Algernon Pharmaceuticals reports results of study on ifenprodil

Algernon Pharmaceuticals reports that ifenprodil achieved a 93% reduction in median cough count in an acute guinea pig citric acid challenge study. The multi-dose study was conducted under the direction of Seyltx, a private US-based drug development company which recently acquired Algernon’s ifenprodil research program for the purchase price of $2M USD and a 20% equity position. The study was designed to inform dose selection in Seyltx’s planned Phase 2b ifenprodil human study, recently named SILINDA, in refractory chronic cough. Seyltx has also announced that patient enrollment in the study is expected to begin in early 2025. Ifenprodil is an N-methyl-D-aspartate receptor antagonist specifically targeting the NR2B subunit, which prevents glutamate signalling. Ifenprodil represents a first-in-class potential treatment for chronic cough and interferes with central signalling in the brain, supressing the urge to cough. The near-complete suppression of cough was observed in animals receiving a dose of 30 mg/kg, in a dose-dependent manner, below the no observed adverse effect level dose. Other dosing arms included 1, 3, and 10 mg/kg. A clear and statistically significant dose response was observed. The full results of the study will be presented at the London International Cough Symposium July 18th – 19th, 2024. In an earlier Algernon Phase 2a clinical trial measuring cough in patients with idiopathic pulmonary fibrosis, ifenprodil, 20 mg TID, reduced cough by ~40% from baseline.