risk of SCARs with ambroxol is low. Further investigations could address the safety and efficacy of ambroxol in pediatric lung diseases and in additional therapeutic indications, such as biofilm-dependent airway disease and lysosomal storage disorders.

Effects of the expectorant drug ambroxol hydrochloride on chemically induced lung inflammatory and neoplastic lesions in rodents

Ambroxol hydrochloride (AH) is an expectorant drug used to stimulate pulmonary surfactant and serous airway secretion. Surfactant proteins (SPs) are essential for maintaining respiratory structure and function, although SP expression has also been reported in lung inflammatory and proliferative lesions. To determine whether AH exerts modulatory effects on these lung lesions, we examined its effects on pleural thickening induced by intrathoracic administration of dipotassium titanate (TISMO) in A/JJmsSlc (A/J) mice. We also analyzed the modulatory effects of AH on neoplastic lung lesions induced by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in A/J mice and by N-nitrosobis (2-hydroxypropyl) amine (DHPN) in F344/DuCrlCrj (F344) rats. A/J mice treated with TISMO showed decreased body weight, increased white blood cell (WBC) counts, and pleural thickening caused by pleuritis and poor general condition. However, A/J mice treated with TISMO + 120 ppm showed significant recovery of body weight and WBC counts to the same levels as those of A/J mice not treated with TISMO, although no significant differences were observed in histopathological changes including the immunohistopathological expression of IL-1β in the lung and maximum pleural thickness regardless of AH treatment. In the NNK and DHPN experiments, no significant differences in body weight, hematology, plasma biochemistry, and histopathological changes were associated with AH concentration. These results suggest that AH potentially exerts anti-inflammatory effects but does not have a direct suppressive effect on lung tumorigenesis in rodents.

Suppressive effects of the expectorant drug ambroxol hydrochloride on quartz-induced lung inflammation in F344 rats

Surfactant proteins (SPs) are essential to respiratory structure and function. The expectorant drug ambroxol hydrochloride is clinically prescribed to stimulate pulmonary surfactant and airway serous secretion. Therefore, ambroxol hydrochloride may affect SP production and pulmonary inflammation. Lung toxicity of fine particles of various materials has been examined previously in our in vivo bioassay using the intratracheal (i.t.) instillation approach. In the present study, we evaluated modulatory effects of ambroxol hydrochloride on quartz-induced lung inflammation in F344 rats. Male 6-week-old F344 rats were exposed by i.t. instillation to 2 mg of quartz particles suspended in 0.2 mL of saline. Ambroxol hydrochloride was administered at 0, 12, and 120 ppm in rat basal diet for 28 days, and then formalin-fixed paraffin-embedded lung, liver, and kidney samples were prepared. No changes in general condition, body and organ weights, or food consumption upon exposure to quartz were noted. The mean ambroxol intake in rats of the 12 ppm group was comparable to the human conventional dose. Histopathology of lung lesions was evaluated, and the degree of inflammation was scored. At 120 ppm, ambroxol hydrochloride significantly decreased individual lung inflammation scores for pulmonary edema and lymph follicle proliferation around the bronchiole, as well as the total inflammation score, in quartz-treated rats. Expression of SP-C in the type II alveolar cells and macrophages was greater in inflammatory lesions than in non-inflamed areas. Ambroxol treatment did not affect expression of SP-B and SP-C. In conclusion, we demonstrated that ambroxol hydrochloride relieves quartz-induced lung inflammation.

Immunomodulatory Effects of Ambroxol on Airway Hyperresponsiveness and Inflammation

Ambroxol is used in COPD and asthma to increase mucociliary clearance and regulate surfactant levels, perhaps through anti-oxidant and anti-inflammatory activities. To determine the role and effect of ambroxol in an experimental model of asthma, BALB/c mice were sensitized to ovalbumin (OVA) followed by 3 days of challenge. Airway hyperresponsiveness (AHR), lung cell composition and histology, and cytokine and protein carbonyl levels in bronchoalveolar lavage (BAL) fluid were determined. Ambroxol was administered either before the first OVA challenge or was begun after the last allergen challenge. Cytokine production levels from lung mononuclear cells (Lung MNCs) or alveolar macrophages (AM) were also determined. Administration of ambroxol prior to challenge suppressed AHR, airway eosinophilia, goblet cell metaplasia, and reduced inflammation in subepithelial regions. When given after challenge, AHR was suppressed but without effects on eosinophil numbers. Levels of IL-5 and IL-13 in BAL fluid were decreased when the drug was given prior to challenge; when given after challenge, increased levels of IL-10 and IL-12 were detected. Decreased levels of protein carbonyls were detected in BAL fluid following ambroxol treatment after challenge. In vitro, ambroxol increased levels of IL-10, IFN-γ, and IL-12 from Lung MNCs and AM, whereas IL-4, IL-5, and IL-13 production was not altered. Taken together, ambroxol was effective in preventing AHR and airway inflammation through upregulation of Th1 cytokines and protection from oxidative stress in the airways.

