An open-label study demonstrated that the rapid transition from inhaled iloprost to Tyvaso® (treprostinil) was well tolerated and associated with maintenance of exercise capacity and improved quality of life in pulmonary arterial hypertension (PAH) patients. Tyvaso, manufactured by United Therapeutics Corp, Silver Spring, Md, is FDA approved for the treatment of PAH (WHO Group 1) to improve exercise ability. The findings were presented at the 2011 International Society of Heart & Lung Transplantation Annual Meeting in San Diego.
Tyvaso and inhaled iloprost are synthetic forms of prostacyclin (known as prostacyclin analogues), a molecule normally produced by the body but decreased in patients with PAH. The delivery of inhaled iloprost requires inhalation 6 to 9 times per day. Tyvaso is inhaled 4 times per day. The investigators hypothesized that Tyvaso might offer a reasonable administration option while maintaining the clinical benefit of prostacyclin.
A total of 73 patients (57 females and 16 males) enrolled at 13 medical institutions, took part in the study, which assessed the safety of transition, dosing, and effect on exercise capacity and quality of life. Participants initiated Tyvaso at three breaths (6 µg/breath) 4 times per day after immediate termination of inhaled iloprost. Dosing was escalated as tolerated to a target dose of nine breaths 4 times per day.
At week 12 following transition, 74% of subjects were administering at least nine breaths 4 times daily of Tyvaso and reached nine breaths in a mean of 18 days. The participants 6-minute walk test improved by a median of 16 meters (p<0.001; mean=16m; SD=36m). In addition, participants demonstrated statistically significant improvement at week 12 (p<0.001) in all domains of the Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR) used to evaluate overall quality of life, symptoms, and functioning. Total daily inhalation time decreased from 66 minutes to 13 minutes (p<0.001). Common adverse events included cough (74%), headache (44%), and nausea (30%). According to the researchers, no subject acutely deteriorated after transitioning.
“Inhaled prostanoids are an important part of the therapy for PAH,” said Robert Bourge, MD, a cardiologist at the University of Alabama at Birmingham, who presented the findings. “Early use was limited by problems with patient compliance due to the extremely rigorous regimen required for adequate dosing. This study shows that inhaled treprostinil was well tolerated and to our surprise, patients who were otherwise stable and transitioned from iloprost to inhaled treprostinil also had an improvement in a variety of endpoints after this therapeutic switch.”
Source: United Therapeutics Corp