Benzalkonium chloride and nasal mucociliary clearance: a randomized, placebo-controlled, crossover, double-blind trial

Evaluation of Recent Intranasal Drug Delivery Systems to the Central Nervous System

Neurological diseases continue to increase in prevalence worldwide. Combined with the lack of modifiable risk factors or strongly efficacious therapies, these disorders pose a significant and growing burden on healthcare systems and societies. The development of neuroprotective or curative therapies is limited by a variety of factors, but none more than the highly selective blood-brain barrier. Intranasal administration can bypass this barrier completely and allow direct access to brain tissues, enabling a large number of potential new therapies ranging from bioactive peptides to stem cells. Current research indicates that merely administering simple solutions is inefficient and may limit therapeutic success. While many therapies can be delivered to some degree without carrier molecules or significant modification, a growing body of research has indicated several methods of improving the safety and efficacy of this administration route, such as nasal permeability enhancers, gelling agents, or nanocarrier formulations. This review shall discuss promising delivery systems and their role in expanding the clinical efficacy of this novel administration route. Optimization of intranasal administration will be crucial as novel therapies continue to be studied in clinical trials and approved to meet the growing demand for the treatment of patients with neurological diseases.

The effect of ingredients commonly used in nasal and inhaled solutions on the secretion of mucus in vitro

Hypersecretion of mucus is associated with impaired mucociliary clearance that can influence the retention of active pharmaceutical ingredients in the airway but is also linked with recurrent airway disease. Therefore, the effect on mucin secretion of a range of ingredients used in solutions delivered to the nose and lung was studied. Mucin secretion from explants of ovine epithelium was quantified using an enzyme-linked lectin assay (ELLA) or sandwich ELLA depending on the compatibility of the ingredients with the assay. Benzalkonium chloride (0.015% w/w), Methocel™ E50 premium LV (1.0% w/w), propylene glycol (1.5% w/w), potassium sorbate + propylene glycol (0.3% w/w + 1.5% w/w) and polysorbate 80 (0.025% w/w), used at common working concentrations, all increased the secretion of mucin from the explants (P < 0.05). Ethylenediamine tetraacetic acid-disodium salt (EDTA) (0.015% w/w), Avicel® RC591 (1.5% w/w), fluticasone furoate (0.0004% w/w, concentration in solution) and dimethyl sulfoxide (DMSO) (0.2% w/w) did not affect mucin secretion. Compounds increasing mucin secretion could alter the rate of mucociliary clearance and the mucus could provide a barrier to drug absorption. This could predispose patients to disease and affect the activity of delivered drugs, decreasing or increasing their clinical efficacy.

Neutralization of the eye and skin irritant benzalkonium chloride using UVC radiation

PURPOSE

Benzalkonium chloride (BAK) is a widely used disinfectant and preservative which is effective against a wide range of viruses (e.g. SARS-CoV and SARS-CoV-2), bacteria and fungi. However, it is toxic to the eye and skin. This study investigated the neutralization of BAK using ultraviolet C (UVC) radiation as an effort to reduce BAK toxicity potential.

METHODS

BAK solutions were irradiated with a germicidal UVC lamp at various doses. Human corneal epithelial cells (HCEC) were then exposed to the UVC-irradiated BAK solutions for 5 minutes. After exposure, the cultures were assessed for metabolic activity using PrestoBlue; for cell viability using confocal microscopy with viability dyes; and for tight junction proteins using immunofluorescence staining for zonula occludens (ZO)-1.

RESULTS

UVC radiation reduced BAK toxicity on cell metabolic activity in a dose-dependent manner. When the solution depth of BAK was 1.7 mm, the UVC doses needed to completely neutralize the toxicity of BAK 0.005% and 0.01% were 2.093 J/cm² and 8.374 J/cm², respectively. The cultures treated with UVC-neutralized BAK showed similar cell metabolic activity and cell viability to those treated with phosphate buffered saline (PBS) (p = 0.806 ∼ 1.000). The expression of ZO-1 was greatly disturbed by untreated BAK; in contrast, ZO-1 proteins were well maintained after exposure to UVC-neutralized BAK.

