It is an analog of trequinsin and, like trequinsin, is a highly selective inhibitor of the phosphodiesterase enzyme, PDE3; indeed, it is >3000-times more potent against PDE3 than PDE4.[2] As of October 2015, inhaled RPL-554 delivered via a nebulizer was in development for COPD and had been studied in asthma.[3]
Ensifentrine is indicated for the maintenance treatment of chronic obstructive pulmonary disease in adults.[1]
History
Ensifentrine was part of a family of compounds invented by Sir David Jack, former head of R&D for GlaxoSmithKline, and Alexander Oxford, a medicinal chemist; the patents on their work were assigned to Vernalis plc.[5][6][7]: 19–20
In 2005, Rhinopharma Ltd, acquired the rights to the intellectual property from Vernalis.[7]: 19–20 Rhinopharma was a startup founded in Vancouver, Canada in 2004 by Michael Walker, Clive Page, and David Saint, to discover and develop drugs for chronic respiratory diseases,[7]: 16 and intended to develop ensifentrine, delivered with an inhaler, first for allergic rhinitis, then asthma, then for COPD.[7]: 16–17 Ensifentrine was synthesized at a contract research organization, under the supervision of Oxford, and was studied in collaboration with Page's lab at King’s College, London.[2] In 2006 Rhinopharma recapitalized and was renamed Verona Pharma plc.[7]
Ensifentrine was approved for medical use in the United States in June 2024.[1][8]