Validation of methodology for recording breathing and simulating drug delivery through spacers and valved holding chambers

Optimal administration of bronchodilators with valved holding chambers in preschool children: a review of literature

Our aim was to synthesize the published literature on factors that potentially affect the delivery of bronchodilators using valved holding chambers (VHC) in preschool children. We also aimed to identify those attributes that are not yet incorporated or clearly stated in the guidelines and those topics that are still lacking sufficient data. There is strong evidence supporting several recommendations in current guidelines. Based on present knowledge, bronchodilators should be delivered by VHC administering each puff separately. Face mask should be omitted as soon as the child can hold the mouthpiece of the VHC tightly between the lips and teeth. Based on the review, we suggest adding a specific note to current guidelines about the effect of chamber volume and the impact of co-operation during drug administration. Calming the child and securing a tight face-to-mask seal is critical for successful drug delivery. There is not enough evidence to make specific recommendations on the most reliable VHC and face mask for children. There is an urgent need for studies that evaluate and compare the effectiveness of VHCs in various clinical settings in wide age-groups and respiratory patterns. In addition, there is insufficient data on ideal chamber volume, material, and effective antistatic treatment. What is Known: • Valved holding chambers (VHC) should not be considered interchangeable when used with pressurized metered dose inhalers (pMDI). • Drug delivery is influenced by VHC volume, aerodynamic and electrostatic properties; mask fit; respiratory pattern and co-operation during inhalation; and the number of puffs actuated. What is New: • The impact of co-operation, VHC volume, and good mask-to-face fit during drug inhalation is not stressed enough in the guidelines. • Studies are urgently needed to evaluate the effectiveness of different VHCs in various clinical settings focusing on VHC electrostatic properties, respiratory patters, face masks, and ideal pMDI+VHC combinations.

In vitro drug delivery performance of five valved holding chambers with and without facemasks

BACKGROUND

Valved holding chambers (VHCs) are essential for efficient pulmonary delivery of inhaled medication in preschool children. The numerous devices in the market vary in material, aerodynamic characteristics, volume, valve properties, and mask design. Drug delivery is affected by the VHC characteristics as well as by the age and breathing pattern of the child.

METHODS

We measured the drug delivery efficacy of five VHCs widely available in the market, evaluated the effect of facemasks and tested the differences between manufacturing lots. A breathing simulator was used to mimic normal (respiratory rate [RR] 25/minute and tidal volume (V_T ) 200 mL) and obstructive (RR 50/minute and V_T 50 mL) breathing of infants and toddlers.

RESULTS

Salbutamol output was significantly higher with a normal breathing pattern compared to the obstructive breathing pattern in most VHCs. Without masks, the differences in the median in vitro filter doses of salbutamol were mainly from 2 to 10-fold among different types of VHCs. With masks, there was a greater than 20-fold difference in drug delivery capacity between the most and least effective devices. Most VHCs had a notable variation of performance between individual devices from different lots within the same brand.

CONCLUSIONS

There was an extreme variation in the salbutamol delivery performance among different types of VHCs for both normal and obstructive pediatric breathing patterns with and without masks. This magnitude of performance variability can have significant and unpredictable clinical implications.

Valved holding chamber drug delivery is dependent on breathing pattern and device design

Small children with airway obstruction breathe with very low tidal volumes (V_T) and high respiratory rates (RRs). These extreme respiratory patterns affect drug delivery unpredictably through valved holding chambers (VHCs).

We compared in an in vitro study the effectiveness of two VHCs, one small (140 mL, Optichamber Diamond) and one large (350 mL, Babyhaler) without facemasks, to deliver salbutamol to filters positioned between the VHC mouthpieces and a breathing simulator. Different tidal volumes (from 30 mL to 200 mL) and RRs (25·min^-1 and 50·min^-1) were applied through a breathing simulator.

The amount of salbutamol delivered increased with increasing V_T in both VHCs for both RRs (ρ>0.87 and p<0.001 for both devices at both rates). The effect of RR was not as evident, but drug delivery tended to be higher at the higher rate. Drug delivery was significantly higher through the Optichamber Diamond as compared with the Babyhaler at every combination of RR and V_T up to a 12-fold difference.

