Evaluation of the Safety of Lubiprostone in Pediatric Participants Aged ≥ 6 Years to < 18 Years With Functional Constipation

Inclusion Criteria: * Medically-confirmed diagnosis of Functional Constipation per Rome III Diagnostic Criteria for Childhood Functional Constipation * At least 6 years of age but less than 18 years of age at the time of randomisation * Only stable dose of selective serotonin re-uptake inhibitors (SSRIs), serotonin-specific reuptake inhibitor (SNRIs), or monoamine oxidase inhibitors (MAO) inhibitors are allowed if participant is taking antidepressants Exclusion Criteria: * Any gastrointestinal (GI) condition, other than constipation, affecting GI motility or defecation * Untreated faecal impaction at the time of screening * Medical/surgical condition that might interfere with the absorption, distribution, metabolism, or excretion of the study medication