Osmolality and pH of anti-asthmatic drug solutions

Distribution and suitability of pulmonary surfactants as a vehicle for topically applied antibodies in healthy and SARS-CoV-2 infected rodent lungs

The use of natural pulmonary surfactants (PS) as a drug delivery vehicle for biologics is a more recent therapeutic modality. Herein, we tested different contents of PS regarding their physicochemical properties under stress conditions. The PS content of 12.25 mg/ml (Formulation B) showed desired properties such as an isotonic osmolality ∼300 mOsm/kg and an acceptable viscosity of 8.61 cSt, being lower than in commercially available PS solutions. Formulation B passed the specifications of surface lowering capacities of >80 % total lung capacity and physiologically desired formulation properties were independent of the antibody used in the composition. The identified formulation showed the capability of significantly increasing the oxygen saturation in ex vivo isolated perfused rat lungs, compared to a control and up to 30 min post lavage. In the in vivo setting, we showed that intratracheal administration of a human mAB with and without pulmonary surfactant led to higher amounts of delivered antibody within the alveolar tissue compared to intravenous administration. The antibody with the PS formulation remained longer in the alveolar tissues than the antibody without the PS formulation. Further, SARS-CoV-2 infected Golden Syrian hamsters showed that the intranasally applied antibody reached the site of infection in the alveoli and could be detected in the alveolar region 24 h after the last administration. With this work, we demonstrated that pulmonary surfactants can be used as a pulmonary drug delivery mechanism for antibodies and may subsequently improve the antibody efficacy by increasing the residence time at the desired site of action in the alveolar tissue.

In Vitro Effect of Combined Hypertonic Saline and Salbutamol on Ciliary Beating Frequency and Mucociliary Transport in Human Nasal Epithelial Cells of Healthy Volunteers and Patients with Cystic Fibrosis

Background: Inhalation of hypertonic saline (HS) is standard of care in patients with cystic fibrosis (CF). However, it is unclear if adding salbutamol has-besides bronchodilation-further benefits, for example, on the mucociliary clearance. We assessed this in vitro by measuring the ciliary beating frequency (CBF) and the mucociliary transport rate (MCT) in nasal epithelial cells (NECs) of healthy volunteers and patients with CF. Aims: To investigate the effect of HS, salbutamol, and its combination on (muco)ciliary activity of NECs in vitro, and to assess potential differences between healthy controls and patients with CF. Methods: NECs obtained from 10 healthy volunteers and 5 patients with CF were differentiated at the air-liquid interface and aerosolized with 0.9% isotonic saline ([IS] control), 6% HS, 0.06% salbutamol, or combined HS and salbutamol. CBF and MCT were monitored over 48-72 hours. Results: In NECs of healthy controls, the absolute CBF increase was comparable for all substances, but CBF dynamics were different: HS increased CBF slowly and its effect lasted for an extended period, salbutamol and IS increased CBF rapidly and the effect subsided similarly fast, and HS and salbutamol resulted in a rapid and long-lasting CBF increase. Results for CF cells were comparable, but less pronounced. Similar to CBF, MCT increased after the application of all the tested substances. Conclusion: CBF and MCT of NECs of healthy participants and CBF of patients with CF increased upon treatment with aerosolized IS, HS, salbutamol, or HS and salbutamol, showing a relevant effect for all tested substances. The difference in the CBF dynamics can be explained by the fact that the properties of the mucus are changed differently by different saline concentrations.

Nebulised Isotonic Hydroxychloroquine Aerosols for Potential Treatment of COVID-19

The coronavirus disease 2019 (COVID-19) is an unprecedented pandemic that has severely impacted global public health and the economy. Hydroxychloroquine administered orally to COVID-19 patients was ineffective, but its antiviral and anti-inflammatory actions were observed in vitro. The lack of efficacy in vivo could be due to the inefficiency of the oral route in attaining high drug concentration in the lungs. Delivering hydroxychloroquine by inhalation may be a promising alternative for direct targeting with minimal systemic exposure. This paper reports on the characterisation of isotonic, pH-neutral hydroxychloroquine sulphate (HCQS) solutions for nebulisation for COVID-19. They can be prepared, sterilised, and nebulised for testing as an investigational new drug for treating this infection. The 20, 50, and 100 mg/mL HCQS solutions were stable for at least 15 days without refrigeration when stored in darkness. They were atomised from Aerogen Solo Ultra vibrating mesh nebulisers (1 mL of each of the three concentrations and, in addition, 1.5 mL of 100 mg/mL) to form droplets having a median volumetric diameter of 4.3-5.2 µm, with about 50-60% of the aerosol by volume < 5 µm. The aerosol droplet size decreased (from 4.95 to 4.34 µm) with increasing drug concentration (from 20 to 100 mg/mL). As the drug concentration and liquid volume increased, the nebulisation duration increased from 3 to 11 min. The emitted doses ranged from 9.1 to 75.9 mg, depending on the concentration and volume nebulised. The HCQS solutions appear suitable for preclinical and clinical studies for potential COVID-19 treatment.

