Comparative pharmacokinetics of salbutamol inhaled from a pressurized metered dose inhaler either alone or connected to a newly enhanced spacer design

Assessing of low-tech solutions for aerosol delivery: Comparative performance study of manufactured versus homemade spacers

PURPOSE

This study aims to evaluate the performance of low-cost homemade spacers compared with manufactured valved holding chambers (VHCs) for fluticasone propionate delivery via a pMDI (pressurized Metered Dose Inhaler).

METHODS

The Total Emitted Dose (TED) and particle size distribution were measured for pMDI alone or connected to the different spacers, according to CAN/CSA-Z264.1-02 standard. Two types of low-cost alternative and manufactured spacers were investigated: 500 mL plastic bottle and 553 mL aluminium can; non-antistatic plastic VHCs and aluminium antistatic VHCs.

RESULTS

The TED of homemade plastic bottle vs plastic VHC were similar in the 20-23% range. In contrast, the TED of homemade aluminium can was higher compared to aluminium VHC (83% vs 68%). The Fine Particle Fraction (FPF) was similar for the two plastic-based spacers (in the 12.68-17.60% range), although it was greater for the aluminium can compared to aluminium VHC (51% vs 42%). However, all spacers have limited large particles fraction, mainly deposited in the oropharyngeal tract, potentially decreasing side effects.

CONCLUSION

We demonstrated that low-tech solutions as homemade spacers have at least similar performances to VHC medical devices composed of same material (aluminium or plastic). Thus, low-cost homemade spacers represent alternatives in case of emergency and without VHCs nearby.

Relative Lung and Systemic Bioavailability Along with Oropharyngeal Deposition of Salbutamol Post-Inhalation: A Pharmacokinetic Evaluation of Novel Inhaler Technique Training Gadgets

Background: Suboptimal use of pressurized metered dose inhaler (pMDI) remains a major barrier to inhaled therapy success. Verbal inhaler technique training (VT) fails to maintain patients' good pMDI use, thus training tools might help. Trainhaler^® (THR device) and Flo-Tone^® CR (FTCR device), two novel pMDI technique training tools, were evaluated and compared in terms of relative lung and systemic bioavailability and oropharyngeal deposition of salbutamol inhaled from Ventolin^® Evohaler^® (GlaxoSmithKline) either alone following THR or connected to FTCR. Methods: Sixteen healthy adults inhaled 2 × 100 μg salbutamol puffs (1 minute apart) from Ventolin using the THR device or FTCR device in a two-period, randomized crossover study. A 7-day washout separated THR and FTCR approaches. Immediately after each puff inhalation, each subject gargled with 20 mL water for oropharyngeal deposition determination. Urine samples were collected 0.5 hour (pre-inhalation) and 0.5, 1.0, and 2.0 hours post-inhalation. Urine was then pooled till 24-hour post-inhalation. The relative lung bioavailability (0- to 0.5-hour urinary salbutamol excretion-USAL0.5) and relative systemic bioavailability (0- to 24-hour urinary excretion of salbutamol and its metabolite-USALMET24) were determined. Results: The mean (standard deviation [SD]) USAL0.5 of the THR and FTCR groups was 5.70 (6.43) and 11.39 (9.67) μg, respectively. The mean (SD) oropharyngeal deposition was 11.11 (4.37) and 6.09 (1.89) μg, respectively. The THR and FTCR devices were statistically significantly different in USAL0.5 and oropharyngeal deposition (p < 0.001), whereas there was no statistically significant difference in USALMET24. Conclusion: The THR device and the FTCR device showed positive impact on inhaled pMDI delivery. Indeed, the FTCR device doubled the relative lung bioavailability and minimized the unwanted oropharyngeal deposition of inhaled salbutamol. In practice, these pMDI trainers would complement and maintain VT. Study Registration: The study was registered on the ISRCTN registry (Reference: ISRCTN88332465-06/12/2017 [Prospectively Registered]).

