Algernon Pharmaceuticals has unveiled plans to commence a Phase IIb clinical study of NP-120 (Ifenprodil) to treat chronic cough in the third quarter of this year.

The double-blind, three-arm, placebo-controlled, randomised, multinational trial has been designed to assess NP-120 in approximately180 participants.

In the trial, all the participants will be randomised 1:1:1 to receive 20mg TID NP-120, or 40mg TID NP-120, or a placebo for 12 weeks.

Reduction in geometric mean 24-hour cough count over 12 weeks compared to the placebo is the study’s primary endpoint.

Tolerability, safety, and patient-reported quality-of-life measures will be some of the secondary endpoints of the trial.

The company stated that the plans to advance the Phase IIb study are based on positive data obtained from the Phase IIa study of Idiopathic Pulmonary Fibrosis (IPF) and chronic cough.

In the study, Ifenprodil demonstrated a significant improvement in mean objective 24-hour cough count, as well as waking cough counts, in patients after four and 12 weeks.

Algernon Pharmaceuticals CEO Christopher Moreau said: “The design of Phase II studies in chronic cough have been validated in trials conducted by Merck & Co and BELLUS Health.

“By mirroring the design of those studies, Algernon will have a direct benchmark for comparison and, if successful, a clear regulatory path for Ifenprodil for the treatment of chronic cough.”

Ifenprodil inhibits N-methyl-D-aspartate (NMDA) receptors selectively. These receptors comprise the NR2B subunit.

It can reduce neurons excitability and prevent the relaying of information along neuronal circuitry, including the cough reflex, by inhibiting NMDA receptors.

The company stated that ifenprodil can also inhibit the central and peripheral cough response neurons’ neuroplastic enhancement.