Safety, Tolerability, and Pharmacokinetics of Treprostinil Palmitil Inhalation Powder for Pulmonary Hypertension: A Phase 1, Randomized, Double-Blind, Single- and Multiple-Dose Study

Introduction Treprostinil is a prostacyclin vasodilator widely used for the treatment of pulmonary arterial hypertension (PAH) and, in its inhaled form, for pulmonary hypertension associated with interstitial lung disease (PH-ILD). Treprostinil palmitil inhalation powder (TPIP) is a dry powder formulation of treprostinil palmitil (TP), an ester prodrug of treprostinil. TPIP is designed to provide sustained release of treprostinil in the lung over a prolonged period, potentially enabling a once-daily (QD) dosing regimen and significantly higher tolerated doses compared with currently available treprostinil formulations. This phase 1 study assessed the safety, tolerability, and pharmacokinetics of TP and treprostinil following single and multiple QD administrations of TPIP in healthy volunteers. Methods Healthy adults (aged 18–45 years) were randomized to receive single or multiple QD inhalation doses of TPIP. Participants in the single-dose phase received TPIP 112.5, 225, 450, or 675 µg ( n = 6/dose) or placebo ( n = 2). Participants in the multiple-dose phase received TPIP 225 µg QD for 7 days ( n = 6), 112.5 µg QD for 4 days followed by 225 µg QD for 3 days ( n = 6), or placebo for 7 days ( n = 4). Results Overall, 41 of 42 participants (97.6%) completed the study. In the single-dose phase, 70.8% ( n = 17/24) of TPIP-treated participants experienced a treatment-emergent adverse event (TEAE) vs 0% ( n = 0/2) of placebo-treated participants; the most common TEAEs (≥ 20%) were cough (45.8%), dizziness (29.2%), and throat irritation (20.8%). In the multiple-dose phase, 83.3% ( n = 10/12) of TPIP-treated participants experienced a TEAE vs 50.0% of placebo-treated participants ( n = 2/4); the most common TEAEs were cough (58.3% TPIP vs 50.0% placebo), headache (50.0% vs 0%), nausea (33.3% vs 0%), chest discomfort (33.3% vs 0%), and dizziness (25.0% vs 0%). Most TEAEs were mild; only seven patients experienced a moderate TEAE, and no severe or serious TEAEs occurred. In the multiple-dose phase, participants whose doses were titrated from TPIP 112.5 µg QD to 225 µg QD experienced fewer TEAEs than those who received 225 µg QD at treatment initiation (66.7% vs 100.0%), and all TEAEs with dose titration were mild. After a single dose of TPIP, treprostinil elimination t 1/2 was 8.67–11.6 h and exposure was dose proportional, with mean (CV%) C max 78.4–717 pg/mL (38.6–72.9%) and AUC 0−∞ 1090–5480 pg·h/mL (11.5–30.0%). At steady state (TPIP 225 µg), the mean (CV%) of C max , C min , and AUC τ were 193–228 pg/mL (32.9–46.4%), 17.6–22.8 ng/mL (43.7–64.4%), and 1680–1820 pg·h/mL (28.7–36.6%), respectively. The elimination t 1/2 was 6.84–8.82 h after repeat dosing. No steady-state accumulation was observed. Plasma concentrations of TP were below the limit of quantification (100 pg/mL) at all time points measured. Conclusion TPIP was well tolerated at the doses tested, and dose titration improved tolerability. Treprostinil pharmacokinetics were linear and supportive of a QD treatment regimen. These results support further development of TPIP in patients with PAH and PH-ILD.