A Study to Assess Adverse Events and Change in Disease Activity in Pediatric Participants (Age 6 Months to <2 Years) With Functional Constipation Who Are Treated With Linaclotide

Functional constipation (FC) is a common healthcare problem in children of all ages, potentially due to genetic predisposition, inadequate fiber and fluid intake, and immobility. Currently, there are no pharmacological therapies approved for the treatment of FC. This study will assess adverse events and change in disease activity with linaclotide therapy in participants with FC. Linaclotide is an approved drug being developed for the treatment of FC in pediatric patients who meet modified Rome IV criteria for childhood FC. In Part 1 of this study, participants are placed in 3 groups, which occur consecutively. Each group receives a different dosage of linaclotide. In Part 2 of the study, participants will be randomly assigned to receive either linaclotide or placebo. There is a 1 in 2 chance that participants will be assigned to placebo. Up to 30 and at least 18 pediatric participants 6 months to less than 2 years of age with FC will be enrolled in the study at approximately 38 sites worldwide. Participants will receive oral solution of linaclotide prepared from capsule by parent/guardian once daily for 4 weeks. There may be higher treatment burden for participants in this trial compared to their standard of care (due to study procedures). Participants will attend regular visits during the study at a hospital or clinic. The effect of the treatment will be checked by medical assessments, blood tests, checking for side effects and completing questionnaires.