Contemporary Formulation Development for Inhaled Pharmaceuticals

Pulmonary delivery has gained increased interests over the past few decades. For respiratory conditions, targeted drug delivery directly to the site of action can achieve a high local concentration for efficacy with reduced systemic exposure and adverse effects. For systemic conditions, the unique physiology of the lung evolutionarily designed for rapid gaseous exchange presents an entry route for systemic drug delivery. Although the development of inhaled formulations has come a long way over the last few decades, many aspects of it remain to be elucidated. In particular, a reliable and well-understood method for in vitro-in vivo correlations remains to be established. With the rapid and ongoing advancement of technology, there is much potential to better utilise computational methods including different types of modelling and simulation approaches to support inhaled formulation development. This review intends to provide an introduction on some fundamental concepts in pulmonary drug delivery and inhaled formulation development followed by discussions on some challenges and opportunities in the translation of inhaled pharmaceuticals from preclinical studies to clinical development. The review concludes with some recent advancements in modelling and simulation approaches that could play an increasingly important role in modern formulation development of inhaled pharmaceuticals.

Compatible Stability and Aerosol Characteristics of Atrovent® (Ipratropium Bromide) Mixed with Salbutamol Sulfate, Terbutaline Sulfate, Budesonide, and Acetylcysteine

(1) Background: It is common practice in the treatment of respiratory diseases to mix different inhalation solutions for simultaneous inhalation. At present, a small number of studies have been published that evaluate the physicochemical compatibility and aerosol characteristics of different inhalation medications. However, none of them studied Atrovent^®. Our work aims to address the lack of studies on Atrovent^®. (2) Methods: Portions of admixtures were withdrawn at certain time intervals after mixing and were tested by pH determination, osmolarity measurement, and high-performance liquid chromatography (HPLC) assay of each active ingredient as measures of physicochemical compatibility. The geometrical and aerosol particle size distribution, active drug delivery rate, and total active drug delivered were measured to characterize aerosol behaviors. (3) Results: During the testing time, no significant variation was found in the pH value, the osmotic pressure, or the active components of admixtures. With the increase in nebulization volume after mixing, fine particle dose (FPD) and total active drug delivered showed statistically significant improvements, while the active drug delivery rate decreased compared to the single-drug preparations. (4) Conclusions: These results endorse the physicochemical compatibility of Atrovent^® over 1 h when mixed with other inhalation medications. Considering aerosol characteristics, simultaneous inhalation is more efficient.

Post-inhalation cough with therapeutic aerosols: Formulation considerations

This review provides an assessment of post-inhalation cough with therapeutic aerosols. Factors that increase cough may be mitigated through design of the drug, formulation, and device. The incidence of cough is typically less than 5% for drugs with a nominal dose less than 1 mg, including asthma and COPD therapeutics. Cough increases markedly as the dose approaches 100 mg. This is due to changes in the composition of epithelial lining fluid (e.g., increases in osmolality, proton concentration). Whether an individual exhibits cough depends on their degree of sensitization to mechanical and chemical stimuli. Hypersensitivity is increased when the drug, formulation or disease result in increases in lung inflammation. Cough related to changes in epithelial lining fluid composition can be limited by using insoluble neutral forms of drugs and excipients.

Aerosolised Antibacterials for the Prevention and Treatment of Hospital-Acquired Pneumonia

