Trial results comparing the effect of HFA-152a and HFA-134a propellants on mucociliary clearance were posted on ClinicalTrials.gov on 2026-04-14. The study, conducted in healthy participants, found that HFA-152a exhibited a geometric mean ratio of 0.9995 for mucociliary clearance compared to HFA-134a, suggesting similar effects on lung function.
Background
Asthma is a chronic respiratory condition affecting millions worldwide, often managed with inhaled medications delivered via metered-dose inhalers (MDIs). The propellants used in these inhalers play a crucial role in drug delivery. HFA-134a (1,1,1,2 - Tetrafluoroethane) is a widely used propellant, but there is ongoing research into alternative propellants like HFA-152a (1 - Difluoroethane) that may offer environmental or other benefits. Mucociliary clearance, the process by which the airways remove inhaled particles and pathogens, is a vital defense mechanism of the respiratory system. Assessing the impact of new propellants on this function is essential to ensure they do not adversely affect lung health.
Trial design
This completed Phase 1 study enrolled 24 healthy participants to assess the effect of HFA-134a (reference propellant) and HFA-152a (test propellant) on mucociliary clearance. Although the listed condition for the trial was Asthma, the study was specifically conducted in healthy adults to evaluate the propellants' direct impact on lung physiology. The primary objective was to compare mucociliary clearance after administration of each propellant, measured by the retention of nebulized 99mTechnetium (99mTc) radiolabeled particles.
Key results
The study evaluated mucociliary clearance through several measurements:
- Area Under the Percent Radiolabeled Particle Retention-time Curve up to 4 Hours [AUC(0-4h)] After Nebulized 99mTechnetium (99mTc) Inhalation on Day 7:
- For the HFA-152a group, the geometric least squares mean was 351.57 Hour*percentage (%).
- For the HFA-134a group, the geometric least squares mean was 351.76 Hour*percentage (%).
- Percentage of Radiolabeled Particle Retention at 1 Hour After Nebulized 99mTechnetium (99mTc) Inhalation on Day 7:
- The least squares mean for HFA-152a was 91.25 % of radiolabeled particle retention.
- The least squares mean for HFA-134a was 91.20 % of radiolabeled particle retention.
- Percentage of Radiolabeled Particle Retention at 1.5 Hours After Nebulized 99mTechnetium (99mTc) Inhalation on Day 7:
- The least squares mean for HFA-152a was 89.34 % of radiolabeled particle retention.
- The least squares mean for HFA-134a was 89.30 % of radiolabeled particle retention.
- Percentage of Radiolabeled Particle Retention at 3 Hours After Nebulized 99mTechnetium (99mTc) Inhalation on Day 7:
- The least squares mean for HFA-152a was 84.84 % of radiolabeled particle retention.
- The least squares mean for HFA-134a was 85.02 % of radiolabeled particle retention.
Key analyses further supported these findings:
- The Geometric Mean Ratio for AUC(0-4h) was 0.9995, with a 90.0% Confidence Interval of 0.9915 to 1.0075.
- The Mean Difference (Final Values) for 1-hour retention was 0.0513, with a 90.0% Confidence Interval of -0.6916 to 0.7941.
- The Mean Difference (Final Values) for 1.5-hour retention was 0.039, with a 90.0% Confidence Interval of -0.8175 to 0.8955.
- The Mean Difference (Final Values) for 3-hour retention was -0.1765, with a 90.0% Confidence Interval of -1.088 to 0.735.
Regarding safety, 9 participants in the HFA-152a group experienced adverse events (AEs), compared to 7 participants in the HFA-134a group. There were 0 serious adverse events (SAEs) reported in either group.
What this means
The results indicate that the HFA-152a propellant has a comparable effect on mucociliary clearance to the currently used HFA-134a propellant. The geometric mean ratio for AUC(0-4h) being very close to 1, and the narrow confidence interval encompassing 1, suggests that HFA-152a is functionally similar to HFA-134a in this critical lung defense mechanism. Similarly, the mean differences for particle retention at various time points were close to 0, with confidence intervals that include 0, further reinforcing the comparable effects. This finding is significant for the development of new inhaler formulations, particularly for conditions like Asthma, as it suggests HFA-152a could be a suitable alternative propellant without negatively impacting mucociliary function. The safety profile observed in this small Phase 1 study also appears similar between the two propellants, with no serious adverse events reported for either.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT06506266, titled "Study of the Effect of HFA-152a and HFA-134a Propellants on Mucociliary Clearance in Healthy Participants", were posted on 2026-04-14 on clinicaltrials.gov.