Clinically Relevant Test Methods to Establish <i>In Vitro</i> Equivalence for Spacers and Valved Holding Chambers Used with Pressurized Metered Dose Inhalers (pMDIs)
Bibliographic record
Abstract
Regulatory guidance in Canada and Europe recommends that the manufacturer of an inhaled drug product delivered by pressurized metered-dose inhaler (pMDI) identify a spacer (S) or valved holding chamber (VHC) to be used with their designated product. It therefore becomes necessary to include the S/VHC in the process of establishing bioequivalence (BE) to the reference pMDI product for both new-entry generic and subsequent market entry products (SMEPs). S/VHCs substantially modify the aerodynamic particle size distribution (APSD) of the inhaled medication, and potentially the spatial distribution of the mass of active pharmaceutical ingredient(s) [API(s)] depositing in the respiratory tract. The processes whereby S/VHCs can influence BE outcomes are examined, and the inadequacy of compendial in vitro methods to provide pertinent information to assess BE for the pMDI+VHC combination is highlighted. A three-part strategy is proposed whereby in vitro testing for BE can simulate more clinically-relevant conditions than in the current compendial procedures: 1. The inclusion of a short delay between inhaler actuation and sampling onset is appropriate when determining APSD at flow rate(s) suitable for the intended patient population; 2. Assessment of total emitted mass ex S/VHC by simulating tidal breathing pattern(s) appropriate for intended use; 3. Incorporation of appropriate face model(s), representative of the intended patient age range(s), into test procedures for S/VHCs with facemask, enabling clinically-appropriate dead space and fit-to-face to be simulated. Although the compendial authorities have been slow to recognize the need for such in vitro testing, a Canadian standard provides direction for implementing most proposals, which should result in better performance predictions and more appropriate clinical outcomes, highlighting similarities and differences between reference and test products.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.025 | 0.029 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.004 | 0.002 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.006 | 0.005 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".