Aerosolised administration of antibacterials remains theoretically attractive for the prevention and treatment of hospital-acquired pneumonia (HAP) because of the ability to generate high drug concentrations at the site of infection. There is renewed interest in this area because of the shortcomings of current therapies and increasing multidrug resistance in Gram-negative organisms. Clinical trials of aerosolised or endotracheally administered antibacterials for HAP prevention have generally been positive; however, early trials were hampered by the development of resistance related to indiscriminate use. More recent trials have shown efficacy at HAP prevention without adverse effects on microflora as a result of more limited usage. However, prophylactic aerosolised antibacterials still need to be studied in large randomised trials before they could enter widespread use. The treatment of HAP with aerosolised antibacterials has mostly been reported in case series without control groups. Both early reports with aminoglycosides and the more recent use of colistin have reported very good response rates; even with organisms such as Pseudomonas aeruginosa and Acinetobacter baumannii. Aerosolised antibacterials were almost always added to intravenous therapy. On the basis of these reports, the current HAP guidelines allow the addition of aerosolised antibacterials in selected patients with multidrug-resistant organisms. This seems to be a reasonable recommendation until large trials are performed. Overall, toxicity was relatively low in the publications reviewed. Aerosolised drug administration in mechanically ventilated patients requires attention to a number of factors in order to maximise drug deposition in the lung.

Mechanism of efficient transfection of the nasal airway epithelium by hypotonic shock

The main barrier to gene transfer in the airway epithelium is the low rate of apical endocytosis limiting naked DNA uptake. Deionized water is known to stimulate the exocytosis of numerous intracellular vesicles during hypotonic cell swelling, in order to expand plasma membrane and prevent cell lysis. This is followed by the phase of regulatory volume decrease (RVD), during which the excess plasma membrane is retrieved by intensive endocytosis. Here we show that the more hypotonic the DNA solution, the higher the transfection of the nasal tissue. P2 receptors are known to be involved in RVD and we demonstrate that some P2 agonists and a P2 antagonist impair transfection in a time-dependent manner. Our study strongly suggests that the nasal airway epithelial cells take up plasmid DNA in deionized water during RVD, within approximately half an hour. Our simple gene delivery system may constitute a promising method for respiratory tract gene therapy.

Compatibility and osmolality of inhaledN-acetylcysteine nebulizing solution with fenoterol and ipratropium

PURPOSE

The compatibility, pH, and osmolality of N-acetylcysteine (NAC) nebulizing solution in the presence of ipratropium bromide or fenoterol hydrobromide were studied.

METHODS

Portions (400 microL) of each mixture were sampled immediately upon mixing and one, two, three, four, five, six, and seven hours after mixing and assayed by high-performance liquid chromatography. Osmolality was measured by sampling 100 microL from the filling cup at a five-minute interval during nebulization and by the freezing-point-depression method.

RESULTS

Adding NAC solution to fenoterol solution raised the pH from 3.20 to 7.90 and the osmolality to a mean +/- S.D. of 1400.67 +/- 4.51 mOsm/kg. Fenoterol concentrations decreased to 93.71% and NAC concentrations to 92.54% of initial concentrations after seven hours. Mixing ipratropium with NAC solution raised the pH from 3.74 to 7.95 and the osmolality to a mean +/- S.D. of 1413 +/- 11.79 mOsm/kg. The initial ipratropium concentration declined 7.39% and 10.91% one and two hours after mixing with NAC solution, respectively.

CONCLUSION

NAC and ipratropium were stable in nebulizing solution within one hour of mixing. NAC and fenoterol were compatible for at least seven hours.

Role of airway endogenous nitric oxide on lung function during and after exercise in mild asthma

We hypothesized that nitric oxide (NO), a known mild bronchodilator that can be released by several cell types within pulmonary airways, might protect airways during exercise in asthmatic subjects. We studied 17 individuals with documented exercise-induced asthma (screening exercise evaluation) on 2 study days: after treatment with inhaled NO synthase inhibitor N(G)-monomethyl-l-arginine (l-NMMA; 2 ml of 25 mg/ml mist) and after treatment with saline vehicle. Pulmonary resistance (Rl, esophageal manometry) rose and forced expiratory volume in 1 s fell more after l-NMMA compared with saline treatment, suggesting a bronchoprotective role for NO at baseline. The rise in Rl seen after l-NMMA treatment was nearly completely reversed early in exercise, suggesting a non-NO-mediated bronchodilation. A slow rise in Rl during constant-load exercise and dramatic increase in Rl after exercise were the same on the 2 treatment days, indicating little role for NO in regulating airway function during and after exercise. We conclude that endogenous NO plays little role in regulating airway function during and after exercise in subjects with mild asthma.

Nebulizer choice for inhaled colistin treatment in cystic fibrosis

STUDY OBJECTIVES

To develop practical ways of nebulizing colistin by determining the rate of drug output, total drug output, and particle-size distribution of two commercially available jet nebulizers, the disposable Hudson 1730 Updraft II (Hudson Respiratory Care; Temecula, CA) and the reusable Pari LC Star breath-enhanced nebulizer (Pari Respiratory Equipment; Midlothian, VA).

