In vitro inhibition of human neutrophil histotoxicity by ambroxol: evidence for a multistep mechanism

Baicalin/ambroxol hydrochloride combined dry powder inhalation formulation targeting lung delivery for treatment of idiopathic pulmonary fibrosis: fabrication, characterization, pharmacokinetics, and pharmacodynamics

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and often fatal lung disease caused by multiple factors. Currently, safe, and effective drugs for the treatment of IPF have been extremely scarce. Baicalin (BA) is used to treat pulmonary fibrosis, IPF, chronic obstructive pulmonary disease, and other lung diseases. Ambroxol hydrochloride (AH), a respiratory tract lubricant and expectorant, is often used to treat chronic respiratory diseases, such as bronchial asthma, emphysema, tuberculosis, and cough. The combination of BA and AH can relieve cough and phlegm, improve lung function, and potentially treat IPF and its symptoms. However, given the extremely low solubility of BA, its bioavailability for oral absorptions is also low. AH, on the other hand, has been associated with certain side effects, such as gastrointestinal tract and acute allergic reactions, which limit its applicability. Therefore, an efficient drug delivery system is urgently needed to address the mentioned problems. This study combined BA and AH as model drugs with L-leucine (L-leu) as the excipient to prepare BA/AH dry powder inhalations (BA/AH DPIs) using the co-spray drying method. We the performed modern pharmaceutical evaluation, which includes particle size, differential scanning calorimetry analysis, X-ray diffraction, scanning electron microscope, hygroscopicity, in vitro aerodynamic analysis, pharmacokinetics, and pharmacodynamics. Notably, BA/AH DPIs were found to be advantageous over BA and AH in treating IPF and had better efficacy in improving lung function than did the positive drug pirfenidone. The BA/AH DPI is a promising preparation for the treatment of IPF given its lung targeting, rapid efficacy, and high lung bioavailability.

Drug repositioning in neurodegeneration: An overview of the use of ambroxol in neurodegenerative diseases

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease in adults. While it is primarily characterized by the death of upper and lower motor neurons, there is a significant metabolic component involved in the progression of the disease. Two-thirds of ALS patients have metabolic alterations that are associated with the severity of symptoms. In ALS, as in other neurodegenerative diseases, the metabolism of glycosphingolipids, a class of complex lipids, is strongly dysregulated. We therefore assume that this pathway constitutes an interesting avenue for therapeutic approaches. We have shown that the glucosylceramide degrading enzyme, glucocerebrosidase (GBA) 2 is abnormally increased in the spinal cord of the SOD1^G86R mouse model of ALS. Ambroxol, a chaperone molecule that inhibits GBA2, has been shown to have beneficial effects by slowing the development of the disease in SOD1^G86R mice. Currently used in clinical trials for Parkinson's and Gaucher disease, ambroxol could be considered as a promising therapeutic treatment for ALS.

Ambroxol for the treatment of fibromyalgia: science or fiction?

Fibromyalgia appears to present in subgroups with regard to biological pain induction, with primarily inflammatory, neuropathic/neurodegenerative, sympathetic, oxidative, nitrosative, or muscular factors and/or central sensitization. Recent research has also discussed glial activation or interrupted dopaminergic neurotransmission, as well as increased skin mast cells and mitochondrial dysfunction. Therapy is difficult, and the treatment options used so far mostly just have the potential to address only one of these aspects. As ambroxol addresses all of them in a single substance and furthermore also reduces visceral hypersensitivity, in fibromyalgia existing as irritable bowel syndrome or chronic bladder pain, it should be systematically investigated for this purpose. Encouraged by first clinical observations of two working groups using topical or oral ambroxol for fibromyalgia treatments, the present paper outlines the scientific argument for this approach by looking at each of the aforementioned aspects of this complex disease and summarizes putative modes of action of ambroxol. Nevertheless, at this point the evidence basis for ambroxol is not strong enough for clinical recommendation.

