Valved Holding Chambers and In Vitro Metered Dose Inhaler Performance: Effects of Flow Rate and Inhalation Delay

Comparative performance study of paperboard disposable spacers versus commercial valved holding chambers for aerosol delivery

PURPOSE

The aim of this study is to evaluate and compare the performance, for the administration of fluticasone propionate with a pressurized metered-dose inhaler (pMDI), of two low-tech paperboard spacers versus two commercially available valved holding chambers (VHC).

METHODS

According to the Canadian standard CAN/CSA-Z264.1-02, total emitted dose (TED) and aerodynamic size distribution were measured for the pMDI in combination with 4 different spacers: a homemade paper cup spacer, the DispozABLE® paperboard spacer, the AeroChamber Plus® plastic VHC, and the Vortex® aluminium VHC.

RESULTS

The two disposable paperboard spacers had a lower TED compared to the aluminium VHC, but delivered more than 2.5 times the dose of fluticasone than the commercial plastic VHC. The 3 antistatic devices (i.e. the aluminium VHC, the paperboard DispozABLE® spacer and the paper cup spacer) delivered a significantly higher dose of fine particles than the less antistatic plastic VHC. Their fine particle fraction was statistically similar to that obtained with pMDI without spacer. This respirable fraction ensures an optimal therapeutic effect. All spacers limited the flow of coarse particles, thus avoiding adverse effects on the trachea and oropharynx.

CONCLUSION

We have shown that inexpensive and low-tech paperboard spacers are interesting alternatives for the administration of aerosols.

Optimal Inhalation Profile of Pressurized Metered Dry Powder Inhaler Using a Valved Holding Chamber: A Dynamic Analysis

Background: The combined use of a pressurized metered-dose inhaler and valved holding chamber (pMDI+VHC) is recommended to improve efficiency and safety; however, aerosol release is likely to vary with the inhalation maneuver. This in vitro study investigated the aerodynamic characteristics and aerosol release features of pMDI+VHC (Aerochamber, Trudell Medical International). Methods: The static and dynamic changes in the airway resistance (Raw) during inhalation (withdrawal) through pMDI+VHC were measured. Subsequently, the aerosol released from pMDI+VHC was measured using simplified laser photometry during withdrawal with either fast ramp-up then steady or slow ramp-up followed by gradual decrement at different intensities and times to peak flow (TPWF). Results: Raw increased linearly with changes in the withdrawal flow (WF) rate between 10 and 50 L/min. The slope was steep in the low WF range (<50 L/min) and became milder in the higher range. The aerosol mass tended to increase with an increase in the peak WF (PWF) of slow ramp-up profile. When three different WF increment slopes (TPWF: 0.4, 1.4, and 2.4 seconds) were compared, the released aerosol mass tended to decrease, and the aerosol release time was prolonged at longer TPWF. When the PWF was increased, the aerosol release time became shorter, and the withdrawn volume required for 95% aerosol release became larger; however, it did not exceed 0.4 L at suitable TPWF (0.4 seconds). Conclusion: Raw analysis suggests that inhalation at 30-50 L/min is suitable for pMDI+VHC in this setting. Rapid (TPWF, 0.4 seconds) inhalation, but not necessarily long (maximum 2.0 seconds) and deep (but larger than 0.55 L), is also recommended. Practically, direct inhalation to be weaker than usual breathing, as fast as possible, and far less than 2.0 seconds.

Consequences of not-shaking and shake-fire delays on the emitted dose of some commercial solution and suspension pressurized metered dose inhalers

BACKGROUND

Pressurized metered-dose inhalers (pMDIs) include hydrofluoroalkane (HFA) propellant to generate a drug aerosol upon actuation and drugs can be formulated as solution or suspension. Suspended particles can cream or sediment depending on density differences between drug and propellant and shaking the pMDI is an essential step to ensure a uniform drug dose release.

RESEARCH DESIGN AND METHODS

The effect of the delay (0, 10, 30, 60 seconds) in pMDI actuation after shaking and the effect of no-shaking during the canister life on the emitted dose (ED) for commercial solution and suspension pMDIs was investigated.