METHODS

The nebulizers contained colistin, 75 mg, in 4 mL of isotonic solution. Particle-size distribution was measured by helium-neon laser diffraction, allowing calculation of the respirable fraction (RF), the mass of aerosol comprised of droplets < 5 microm.

RESULTS

The mean (95% confidence interval [CI]) total rate of output of the Updraft II was 2.6 mg/min (2.0, 3.1; n = 4) with 1.3 mg/min (1.0, 1.5) mg/min within the RF. The rate of output of the LC Star increased in a quadratic relationship to the inspiratory flow, delivering 1.8 mg/min (0.7, 2.0; n = 4) with 1.4 mg/min (1.3, 1.6) within the RF, and 6.2 mg/min (5.6, 6.8) with 5.3 mg/min (4.8, 5.7) within the RF, at 0 L/min and 20 L/min inspiratory flows, respectively. Efficiency, as the rate of expected pulmonary deposition divided by rate of total output, was then calculated. The LC Star estimated 56% (51, 61) efficiency, with pulmonary delivery of 29% (26, 32) of the charge of the nebulizer, compared to the Updraft II at 22% (22, 23) efficiency and expected pulmonary deposition of 10% (10, 10) of the dose.

CONCLUSIONS

Colistin can be successfully nebulized with both nebulizers tested. This study provides an estimate of in vivo efficiency and expected pulmonary deposition that may be used in future trials.

Aerosolized antimicrobial therapy in acutely ill patients

Recent data are sparking renewed interest in therapy with aerosolized antimicrobials in critically ill patients as well as other populations such as those with neutropenia, human immunodeficiency virus infection, and cystic fibrosis. Pneumonia is a common complication in these patients and is associated with substantial morbidity and increased mortality. Clinical trials evaluated aerosolized antimicrobials for the prevention and treatment of pneumonia in hospitalized patients. In addition, factors that affect the pulmonary deposition of aerosolized drugs in mechanically ventilated patients were identified.

Effect of nebulizer type and antibiotic concentration on device performance

We compared the performance of selected ultrasonic and jet nebulizers when aerosolizing several antibiotic formulations to determine optimum combinations for delivery of a respirable antibiotic aerosol. Three ultrasonic devices were tested: the UltraNeb 99/100, the UltraAIR and the Aerosonic. The reusable jet nebulizers were the Dura ProNeb, Pari-LL and the Sidestream. The six disposable jet nebulizers were Marquest Acorn II, Hudson T Updraft II, Baxter MistyNeb, Pari-LC, Pari IS-2, and a disposable Sidestream. Each jet was tested with four compressors: a DeVilbiss AP-50, a Pulmo-Aide, a DuraNeb and a PariMaster. All nebulizing systems were initially tested with normal saline. From the initial data, six jet nebulizers and one ultrasonic device were tested with varying concentrations of tobramycin, gentamicin, ceftazidime, ciprofloxacin and colistin. Output was assessed by measuring volume (milliliters per minute), and amount of drug (milligrams per minute) nebulized. We then measured mean particle size of the antibiotic aerosol with seven jet nebulizers and two different compressors, Pulmo-Aide and PariMaster, and two ultrasonic devices. The rate of nebulization of saline and antibiotic solutions (milliliters per minute) was greater with the ultrasonic device(s) than all jet nebulizer systems tested. Increasing the reservoir antibiotic concentration increased the drug output (milligrams per minute) with the jet nebulizers to a maximum, followed by decreasing output. When antibiotic concentrations were increased the output decreased more precipitously with the ultrasonic devices than with the jet nebulizers. At the highest antibiotic concentrations tested, the ultrasonic devices had the lowest output. Particle size distribution was most dependent on the specific jet device, with particle size distribution less affected by a specific antibiotic or its concentration. Higher reservoir concentrations can be utilized for increasing output of respirable antibiotic aerosols by jet nebulizers. We conclude that antibiotic output is dependent upon both the nebulizing system and the reservoir concentration of antibiotic.