We found marked differences in salbutamol delivery between the Babyhaler and Optichamber Diamond VHCs. The delivered dose of salbutamol increased with increasing V_T and RR with both VHCs but with differences related to valve dead spaces. Instead of considering all VHCs equal in clinical paediatric practice, each device should be tested in vitro with respiratory patterns relevant to small children with respiratory difficulties.

Children with respiratory problems are treated with inhaled drugs given via valved holding chambers (VHCs). Efficacy can vary up to 12-fold between devices. The effectiveness of VHCs should be tested in all age groups with different respiratory patterns.http://ow.ly/2Aca30mT2Pa

Lung deposition of 99mTc-radiolabeled albuterol delivered through a pressurized metered dose inhaler and spacer with facemask or mouthpiece in children with asthma

BACKGROUND

Research on the use of a pressurized metered dose inhaler (pMDI) with spacer (pMDI/spacer) in children has indicated oral inhalation via the spacer mouthpiece is more efficient than the combination of oral and nasal inhalation that occurs when a pMDI/spacer is used with a facemask. Changes in pMDI formulations and developments in spacer and facemask designs have highlighted the need for new comparative studies of spacer use, particularly focusing on the age at which children can be taught to transition from use of a pMDI/spacer with facemask to use of the spacer mouthpiece.

METHODS

Twelve children aged 3-5 years (7 males) with stable asthma were recruited. Of these, 10 children (6 males) completed both arms of the study. A transmission scan of each compliant subject was taken using a 37 MBq (99m)Tc flood source. Actuations (2-3) of a (99m)Tc-radiolabeled albuterol pMDI were administered through an antistatic spacer (OptiChamber Diamond) via either a facemask (medium LiteTouch facemask), or the spacer mouthpiece. The subject's inhalation pattern was simultaneously recorded using a pMDI Datalogger, and narrative data relating to tolerance and compliance were documented. Anterior and posterior planar scintigraphic scans were taken immediately after aerosol administration.

RESULTS

Mean (SD) lung deposition (% total dose) was 18.1 (9.1)% with the facemask and 22.5 (7.9)% with the spacer mouthpiece (p>0.05). Peripheral lung deposition (expressed as peripheral:central (P:C) ratio) was higher in 7 out of 10 children with the facemask compared with the spacer mouthpiece: 1.3 (0.26) vs. 1.2 (0.35); (p=0.11). Head and neck deposition was higher with use of the facemask compared with the spacer mouthpiece: 19.7 (10.6)% vs. 10.8 (5.3)% (p=0.011).

CONCLUSIONS

Lung deposition achieved using the spacer with facemask was higher than previously reported, with a difference of only 4.4% of total dose measured compared to the deposition with mouthpiece. This may be due to a combination of factors including pMDI formulation, and use of an antistatic spacer with a flexible, well-fitting facemask.

Product lifecycle approach to cascade impaction measurements

Over the lifecycle of an orally inhaled product (OIP), multi-stage cascade impactor (CI) measurements are used for different purposes and to address different questions. Full-resolution CIs can provide important information during product development and are widely used but are time- and resource-intensive, highly variable, and suboptimal for OIP quality control (QC) testing. By contrast, Efficient Data Analysis (EDA) combined with Abbreviated Impactor Measurement (AIM) systems pertinent either for QC and-possibly-for adult Human Respiratory Tract (pHRT) has been introduced for OIP performance assessment during and post-development. This article summarizes available evidence and discusses a strategy for using either abbreviated or full-resolution CI systems depending on the purpose of the measurement, such that adequate, accurate, and efficient testing of aerodynamic particle size distribution (APSD) of OIPs can be achieved throughout the lifecycle of a product. Under these proposals, a comprehensive testing program should initially be conducted by full-resolution CI in OIP development to ascertain the product's APSD. Subsequently, correlations should be established from the selected AIM CIs to the corresponding full-resolution system, ideally developing specifications common to both techniques. In the commercial phase, it should be possible to release product using AIM/EDA, keeping the full-resolution CI for investigations, change control, and trouble-shooting, thus optimizing resources for APSD characterization throughout the product lifecycle. If an in vitro-in vivo relationship is established and clinically relevant sizes are known, an AIM-pHRT could serve as a quick indicator that clinically relevant fractions have not changed and also, in the management of post-approval changes.