Immediate effect of benzalkonium chloride in decongestant nasal spray on the human nasal mucosal temperature

Screening of Concentration and Antimicrobial Effectiveness of Antimicrobial Preservative in Betastatin Besylate Nasal Spray

Objective

To explore the optimal concentration and antimicrobial effectiveness of antimicrobial preservative in betastatin besylate nasal spray.

Methods

By using Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, and Aspergillus niger as test strains, the antimicrobial effectiveness of betastatin besylate nasal spray containing different concentrations of antimicrobial preservative (0.02%, 0.0125%, and 0.005% benzalkonium chloride, respectively) was determined by using bacteriostatic effect test (Chinese Pharmacopoeia, 2015 edition).

Results

The antimicrobial effectiveness of betastatin besylate nasal spray containing 0.02% and 0.0125% benzalkonium chloride, respectively, complied with the regulations of Chinese Pharmacopoeia (2015 Edition) against five test strains. However, the antimicrobial effectiveness of betastatin besylate nasal spray containing 0.005% benzalkonium chloride against P. aeruginosa did not meet the requirements of Chinese Pharmacopoeia.

Conclusion

Benzalkonium chloride at a concentration of 0.125% can be used as an added antimicrobial preservative in betastatin besylate nasal spray.

Numerical Simulation of Airflow Patterns and Air Temperature Distribution during Inspiration in a Nose Model with Septal Perforation

Background

The most typical symptoms of patients with nasal septal perforation (SP) are crusting and recurrent nosebleed. The objective of the study was to determine the influence of SP on intranasal temperature profile and airflow patterns during inspiration by means of numerical simulation.

Methods

Two realistic bilateral models of the human nose with and without SP were reconstructed based on computed tomography (CT). A numerical simulation was performed. The intranasal air temperature distribution and airflow patterns during inspiration were displayed, analyzed, and compared.

Results

SP causes a highly disturbed airflow in the area of perforation. A spacious vortex within the perforation including various localized vortices was detected. A disturbed intranasal temperature distribution between the right and left nasal cavities developed.

Conclusions

The numerical simulation demonstrates the interaction between airflow patterns and heating of respiratory air. The disturbed airflow causes reduced air conditioning. This fact may contribute to crusting and recurrent nosebleed.

Numerical simulation and nasal air-conditioning

Heating and humidification of the respiratory air are the main functions of the nasal airways in addition to cleansing and olfaction. Optimal nasal air conditioning is mandatory for an ideal pulmonary gas exchange in order to avoid desiccation and adhesion of the alveolar capillary bed. The complex three-dimensional anatomical structure of the nose makes it impossible to perform detailed in vivo studies on intranasal heating and humidification within the entire nasal airways applying various technical set-ups. The main problem of in vivo temperature and humidity measurements is a poor spatial and time resolution. Therefore, in vivo measurements are feasible only to a restricted extent, solely providing single temperature values as the complete nose is not entirely accessible. Therefore, data on the overall performance of the nose are only based on one single measurement within each nasal segment. In vivo measurements within the entire nose are not feasible. These serious technical issues concerning in vivo measurements led to a large number of numerical simulation projects in the last few years providing novel information about the complex functions of the nasal airways. In general, numerical simulations merely calculate predictions in a computational model, e.g. a realistic nose model, depending on the setting of the boundary conditions. Therefore, numerical simulations achieve only approximations of a possible real situation. The aim of this review is the synopsis of the technical expertise on the field of in vivo nasal air conditioning, the novel information of numerical simulations and the current state of knowledge on the influence of nasal and sinus surgery on nasal air conditioning.

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.

Nasal mucosal temperature in relation to nasal airflow as measured by rhinomanometry

BACKGROUND

The aim of this study was to measure in vivo nasal mucosal temperature and assess its relationship to nasal patency.

METHODS

Nasal mucosal temperature of 30 nasal cavities was measured by means of a miniaturized thermocouple within the anterior turbinate area during respiration. Temperature values were compared with corresponding rhinomanometrical data.

RESULTS

The median mucosal temperature ranged from 30.2 degrees C (range, 28.9-31.7 degrees C) after inspiration to 32.2 degrees C (range, 31.0-33.9 degrees C) after expiration. The end-inspiratory (r = -0.85) and end-expiratory mucosal temperature values (r = -0.88) negatively correlated with the rhinomanometrical data.

CONCLUSION

This study supports the fact that there is a negative correlation between nasal mucosal temperature and nasal resistance. Changes in nasal patency seem to influence nasal mucosal temperature. Within this context, nasal thermoreceptors might play an important role concerning the perception of nasal patency.

Simultaneous in vivo measurements of intranasal air and mucosal temperature

Nasal cavity volume and blood temperature along the nasal airways, reflecting the mucosal temperature, are considered to be the most important predictors of nasal air conditioning. The purpose of this study was to simultaneously in vivo measure intranasal air as well as mucosal temperature for the first time. Fifteen healthy subjects were enrolled into the study. Two combined miniaturized thermocouples were used for simultaneous recording of intranasal air and mucosal temperature within the anterior turbinate area close to the head of the middle turbinate without interruption of nasal breathing. The highest air and mucosal temperature values were detected at the end of expiration, the lowest values at the end of inspiration. The difference was statistically significant (P < 0.05). The mean mucosal temperature ranged from 30.2 +/- 0.9 to 32.2 +/- 0.8 degrees C. The mean air temperature ranged from 28.5 +/- 1.2 to 34.1 +/- 0.7 degrees C. The mean differences between air and mucosal temperature were 1.7 +/- 0.5 degrees C after inspiration and 1.9 +/- 0.7 degrees C after expiration. Simultaneous measurements of intranasal air and mucosal temperature are practicable. The detected temperature gradient between air and mucosa confirm a relevant heat exchange during inspiration and expiration. This gradient between air and mucosa is obligatory for heat and water exchange to ensure adequate nasal air conditioning.