The US Food and Drug Administration (FDA) has approved Linzess (linaclotide) as the first treatment for children living with irritable bowel syndrome with constipation (IBS-C), as the former blockbuster looks to grow its label.
Paediatric patients who are seven years and older with the chronic condition are now eligible to take the drug, which is co-marketed by Ironwood Pharmaceuticals and AbbVie. This adds another indication to the capsules that are already widely used by adults in the US for other forms of constipation.
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Ironwood, which heavily relies on Linzess sales for its bottom-line, saw shares rise to $2.06 at market close after the approval announcement by the FDA on 5 November, up 8.7% compared to market open. The US pharma company has a market cap of $334.6m.
Linzess, a guanylate cyclase-C (GC-C) agonist, was originally approved in 2012 to treat chronic idiopathic constipation and IBS-C in adults. The latest approval isn’t the first paediatric indication for the drug, with Linzess gaining approved to treat functional constipation in paediatric patients in June 2023.
The expansion to cover paediatric patients was based on a 12-week double-blind, randomised, parallel-group trial in paediatric patients aged seven to 17 years (NCT04026113). The primary endpoint was the proportion of patients who achieved at least a 30% reduction in abdominal pain and an increase of at least two spontaneous bowel movements per week from baseline for at least six weeks of the 12-week treatment period. The FDA said the efficacy results were consistent with results demonstrated in the adult IBS-C population. Also supporting the approval was the extrapolation of efficacy data in adults.
IBS-C is a common condition affecting children and adolescents, characterised by chronic constipation, abdominal pain, and bloating. There is no known underlying cause, with multiple factors – both genetic and environmental – contributing to the disorder. In paediatric patients, management typically includes lifestyle changes and over-the-counter medications.
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By GlobalDataLinzess sales, which are reported by AbbVie, reached $326m in Q3 2025, a 39% increase compared to the same period last year. Ironwood and AbbVie share US profits equally. Most of the drug’s sales come from the US market, with Constella – the treatment’s international brand name – generating just $11m.
However, Linzess used to be a big money maker for the two companies. The drug held blockbuster sales for three years between 2021 and 2023, with peak sales coming in at $1.1bn. While increasing prescription demand reflects growth, pricing erosion due to Medicare Part D redesign cut revenue.
Annual sales for Linzess are forecast to hover around the $650m mark in 2031, according to analysis by GlobalData’s Pharma Intelligence Center.
GlobalData is the parent company of Pharmaceutical Technology.