CONCLUSIONS

Our study demonstrates that the cell toxicity of BAK can be neutralized by UVC radiation, which provides a unique way of detoxifying BAK residues. This finding may be of great value in utilizing the antimicrobial efficacy of BAK (e.g. fighting against SARS-CoV-2) while minimizing its potential hazards to human health and the environment.

Assessment of respiratory and systemic toxicity of Benzalkonium chloride following a 14-day inhalation study in rats

Background

Although biocides at low concentrations have been used to control pests, they can be more harmful than industrial chemicals as humans are directly and frequently exposed to such biocides. Benzalkonium chloride (BAC or BKC) is a non-toxic substance used to control pests. Recently, BAC has been increasingly used as a component in humidifier disinfectants in Korea, raising a serious health concern. Moreover, it poses significant health hazards to workers handling the chemical because of direct exposure. In the present study, we aimed to evaluate the respiratory toxicity of BAC due to its inhalation at exposure concentrations of 0.8 (T1 group), 4 (T2 group) and 20 (T3 group) mg/m³.

Results

In our previous study on the acute inhalational toxicity of BAC, bleeding from the nasal cavity was observed in all the rats after exposure to 50 mg/m³ BAC. Therefore, in this study, 20 mg/m³ was set as the highest exposure concentration, followed by 4 and 0.8 mg/m³ as the medium and low concentrations for 6 h/day and 14 days, respectively. After exposure, recovery periods of 2 and 4 weeks were provided. Additionally, alveolar lavage fluid was analyzed in males of the BAC-exposed groups at the end of exposure and 2 weeks after exposure to evaluate oxidative damage.

In the T3 group exposed to BAC, deep breathing, hoarseness, and nasal discharge were observed along with a decline in feed intake and body weight, and nasal discharge was also observed in the T1 and T2 groups. ROS/RNS, IL-1β, IL-6, and MIP-2 levels decreased in a concentration-dependent manner in the bronchoalveolar lavage fluid. Histopathological examination showed cellular changes in the nasal cavity and the lungs of the TI, T2, and T3 groups.

Conclusions

As a result, it was confirmed that the target organs in the respiratory system were the nasal cavity and the lungs. The adverse effects were evaluated as reversible responses to oxidative damage. Furthermore, the no observed adverse effect level was found to be less than 0.8 mg/m³ and the lowest benchmark dose was 0.0031 mg/m³. Accordingly, the derived no-effect level of BAC was calculated as 0.000062 mg/m³.

Inhalation toxicity of benzalkonium chloride and triethylene glycol mixture in rats

Benzalkonium chloride (BAC), a disinfectant, and triethylene glycol (TEG), an organic solvent/sanitizer, are frequently combined in commercially available household sprays. To assess the respiratory effect of this combination, Sprague-Dawley rats were exposed to an aerosol containing BAC (0.5%, w/v) and TEG (10%, w/v) for up to 2 weeks in a whole-body inhalation chamber. BAC (4.1-4.5 mg/m³, sprayed from 0.5% solution) promoted pulmonary cell damage and inflammation as depicted by the increase in total protein, lactate dehydrogenase, polymorphonuclear leukocytes, and macrophage inflammatory protein-2 in the bronchoalveolar lavage fluid, whereas TEG (85.3-94.5 mg/m³, sprayed from 10% solution) did not affect the lung. Rats exposed to the BAC/TEG mixture for 2 weeks showed severe respiratory symptoms (sneezing, wheezing, breath shortness, and chest tightness), but no lung damage or inflammation was observed. However, significant ulceration and degenerative necrosis were observed in the nasal cavities of rats repeatedly exposed to the BAC/TEG mixture. The mass median aerodynamic diameters of the aqueous, BAC, TEG and BAC/TEG aerosols were 1.24, 1.27, 3.11 and 3.24 μm, respectively, indicating that TEG-containing aerosols have larger particles than those of the aqueous and BAC alone aerosols. These results suggest that the toxic effects of BAC and BAC/TEG aerosols on the different respiratory organs may be associated with the difference in particle diameter, since particle size is important in determining the deposition site of inhaled materials.

