The purpose of this study is characterize the efficacy, safety, tolerability, and steady-state plasma levels after once-daily oral dosing of prucalopride (R108512) as a solution, 0.01 mg/kg to 0.03 mg/kg, given to paediatric subjects with functional faecal retention (FFR) for 8 weeks.

Hypothesis:

Pharmacokinetic profile of prucalopride in paediatric subjects is expected to resemble the adult pharmacokinetic profile. Safety and tolerability profile are expected to resemble the adult profile.

This is a multicentre, open-label trial in which paediatric subjects (ages 4 to 12 years) with FFR were administered prucalopride in oral solution once daily for 8 weeks. Subjects who entered this extension trial had completed PRU-USA-12, a single-dose pharmacokinetic trial, usually within the previous week.

Evaluations for efficacy, safety and tolerability were performed, and plasma samples for analysis of prucalopride levels were obtained at 2, 4, 6 and 8 weeks.

The initial dosage of prucalopride oral solution was 0.02 mg/kg/day. Dependent on the subject's response, the parent could adjust the dosage within a range of 0.01 mg/kg/day to 0.03 mg/kg/day.

Inclusion Criteria:

• Subject completed the PRU-USA-12 pharmacokinetic trial
• Subject bowels had been "cleaned-out" (ie, any faecal impactions removed)
• Written informed consent, signed by the subject's legal guardian and by the investigator
• Subject assent documented in the form of a note-to-file in the subject's source documentation

Exclusion Criteria:

• No exclusion criteria