Lubiprostone in Children With Functional Constipation

Dose administration details: * Participants with a body weight \<50 kg at baseline received Lubiprostone 12 mcg BID for 12 weeks. If the dose was safe but did not show any efficacy at Week 1, dosage was increased to 24 mcg BID. * Participants with a body weight \>50 kg at baseline received Lubiprostone 24 mcg BID for 12 weeks. If the dose was unsafe at Week 1, dosage was decreased to 12 mcg BID.