Influence of Intranasal Drugs on Human Nasal Mucociliary Clearance and Ciliary Beat Frequency

The nasal mucociliary clearance system, which comprises epithelial cilia and mucus from goblet cells, is an important intrinsic defense mechanism of the upper respiratory tract. Intranasal drugs and additives can have a detrimental effect on ciliary activity and mucociliary clearance, and thus impact the integrity of nasal defense mechanisms. This article discusses the current literature on the effects of different classes of intranasal drugs including intranasal corticosteroids, antihistamines, decongestants, antimicrobials and antivirals, as well as various drug excipients and nasal irrigation solutions on human nasal mucociliary clearance and ciliary beat frequency. Available data indicate that some intranasal formulations tend to hamper nasal ciliary function and mucociliary clearance. Therefore, it is of great importance to assess the effects of intranasal drugs and additives on mucociliary function before they are recommended as therapy for different nasal conditions.

[Medically-induced rhinitis]

This paper summarizes the currently accepted concepts of the pathogenetic mechanisms underlying the morphological and functional changes in intranasal mucosa of the patients having a long history of the application of the long-acting topical vasoconstrictor agents. The author presents the data illustrating the effectiveness of various methods for the pharmacotherapeutic treatment of medically-induced rhinitis.

Pulmonary Toxicity of Benzalkonium Chloride

The available toxicity data of benzalkonium chloride (BKC) clearly shows that it is toxic; however, the weight of evidence favors the view that at doses encountered in nasally and orally inhaled pharmaceutical preparations it is well tolerated. The adverse toxicological data predominantly come from in vitro and animal studies in which doses and exposure periods employed were excessive in relation to the clinical doses and their posology and, therefore, not directly applicable to the clinic. The conflict between the in vitro and animal data and the clinical experience can be reconciled by understanding some of the physicochemical properties of BKC, the nasal and respiratory tract microenvironments, the doses used, and the posology.

In vitro effects of preservatives in nasal sprays on human nasal epithelial cells

BACKGROUND

The preservatives benzalkonium chloride and potassium sorbate are widely used in nasal drops and sprays. Recently, side effects resulting from mucosal damage caused by benzalkonium chloride and potassium sorbate were reported.

METHODS

We investigated the toxicity of benzalkonium chloride and potassium sorbate on human nasal epithelial cells in vitro. Using primary human nasal epithelial cells, different concentrations of benzalkonium chloride, potassium sorbate, or phosphate-buffered saline (PBS; control group) solutions were cocultured with nasal epithelial cells for 15 minutes. Then, the viability of the cells and the cell morphology were assessed.

RESULTS

Nasal epithelial cells were more severely damaged with use of clinical preparations or higher concentrations of benzalkonium chloride than in the control group. In addition, nasal epithelial cell membrane lysis was seen on electronic microscopy in the benzalkonium chloride groups. In contrast, there was no significant cell damage seen in the potassium sorbate groups compared with the control group, even with higher concentrations than clinically used.

CONCLUSION

Potassium sorbate appears to be a relatively safer preservative than benzalkonium chloride for use in nasal sprays and drops in vitro study.

Mucociliary clearance – a critical upper airway host defense mechanism and methods of assessment

PURPOSE OF REVIEW

Mucociliary clearance is a critical host defense mechanism of the airways. Effective mucociliary clearance requires appropriate mucus production and coordinated ciliary activity. The important role of these two components is best demonstrated in disorders such as primary ciliary dyskinesia and cystic fibrosis, both of which lead to lifelong recurrent respiratory tract infections. We review the methods used to analyze mucociliary clearance.

RECENT FINDINGS

Utilization of microdialysis probes has improved temporal resolution of mucociliary clearance in murine airways, availing many genetic mouse models to critical mucociliary clearance analysis, while improved fixation technique for transmission electron microscopy has allowed for detailed resolution of the airway surface liquid. High-speed digital video analysis has improved quantification of ciliary beat frequency while advancements in air-liquid interface culturing techniques have generated in-vitro models to investigate mucociliary clearance.

SUMMARY

Advancements in techniques for analysis of mucociliary clearance have improved our understanding of the interaction between the respiratory epithelium and the airway surface liquid, resulting in the ability to study pathologic processes involving mucociliary clearance in great detail.