The U.S. Food and Drug Administration has delayed full approval of Liquidia Corp's treprostinil inhalation powder for pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with interstitial lung disease (PH-ILD). Instead, the FDA granted only tentative approval, which led to a nearly 37% drop in Liquidia's shares before market trading.

Liquidia announced that final approval of treprostinil inhalation powder cannot be obtained until May 23, 2025, when the regulatory exclusivity of United Therapeutics' Tyvaso DPI expires. The exclusivity covers the use of any dry-powder formulation of treprostinil for chronic treatment in both PAH and PH-ILD, a protection granted to Tyvaso DPI in May 2022.

Liquidia plans to challenge this exclusivity. The tentative approval marks another hurdle in the company’s efforts to bring treprostinil inhalation powder to market. Treprostinil inhalation powder was first granted tentative approval in 2021 for PAH but has been held from market due to a patent infringement dispute with United Therapeutics.

Both treprostinil inhalation powder and Tyvaso DPI are delivered through a compact, palm-sized device, offering a more convenient alternative to traditional nebulizers. The FDA's recent tentative approval of treprostinil inhalation powder for both PAH and PH-ILD follows an ongoing review of Liquidia’s marketing application initiated in January. PH-ILD encompasses a group of disorders characterized by lung scarring.