A new role for an old drug: Ambroxol triggers lysosomal exocytosis via pH-dependent Ca²⁺ release from acidic Ca²⁺ stores

Ambroxol (Ax) is a frequently prescribed drug used to facilitate mucociliary clearance, but its mode of action is yet poorly understood. Here we show by X-ray spectroscopy that Ax accumulates in lamellar bodies (LBs), the surfactant storing, secretory lysosomes of type II pneumocytes. Using lyso- and acidotropic substances in combination with fluorescence imaging we confirm that these vesicles belong to the class of acidic Ca(2+) stores. Ax lead to a significant neutralization of LB pH, followed by intracellular Ca(2+) release, and to a dose-dependent surfactant exocytosis. Ax-induced Ca(2+) release was significantly reduced and slowed down by pretreatment of the cells with bafilomycin A1 (Baf A1), an inhibitor of the vesicular H(+) ATPase. These results could be nearly reproduced with NH3/NH4(+). The findings suggest that Ax accumulates within LBs and severely affects their H(+) and Ca(2+) homeostasis. This is further supported by an Ax-induced change of nanostructural assembly of surfactant layers. We conclude that Ax profoundly affects LBs presumably by disordering lipid bilayers and by acting as a weak base. The pH change triggers - at least in part - Ca(2+) release from stores and secretion of surfactant from type II cells. This novel mechanism of Ax as a lysosomal secretagogue may also play a role for its recently discussed use for lysosomal storage and other degenerative diseases.

Ambroxol for women at risk of preterm birth for preventing neonatal respiratory distress syndrome

BACKGROUND

Respiratory distress syndrome (RDS) is caused by a deficiency of pulmonary surfactant (an active agent that keeps pulmonary alveoli open and facilitates the entry of air to the lungs, thus improving the oxygenation of the newborn).A number of interventions such as pulmonary surfactant and prenatal corticosteroids are used to prevent RDS. Ambroxol has been studied as a potential agent to prevent RDS, but effectiveness and safety has yet to be evaluated.

OBJECTIVES

To evaluate the efficacy and safety of giving ambroxol to pregnant women who are at risk of preterm birth, for preventing neonatal RDS.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (29 November 2013), CENTRAL (The Cochrane Library 2013, Issue 11),Embase (1988 to November 2013), MEDLINE (PubMed 1970 to November 2013), LILACS (1982 to November 2013), the WHO International Clinical Trials Registry Platform (ICTRP) (November 2013) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing the administration of ambroxol given to pregnant women at risk of preterm birth versus placebo, antenatal corticosteroids (betamethasone or dexamethasone), or no treatment.We did not identify any trials comparing ambroxol with dexamethasone (corticosteroid) in this review. Nor did we identify any trials comparing ambroxol combined with corticosteroid versus corticosteroid alone, or placebo/no treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and trial quality. Two review authors independently extracted data. Data were checked for accuracy.