Terbutaline nebulization and epinephrine injection in treating acute asthmatic children

Ninety children with acute asthma, equally divided into two study groups, were studied to compare the efficacy and safety of nebulized terbutaline with injected epinephrine in the treatment of acute exacerbation. The terbutaline group received 2 ml (5,0 mg) terbutaline solution diluted with 2 ml 0.9% saline for inhalation over 10 minutes; the epinephrine group received 0.01 ml/kg of 1:1000 epinephrine (maximum 0,3 ml) through subcutaneous injection at deltoid area. Spirometry, pulse oximetry, and clinical severity scoring system were evaluated at baseline and again 15 minutes after treatment. The baseline data of the two groups were not significantly different. The clinical severity score and spirometry of both groups were significantly improved after treatment. Compared with the terbutaline group, the epinephrine group had better mean oxygen saturation (SaO2; p < 0.001), frequency of oxygen desaturation (p = 0.0028) and forced expiratory flow 25-75% (FEF25-75%, p = 0.027). For those patients with initial forced expiratory volume in one second (FEV1) lower than 60% of predicted value, epinephrine treatment was more effective in the improvement of FEV1, FEF25-75%, and oxygen saturation (SaO2) (p = 0.011, 0.012, and 0.006, respectively). A Significantly higher rate of adverse effects occurred in patients given epinephrine (47% vs 11%, p = 0.0002); these included pallor, tremor, dizziness, headache, palpitation, soreness of legs, numbness of extremities, cold sweating, general weakness and nausea. Considering the general trend to noninvasive therapy in children and the more frequent adverse effects after epinephrine injection, such nebulized beta-2 agonists as terbutaline appear preferable for initial therapy of acute asthma if oxygen is supplemented to prevent possible hypoxemia. However, parenteral epinephrine still is worth trying, particularly in any severe, life-threatening attack.

Metered dose inhaler and nebuliser in acute asthma

One hundred and eleven children with acute asthma were studied to compare delivery of terbutaline by either a metered dose inhaler (MDI) with a valved holding chamber or a nebuliser driven by air. Eligible patients were randomised; the MDI group received three puffs (0.75 mg) of terbutaline and the nebuliser group received 2 ml (5.0 mg) terbutaline solution diluted with 2 ml 0.9% saline for inhalation over 10 minutes. Patients were evaluated by spirometry, pulse oximetry, and clinical severity scoring system at baseline and again 15 minutes after the beginning of treatment. The baseline data of the two groups were not significantly different. All parameters of spirometry, except the peak expiratory flow (PEF) for the nebuliser group, and clinical severity score for both groups significantly improved after terbutaline treatment. Compared with the nebuliser group, the MDI group after treatment had better mean (SD) oxygen saturation (SaO2; 96.82 (1.63)% v 95.44 (1.88)%), frequency of oxygen desaturation (23.2% v 47.3%), absolute increase of PEF (32.6 (37.7) l/min v 10.2 (34.7) l/min), and SaO2 (0.54 (1.64)% v -0.47 (1.84)%). There was also a mean (SD) per cent increase of forced expiratory volume in one second (22.9 (21.0)% v 15.4 (16.1)%), PEF (27.7 (38.4)%) v 7.7 (25.1)%), and SaO2 (0.58 (1.72)% v -0.47 (1.93)%). In conclusion, aerosol treatment by MDI (with a valved holding chamber) in this study proved to be superior to nebuliser treatment in terms of SaO2 and some measurements of spirometry. Respiratory therapists working with children with severe asthma should be aware of the possibility of oxygen desaturation, especially when using room air as the driving gas for nebulisation.

Prediction and experimental determination of solute output from a Collison nebulizer

The total output from a nebulizer is made up of aqueous droplets containing solute and a significant component of water vapor. The solvent loss is reflected in an increase in the nebulizer solution concentration over time and this has been described mathematically. This theory, originally described by Mercer et al., was modified to describe the solute output from a three-jet Collison nebulizer. The influence of concentration, air flow (air pressure), volume, and temperature on the output parameters were then studied. Inlet air pressures were 10 (4.1), 20 (6.4), and 40 (10.0) psig (L/min), starting concentrations were 0.1, 2, and 5% (w/w) and initial solution volumes were 10 and 20 mL. To study temperature effects, solutions were nebulized at fixed temperatures ranging from 4 to 50 degrees C. This was achieved by water-jacketing the nebulizer flask. Test solutions consisted of mannitol and a fixed concentration of 11.1 micrograms/mL carboxyfluorescein. Nebulization was carried out for up to 30 min using dry, filtered air at ambient temperature. Total output was determined gravimetrically while solute output was determined by fluorimetry (495-nm excitation, 515-nm emission). Solution concentration changes were also monitored over time by fluorimetry. The results show that the solution and solvent output parameters are independent of concentration, volume, and air flow within the ranges studied but that solvent output, in particular, is highly dependent upon temperature.