Transitioning from treprostinil inhalation solution to treprostinil inhalation powder (TreT) is safe and well-tolerated in patients with pulmonary arterial hypertension (PAH), according to the results of a phase 1 clinical trial. The transition was accompanied by statistically significant improvements in key clinical assessments and patient-reported outcomes, leading to comparable systemic exposure between the 2 drug formulations.

The trial, called BREEZE, was an open-label, single-sequence study in which PAH patients already taking a stable dose of treprostinil inhalation solution switched to a corresponding dose of TreT.

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The trial enrolled 51 patients aged 18 and older at sites across the United States. The primary outcome measure of the trial was the number of patients with treatment-emergent adverse events. Secondary outcome measures included the plasma concentration of treprostinil, the change in 6-minute walk distance from baseline at week 3, patient satisfaction with and preference for inhaled treprostinil devices, and patient-reported PAH symptoms and their impact.

Forty-nine patients completed the 3-week treatment phase. The results showed adverse events were consistent with those in studies of inhaled treprostinil in patients with PAH. There were no drug-related serious adverse events. There were significant improvements in the 6-minute walk distance, Preference Questionnaire for Inhaled Treprostinil Devices, and PAH Symptoms and Impact questionnaire.

All patients who completed the treatment phase chose to participate in an optional extension phase of the study.

“The results of this study indicate that prostacyclin in a convenient, tolerable formulation may increase its accessibility to more patients earlier in the course of their disease, thereby potentially improving long-term outcomes,” the researchers concluded. 

Treprostinil is a chemically stable, long-acting prostacyclin analog initially approved as a parenteral formulation for the treatment of PAH. A treprostinil inhalation solution was approved for the treatment of the disease in 2009.


Spikes LA, Bajwa AA, Burger CD, et al. BREEZE: open-label clinical study to evaluate the safety and tolerability of treprostinil inhalation powder as Tyvaso DPI™ in patients with pulmonary arterial hypertension. Pulm Circ. Published online March 23, 2022. doi:10.1002/pul2.12063 

Open-label, clinical study to evaluate the safety and tolerability of TreT in subjects with PAH currently using Tyvaso (BREEZE). May 15, 2019. Updated March 30, 2021. Accessed March 31, 2022.