Evaluation and Selection of the Inhaler Device for Treprostinil Palmitil Inhalation Powder

Treprostinil palmitil (TP) is a prodrug of treprostinil that has been formulated as an inhaled powder, termed TPIP, for evaluation in patients with pulmonary arterial hypertension. In these characterization studies we investigated the aerosol performance of TPIP in response to changes in capsule fill, device resistance, and inspiratory flow rate to enable selection of an inhaler for clinical use. Capsules containing 8, 16 or 32 mg of TPIP (80, 160, or 320 μg TP, respectively) were evaluated using four commercially-available, breath-actuated RS01 devices (Plastiape, S. p.A., Osnago, Italy) with low, medium, high or ultra-high inspiratory resistances, creating 12 different capsule and device configurations for evaluation. Aerosol characterization was performed using the next generation impactor at compendial conditions of 23°C and 35% relative humidity and a flow rate corresponding to a 4 kPa pressure drop. The aerosol mass median aerodynamic diameter, geometric standard deviation, fine particle fraction, emitted dose and fine particle dose (FPD) were calculated from the in vitro impactor data. The TP emitted dose at 4 kPa exceeded 75% for all 12 capsule and device configurations. The FPD, an estimate of the respirable dose, varied between 61.0 and 70.6% of the loaded TP dose for all four devices with the 8 and 16 mg TPIP capsule dose. For the 32 mg TPIP capsule dose, the FPD remained above 61.0% for the high and ultra-high resistance devices but decreased to 48.5 and 52.6% for the low and medium resistance devices, respectively. Based on this initial data, the high resistance device was selected for additional characterization studies at 40 and 80 L/min corresponding to pressure drops of 1.4 and 5.4 kPa. The FPD was relatively insensitive to changes in flow rate, providing an expectation of a consistent total lung dose of TP under scenarios simulating variability in how the device is used. Based on these findings, the high resistance device was chosen for further development in human clinical trials

Preclinical Investigation of a Lipoglycopeptide Dry Powder Inhalation Therapy for the Treatment of Pulmonary MRSA Infection

The increased prevalence of pulmonary methicillin-resistant Staphylococcus aureus (MRSA) infection in patients living with cystic fibrosis (CF) is concerning due to a correlation with reduced life expectancy and lack of available treatment options. RV94 is a next generation lipoglycopeptide designed for pulmonary delivery that preclinically demonstrated high potency against MRSA in planktonic and protected colonies and improved pulmonary clearance relative to same class molecules. Here, RV94 was formulated into a dry powder for inhalation (DPI) to investigate the localized treatment of pulmonary MRSA presented in a potentially more convenient dosage form. RV94 DPI was generated using a spray-drying process with 12.5 wt% trileucine and demonstrated aerosol characteristics (2.0 μm MMAD and 73% FPF) predictive of efficient pulmonary deposition. In vivo PK from a single dose of RV94 DPI delivered by inhalation to rats yielded lung levels (127 μg/g) much greater than the MRSA minimum inhibitory concentration (0.063 μg/mL), low systemic levels (0.1 μg/mL), and a lung t1/2 equal to 3.5 days. In a rat acute pulmonary MRSA model, a single dose of RV94 DPI delivered by inhalation either up to seven days prior to or 24 h after infection resulted in a statistically significant reduction in lung MRSA titer

Development and Characterization of Treprostinil Palmitil Inhalation Aerosol for the Investigational Treatment of Pulmonary Arterial Hypertension

Treprostinil palmitil (TP) is a prodrug of treprostinil (TRE), a pulmonary vasodilator that has been previously formulated for inhaled administration via a nebulizer. TP demonstrates a sustained presence in the lungs with reduced systemic exposure and prolonged inhibition of hypoxia-induced pulmonary vasoconstriction in vivo. Here, we report on re-formulation efforts to develop a more convenient solution-based metered-dose inhaler (MDI) formulation of TP, a treprostinil palmitil inhalation aerosol (TPIA) that matches the pharmacokinetic (PK) and efficacy profile of a nebulized TP formulation, treprostinil palmitil inhalation suspension (TPIS). MDI canisters were manufactured using a two-stage filling method. Aerosol performance, formulation solubility, and chemical stability assays were utilized for in vitro evaluation. For in vivo studies, TPIA formulations were delivered to rodents using an inhalation tower modified for MDI delivery. Using an iterative process involving evaluation of formulation performance in vitro (TP and excipient solubility, chemical stability, physical stability, and aerosol properties) and confirmatory testing in vivo (rat PK and efficacy, guinea pig cough), a promising formulation was identified. The optimized formulation, TPIA-W, demonstrates uniform in vitro drug delivery, a PK profile suitable for a once-daily administration, efficacy lasting at least 12 h in a hypoxic challenge model, and a significantly higher cough threshold than the parent drug treprostinil