The Food and Drug Administration has issued a Complete Response Letter (CRL) to United Therapeutics Corporation regarding the New Drug Application for Tyvaso DPI™ (inhaled treprostinil) for the treatment of pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with interstitial lung disease.

Tyvaso DPI is an investigational drug-device combination therapy that consists of a dry powder formulation of treprostinil and a small, portable, dry powder inhaler. In the CRL, the Agency cited a deficiency related to an open inspection issue at a third party facility that performs analytical testing of treprostinil.

“We are confident that the single deficiency identified in the complete response will be resolved quickly and that Tyvaso DPI can receive approval by the summer of 2022, if not earlier,” said Martine Rothblatt, PhD, Chairperson and Chief Executive Officer of United Therapeutics.

The NDA submission is supported by data from the open-label phase 1 BREEZE study ( Identifier: NCT03950739), which evaluated the safety and tolerability of Tyvaso DPI in 51 adult patients with PAH on a stable regimen of Tyvaso inhalation solution. Findings demonstrated that the transition from Tyvaso inhalation solution to Tyvaso DPI was safe and well tolerated.

In a separate pharmacokinetics study, results showed comparable systemic treprostinil exposure for each corresponding Tyvaso DPI and Tyvaso inhalation solution dose level.

If approved, Tyvaso DPI is expected to be a more convenient method of administration of treprostinil compared with nebulized Tyvaso therapy.


United Therapeutics Provides an Update on the Progress of the Tyvaso DPI™ New Drug Application. News release. October 18, 2021.