MAIN RESULTS

We included 14 studies (in 18 trial reports), involving 1047 pregnant women at risk of preterm birth with 1077 newborns. However, three of the included studies did not report on this review's outcomes of interest. We carried out two main comparisons: ambroxol versus antenatal corticosteroids (betamethasone); and ambroxol versus placebo or no treatment. Seven RCTs provided data for our comparison of ambroxol versus corticosteroid (betamethasone) and two trials contributed data to our comparison of ambroxol compared to placebo or no treatment.The included studies were generally judged as having either 'low' risk of bias or 'unclear' risk of bias (because the trial reports provided insufficient details about methods of sequence generation, allocation concealment and blinding). Primary outcomesThere was no clear evidence of a difference in the incidence of RDS among newborns born to women who received ambroxol when compared to newborns of women who were given the corticosteroid, betamethasone (risk ratio (RR) 0.79, 95% confidence interval (CI) 0.59 to 1.07, seven RCTs, 728 women/758 newborns, moderate quality evidence) or placebo/no treatment (average RR 0.74; 95% CI 0.46 to 1.20, two studies, 204 women/204 newborns,T2= 0.07; I(2)= 53%, low-quality evidence). Results were imprecise and consistent with appreciable benefit as well as negligible effect.Similarly, there was no clear evidence of a difference in the rates of perinatal mortality between the group of women who received ambroxol and women in the corticosteroid (betamethasone) group (RR 0.51, 95% CI 0.23 to 1.12, six studies, 648 women/657 newborns, moderate quality evidence) or the placebo/no treatment group (RR 0.61; 95% CI 0.19 to 1.98, one study, 116 women/116 newborns, low-quality evidence).In terms of maternal adverse effects, there was no clear differences (in nausea or vomiting) between those women who received ambroxol compared to either those women who received corticosteroids (betamethasone) (average RR 3.45; 95% CI 0.34 to 35.51, three studies, 305 women, T(2)= 2.82; I(2)= 67%, very low-quality evidence), or women who received placebo or no treatment (RR 1.79; 95% CI 0.45 to 7.13, one study, 116 women, low-quality evidence). No other adverse effects (e.g. diarrhoea, gastric irritation and headache) were reported in the included studies. Secondary outcomesFor the review's secondary outcomes, none of the included studies reported on the incidence of bronchopulmonary dysplasia, periventricular haemorrhage, necrotising enterocolitis or rate of maternal mortality.One small trial (involving 88 women) comparing ambroxol with placebo or no treatment, reported no difference between groups in terms of the need for mechanical ventilation in the neonate (RR 0.94; 95% CI 0.73 to 1.21, 88 women/88 babies, low-quality evidence) or the administration of pulmonary surfactant (RR 1.19; 95% CI 0.61 to 2.30, one RCT, 88 women/88 babies, low-quality evidence).

AUTHORS' CONCLUSIONS

This review is based on very low to moderate quality evidence from 14 small trials (many are published in the form of conference abstracts with minimal methodological details provided). There is insufficient evidence to support or refute the practice of giving ambroxol to women at risk of preterm birth for preventing neonatal RDS, perinatal mortality and adverse effects. More research is needed in order to fully evaluate the benefits and risks of this intervention.

Biofilm-dependent airway infections: a role for ambroxol?

Biofilms are a key factor in the development of both acute and chronic airway infections. Their relevance is well established in ventilator associated pneumonia, one of the most severe complications in critically ill patients, and in cystic fibrosis, the most common lethal genetic disease in Caucasians. Accumulating evidence suggests that biofilms could have also a role in chronic obstructive pulmonary disease and their involvement in bronchiectasis has been proposed as well. When they grow in biofilms, microorganisms become multidrug-resistant. Therefore the treatment of biofilm-dependent airway infections is problematic. Indeed, it still largely based on measures aiming to prevent the formation of biofilms or remove them once that they are formed. Here we review recent evidence suggesting that the mucokinetic drug ambroxol has specific anti-biofilm properties. We also discuss how additional pharmacological properties of this drug could be beneficial in biofilm-dependent airway infections. Specifically, we review the evidence showing that: 1-ambroxol exerts anti-inflammatory effects by inhibiting at multiple levels the activity of neutrophils, and 2-it improves mucociliary clearance by interfering with the activity of airway epithelium ion channels and transporters including sodium/bicarbonate and sodium/potassium/chloride cotransporters, cystic fibrosis transmembrane conductance regulator and aquaporins. As a whole, the data that we review here suggest that ambroxol could be helpful in biofilm-dependent airway infections. However, considering the limited clinical evidence available up to date, further clinical studies are required to support the use of ambroxol in these diseases.

Ambroxol influences voriconazole resistance of Candida parapsilosis biofilm

The ability to form biofilm on different surfaces is typical of most Candida species. Microscopic structure and genetic aspects of fungal biofilms have been the object of many studies because of very high resistance to antimycotic agents because of the scarce permeability of the external matrix and to the alterations in cell metabolism. In our study, 31 isolates of Candida parapsilosis, isolated from bloodstream infections, were tested for their ability to produce biofilm and were found to be good producers. The susceptibility to voriconazole, assayed by colorimetrical XTT assay, revealed a very elevated minimum inhibitory concentrations for sessile cells in comparison with planktonic ones. The addition of ambroxol, a mucolytic agent, increased the susceptibility of biofilm forming cells to voriconazole. Expression of the efflux pump genes CDR and MDR was analyzed in biofilms alone or treated with ambroxol, evidencing a role of ambroxol in the expression of genes involved in azole resistance mechanisms of C. parapsilosis biofilms. In conclusion, our data seem to encourage the use of different substances in combination with classical antimycotics, with the aim of finding a solution to the increasing problem of the resistance of biofilms formed on medical devices by nonalbicans Candida species.