Lung deposition and systemic bioavailability of dose delivered to smoker compared with non-smoker COPD subjects

INTRODUCTION

Inhaled drugs are the most commonly used class of medications for COPD subjects. No studies have been performed to assess the influence of smoking on lung deposition of aerosolized medication, especially for the exacerbated COPD subject. The present study aimed to assess the influence of smoking on the lung deposition of the aerosol delivered to exacerbated COPD subjects.

METHODS

Twenty-four exacerbated COPD subjects using automatic continuous positive airway pressure (Auto-CPAP), 12 smokers (six females) and 12 non-smokers (six females) were recruited in the study. The subjects participated in the study received four salbutamol study doses; 1200 µg (12 puffs 100 µg/puff) of salbutamol emitted from pMDI canister connected to AeroChamber MV spacer; 1200 µg of salbutamol emitted from pMDI canister connected to Combihaler spacer; 1 mL of salbutamol respirable solution (5000 µg/mL) nebulized by Aerogen Solo connected to its T-piece; and 1 mL of salbutamol respirable solution nebulized by Aerogen Solo connected to Combihaler spacer with 2 puffs salbutamol MDI (200 µg salbutamol) before nebulisation. The subjects were randomised to receive the four selected dose-adaptor combination in a sealed envelope design on days 1, 3, 5 and 7. A washout period of 24 hours was provided between each salbutamol dosing. Auto-CPAP was adjusted at non-invasive ventilation mode with the integrated heated humidifier, as a source of humidity. Urine samples were provided by subjects, 30 minutes and cumulatively 24 hours post inhalation, as an index of the relative and systemic bioavailability, respectively, and aliquots were retained for salbutamol analysis using solid-phase extraction and high-performance liquid chromatography (HPLC). On day 2 of the study, a collecting filter was placed between the aerosol generator and the subject's mask so that the subjects would not inhale the salbutamol delivered. The same study doses and/or adapters were delivered to each subject, with filters changed with each dose-adapter combination. Salbutamol entrained on the filter was desorbed to be analysed by the HPLC.

RESULTS

Significantly higher lung deposition (30 minutes urinary salbutamol) was detected with the non-smoker compared with smokers (P < .05). Significantly higher systemic bioavailability (pooled 24-hour urinary salbutamol) for smokers compared with non-smokers was found with Aerogen Solo connected to its T-piece and CombiHaler spacer with pMDI (P < .05) only. Significantly higher amount desorbed from the ex-vivo filter were found from pMDI with both spacers in non-smokers (P < .05) compared with the smokers.

CONCLUSION

The study demonstrated that smoking reduced the lung deposition of inhaled salbutamol delivered by nebulizer or pMDI. However, the smoking effect on cytochrome p450 was observed to increase systemic absorption of the ingested portion of the inhaled dose. The lower lung deposition and possible higher systemic absorption should be taken into consideration while prescribing inhaled medication to COPD smokers especially exacerbated patients that need ventilation. Further studies are needed.

A 3D printed human upper respiratory tract model for particulate deposition profiling

Pulmonary route is the main route of drug delivery for patients with asthma and chronic obstructive pulmonary diseases, offering several advantages over the oral route. Determining the amount of drug deposited onto various parts of the respiratory tract allows for a good correlation to clinical efficacy of inhalation drug devices. However, current in vitro cascade impactors measure only the aerodynamic particle size distribution, which does not truly represent the in vivo deposition pattern in human respiratory tract. In this study, a human upper respiratory tract model was fabricated using a 3D printer and subsequently characterized for its dimensional accuracy, surface finishing and air leaking. The effects of using a spacer and/or various airflow rates were also investigated. To assess this in vitro model, the deposition pattern of a model drug, namely, salbutamol sulphate, was tested. The resultant deposition pattern of salbutamol sulphate from a metered dose inhaler at 15 L per minute with the spacer, showed no significant difference from that of a published radiological in vivo study performed in adult humans. In addition, it was also found that the deposition pattern of salbutamol at 35 L per minute was comparable to the results of another published study in human. This in vitro model, showing reasonable in vitro-in vivo correlation, may provide opportunities for personalized medicine in special populations or disease states.