The FDA expanded approval of linaclotide (Linzess) for functional constipation to children aged 2 to 5 years, lowering the age threshold from 6 years. The decision was based on a phase 3 trial showing a significant improvement in spontaneous bowel movement frequency versus placebo.
The Food and Drug Administration expanded approval of linaclotide (Linzess) for functional constipation to children aged 2 to 5 years, Ironwood Pharmaceuticals said Wednesday, opening a new patient demographic for the blockbuster gastrointestinal drug.
"Managing functional constipation in young children is especially challenging, as this vulnerable patient population often continues to experience persistent symptoms despite treatment with over-the-counter therapies," Julie Khlevner, a pediatric gastroenterologist at Columbia University Vagelos College of Physicians and Surgeons, said in a statement. "The availability of an FDA-approved therapy with an established safety profile expands evidence-based treatment options."
The approval, granted priority review by the FDA, lowers the age threshold from 6 years to 2 years. Linzess was first cleared for pediatric functional constipation in children aged 6 and older in November 2025. The drug, a guanylate cyclase-C agonist taken as a 72-microgram capsule once daily, can be opened and mixed with applesauce or water for children unable to swallow capsules.
The decision was based on a 12-week phase 3 trial involving 123 patients aged 2 to 5 years who met modified Rome IV criteria for childhood functional constipation. Patients receiving linaclotide showed a mean increase of 2.1 spontaneous bowel movements per week from baseline, compared with 1.4 for placebo — a treatment difference of 0.7 (95 percent confidence interval, 0.03 to 1.31). Improvement was observed as early as week 1 and sustained through the 12-week period. The safety profile was consistent with prior studies in adults with chronic idiopathic constipation and older pediatric patients, with diarrhea as the most common adverse reaction.
The expanded label addresses a significant gap in pediatric care. Functional constipation in children is a chronic condition marked by hard, infrequent and often painful bowel movements, and no FDA-approved daily treatment existed for the 2-to-5 age group before this decision. Ironwood shares have risen 10.1 percent year to date, outperforming the industry's 6.5 percent decline.
Linzess is jointly developed and commercialized in the US by Ironwood and AbbVie. AbbVie reported first-quarter US net sales of $272.5 million for the drug, up 97 percent from a year earlier, and expects full-year 2026 US sales of $1.13 billion to $1.18 billion. Ironwood recorded $104.2 million as its share of net profit from US sales in the first quarter, up 169 percent. The drug is also approved for irritable bowel syndrome with constipation in adults and children aged 7 and older, and for chronic idiopathic constipation in adults.
The approval extends Linzess's commercial runway into a younger patient population with limited treatment options. Investors will watch prescription trends in the 2-to-5 age cohort over the coming quarters as a measure of adoption.
This article is for informational purposes only and does not constitute investment advice.