RESULTS

The ED for solutions was unaffected by no-shaking or by the progressive increasing delay in actuation after shaking (between 77% and 97%). For all the suspension products, shaking was demonstrated to be critical to assure the close to nominal drug delivery. In detail, the actuation delay after shaking led to an increase up to 380% or a drop to 32% of ED in relation to the label claim with high variability.

CONCLUSION

The drug delivered can vary widely for no-shaking and over different shake-fire delays with suspension pMDIs while solution formulations appear to remain stable.

Particle Size Distribution Analysis of OTC Aerosol or Powder Drug Products With Potential for Inadvertent Inhalation Exposure to Consumers

The potential for inadvertent inhalation of over-the-counter (OTC) aerosol/powder drug products for topical application requires understanding of the characteristic size distributions of the airborne particles or droplets generated when these products are used as per the directions on the product label. Particle/droplet size is an important factor in determining the depth of particle penetration into the respiratory system after inhalation. Because particles penetrating beyond the larynx into the lung may lead to adverse respiratory effects, OTC aerosol or powder drug product particle size distribution is important to characterize. In this study, laser diffraction was used to analyze the particle size distribution of 32 currently marketed OTC drug products as emitted after actuation or air dispersion from their final package. Among the products surveyed were sunscreens, antiperspirants, topical analgesics, skin protectants, and acne products. The results may be useful to the U.S. Food and Drug Administration in its mission to protect as well as promote public health.

Usefulness of Nonvalved Spacers for Administration of Inhaled Steroids in Young Children with Recurrent Wheezing and Risk Factors for Asthma

Background

In vitro and scintigraphic studies have suggested that effectiveness of metered-dose inhalers (MDI) with nonvalved spacers (NVS) is similar to that of MDI with valved holding chambers (VHC). Nevertheless, there are no clinical studies that compare these techniques in long-term treatment with inhaled steroids in young children with recurrent wheezing and risk factors for asthma.

Objective

To compare the efficacy of a long-term treatment with Fluticasone Propionate administered by an MDI through both type of spacers, with and without valves, in young children with recurrent wheezing and risk factors for asthma.

Patients and Methods

Outpatient children (6 to 20 months old) with recurrent wheezing and risk factors for asthma were randomized to receive a 6-month treatment with metered-dose inhaler (MDI) of Fluticasone Propionate 125 mcg BID through an NVS or through a VHC. Parents recorded daily their child's respiratory symptoms and rescue medication use.

Results

46 patients of 13.4 ± 5 months old were studied. During the study period, the NVS group (n=25) experienced 3.9 ± 2.4 obstructive exacerbations, and the VHC group (n=21) had 2.6 ± 1.6 (p=0.031). The NVS group had 17.4 ± 14% of days with respiratory symptoms, and the VHC group had 9.7 ± 7% (p=0.019). The NVS group spent 29.8 ± 22 days on albuterol while the VHC group spent 17.9 ± 11 days (p=0.022).

Conclusion

Long-term treatment with inhaled steroids administered by MDI and NVS is less effective than such treatment by MDI and VHC in infants with recurrent wheezing and risk factors for asthma.

Use of spacers for patients treated with pressurized metered dose inhalers: focus on the VENTOLIN™ Mini Spacer

INTRODUCTION

Spacers offer a multitude of benefits by reducing the requirement to coordinate inhalation with actuation and improving inhaler technique in patients using a pressurized metered dose inhaler (pMDI). Spacers improve drug targeting by retaining within the spacer large particles normally deposited in the oropharynx, and by creating a prolonged aerosol cloud of fine particles to give the user increased time to inhale after actuation. This is particularly important in young children and the elderly to effectively deliver medication to the airways.

AREAS COVERED

By investigating the history and features of spacers, we demonstrate that the advantages of using spacers far outweigh their limitations. We also discuss the optimal characteristics of spacers in terms of shape, volume, presence of valve and static charge, and present a detailed discussion of the VENTOLIN™ Mini Spacer.

EXPERT OPINION

Generally, the shape and size of spacers makes them inherently inconvenient. Consideration of human factors and modern design may make them more attractive to patients. However, the incentive to use spacers should be their ability to help patients correctly use inhaled medications delivered by pMDIs. Understanding of these principles through education is key to their acceptance by patients.