Ambroxol: a multifaceted molecule with additional therapeutic potentials in respiratory disorders of childhood

INTRODUCTION

Mucoactive drugs are currently used to cleanse the respiratory tract following disturbance of the normal mucociliary clearance due to mucous hyperproduction and/or modification of its physicochemical characteristics. However, in addition to possessing the ability to perform specific actions on airway secretion, these compounds have the capability to modulate the mechanisms involved in abnormal secretions. Indeed, over the years, in the postmarketing phase, a large number of studies have been published showing interesting pharmacological activities in addition to their secretagogue activity.

AREAS COVERED

This article collates available data on ambroxol (2-amino-3,5-dibromo-N-[trans-4-hydroxycyclohexyl]benzylamine), a metabolite of bromhexine, used as a secretagogue in the treatment of childhood airway diseases. This article goes beyond the mucoactive aspects of the drug covering its multiple pharmacological properties.

EXPERT OPINION

The non-mucoactive functions exhibited by the compound may provide beneficial effects on airway structure and function in health and disease. Beyond the mucokinetic and secretagogue effects, ambroxol showed great antioxidant, anti-inflammatory, local anesthetic and surfactant synthesis stimulatory activities. Moreover, some antiviral and antibacterial activities were shown. These findings may better explain the clinical results observed in a variety of airway disorders and suggest additional therapeutic potential. Further studies are needed to better define the clinical relevance of these non-mucolytic activities.

The protective effects of Ambroxol in Pseudomonas aeruginosa-induced pneumonia in rats

INTRODUCTION

To evaluate the effect of Ambroxol on the pulmonary surfactant (PS) in rat pneumonia induced by Pseudomonas aeruginosa (PA).

MATERIAL AND METHODS

The pneumonic rats were obtained by injecting ATCC27853 intratracheally. One hundred and twenty SD rats were randomized into four groups: normal saline and Ambroxol was injected intraperitoneally following PA challenge in the PA/NS and PA/AM group; the other two groups were NS/AM and NS/NS. The wet/dry weight ratio (W/D), and pathological changes were assayed. Total proteins (TP), total phospholipid (TPL), and dipalmitoylphosphatidylcholine (DPPC) in bronchial alveolar lavage fluid (BALF) were analysed. Some BALF was cultured for colony counts. Ultrastructural change of the lung was observed by electron microscopy.

RESULTS

The W/D ratio in the PA/AM group was lower than that in the PA/NS group; both were higher than that in the NS/NS group (p < 0.05). There were more neutrophils in the PA/NS group than in the PA/AM group (p < 0.05), and more in the PA/AM group than in the NS/NS group (p < 0.05). The ratio of DSPC/TPL and DSPC/TP in the BALF in PA/NS group was lower than that in the PA/AM group; DSPC/TPL and DSPC/TP ratios also increased in the NS/AM group. The PA colony numbers in the PA/AM group were lower than in the PA/NS group (p > 0.05). In the PA/NS group, vacuolation occurred in the lamellar body of alveolar type 2 cells (AT2) and the PS layer was rough and broken in some areas. In the PA/AM group, the degree of vacuolation of the lamellar body was less than in the PA/NS group.

CONCLUSIONS

Ambroxol could protect rats from pneumonia by improving the level of endogenous PS, especially DPPC.

Ambroxol: a CNS drug?

For almost three decades ambroxol has been used in the therapy of airway diseases. In 2002, ambroxol lozenges were marketed for the treatment of sore throat making use of its local anesthetic effect. Detailed investigations of ambroxol with modern pharmacological methods yielded additional interesting results: ambroxol has been found to have profound effects on neuronal voltage-gated Na(+), as well as Ca(2+) channels, and to effectively reduce chronic inflammatory and neuropathic pain in rodents. The question was raised whether ambroxol affects the central nervous system (CNS) directly, or whether its effects can be explained solely by a peripheral action. This issue was addressed by re-examining pharmacokinetics, as well as toxicology of ambroxol. It has been concluded that even at the highest clinically used doses ambroxol does not have significant direct effects on the CNS. At clinically relevant plasma concentrations ambroxol either does not penetrate blood-brain barrier, or its brain levels are too low to cause relevant effects. The analgesic effects of ambroxol by either systemic administration to animals, or by topical application in humans can be explained by ambroxol-induced blockade of ion channels in peripheral neurons.