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 in the 21st century: pharmacological and clinical update

BACKGROUND

Belonging to the group of expectorants, ambroxol is an active substance with a long history that influences parameters considered to be the basis for the physiological production and the transport of the bronchial mucus. Therefore, ambroxol's indication is 'secretolytic therapy in acute and chronic bronchopulmonary diseases associated with abnormal mucus secretion and impaired mucus transport'.

OBJECTIVE

The aim of this review is to evaluate the pharmacological and clinical data on the mucokinetic compound ambroxol.

METHODS

The existing database that covers >40 years of pharmacological research and clinical development was analysed. Only studies with adequate study design were evaluated.

CONCLUSION

Ambroxol is shown to exert several activities: i) secretolytic activity (i.e., promotes mucus clearance, facilitates expectoration, and eases productive cough); ii) anti-inflammatory and antioxidant activity; and iii) a local anaesthetic effect through sodium channel blocking at the level of the cell membrane. The reduction on chronic obstructive pulmonary disease exacerbations is consistent and clinically relevant. The anaesthetic effect is a new pharmacological action that could be beneficial in the management of acute respiratory tract infections. The efficacy and safety of ambroxol is well established.

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.

Triptan drugs, natural killer cell cytotoxicity, and neutrophils pro-matrix metalloproteinase-9 secretion

OBJECTIVE

To study the effect of various triptan-like drugs, eg, avitriptan, naratriptan, and sumatriptan, as well as the benzopyran alnitidan, on the natural killer cell (NKC) activity of peripheral blood mononuclear cell (PBMC) samples and highly purified NKC (HPNKC) preparations. We also examined the possible role of these agents as immunomodulators by studying their effect upon the in vitro secretion of pro-matrix metalloproteinase-9 (pMMP-9) from whole blood and purified neutrophils samples.

BACKGROUND

The pharmacological profile of a large number of triptan-like compounds has been extensively studied. However, relatively little is known of their interactions with cellular components of the immune system.

METHODS

Blood was obtained from nonsmoking, drug-free healthy individuals from the Blood Bank of the University of Chile main Clinical Hospital (J.J.A.). PBMC were separated by centrifugation and HPNKC acquired by an immunomagnetic isolation procedure. NKC cytotoxicity was assayed using (51)Cr-labeled K-562 cells as target. Addition of drugs and of effector cells (30 : 1, 50 : 1, and 70 : 1 ratio for PBMCs, and 5 : 1 for HPNKCs) was followed by incubation. Paired Student's t-test (2-tailed) was used to determine the significance of the specific (51)Cr release in controls vs drug-treated samples. Aliquots of whole blood or purified neutrophils were added test drug, incubated, centrifuged, and the supernatant analyzed by gelatine zymography. Gelatinolytic activity was visualized, and a digested zone at MW 92 kD indicated presence of pMMP-9. Area of proteolysis was estimated by densitometry; prestained standards were used to assess pMMP-9 molecular weight.

RESULTS

Peripheral blood mononuclear cell's NKC cytotoxicity was consistently decreased after incubation with each and every one of the drugs tested. This result, observed for the 3 effector : target (E : T) cell ratios used, was relatively similar among the various compounds studied, and reached statistical significance only at E : T 70 : 1. Similar drug treatment failed, however, to produce significant changes in the cytotoxicity of HPNKC preparations, suggesting that modulation of the PBMC's NKC activity and that of HPNKC samples require different kinds of cell's derived signal. Incubation with either of the drugs tested failed to significantly alter (basal) nonstimulated pMPP-9 secretion by whole blood samples. However, basal pMMP-9 secretion by purified neutrophil preparations was significantly inhibited by alnitidan and sumatriptan, and not affected by naratriptan.

CONCLUSIONS

Various drugs with a triptan-like chemical structure interact with cellular components of the innate immune system, resulting in an apparent indirect inhibition of NKC activity and direct inhibition of neutrophils pMMP-9 secretion. These results suggest that they may play a positive role in decreasing the severity of inflammatory processes. Whether this effect is part of triptans antimigraine mechanism of action, or just an added beneficial effect of their use for the reversal treatment of migraine headaches remains to be explored.