US-based Ironwood Pharmaceuticals has started a Phase III clinical trial in the US evaluating once-daily linaclotide 72mcg capsule in adults suffering from chronic idiopathic constipation (CIC).
Currently, linaclotide is approved by the US Food and Drug Administration (FDA) as a 145mcg capsule to be taken once per day to treat adults with CIC and as a 290mcg capsule to be taken once per day in adults with irritable bowel syndrome with constipation (IBS-C).
Around 1,200 adult patients with CIC will be enrolled in the randomised, double-blind, placebo-controlled, multi-site Phase III clinical trial.
The company said that patients with CIC have fewer than three spontaneous bowel movements per week, and they also might experience recurrent straining, lumpy or hard stools and/or a sensation that their bowels are not fully empty.
During the trial, patients will be randomised to receive 145mcg of linaclotide once per day, 72mcg of linaclotide once per day, or placebo once per day for 12 weeks.
The trial's primary objective is to determine the efficacy and safety of linaclotide 72mcg in adult patients with CIC.
The primary efficacy evaluation is the percentage of patients who experience at least three complete spontaneous bowel movements (CSBMs) per week and an increase of at least one CSBM from baseline in the same week, and achieve both of these measures for nine out of 12 weeks.
Ironwood senior vice-president of clinical development Dr Michael Hall said: "The 72 mcg dose of linaclotide may provide physicians with more options that may enable them to better serve their adult chronic idiopathic constipation patients.
"The development of this additional dosage strength for linaclotide is part of our broader strategy to explore the ability of our pipeline of guanylate cyclase-C agonists to help millions of patients suffering from gastrointestinal dysfunction."
The Phase III trial of 72mcg linaclotide is being conducted jointly by Ironwood and Actavis, and the results are expected to be reported in 2016.
Actavis is Ironwood's co-development and co-promotion partner for linaclotide in the US.