Effects of treatment cessation and re-treatment in randomized controlled trials of prucalopride in patients with chronic idiopathic constipation.

BACKGROUND: Prucalopride is a selective, high-affinity serotonin type 4 receptor agonist approved for the treatment of chronic idiopathic constipation (CIC) in adults. We investigated the impact of prucalopride cessation and re-treatment on efficacy and safety. METHODS: Data were from two randomized controlled trials in adults with CIC. In a dose-finding trial, complete spontaneous bowel movements (CSBMs) and treatment-emergent adverse events (TEAEs) were assessed during a 4-week run-out period after a 4-week treatment period (TP; prucalopride 0.5-4 mg once daily or placebo). In a re-treatment trial, CSBMs and TEAEs were assessed during two 4-week TPs (prucalopride 4 mg once daily or placebo) separated by a 2- or 4-week washout period. KEY RESULTS: In the dose-finding trial (N = 234; 43-48 patients/group), mean CSBMs/week and the proportion of responders (≥3 CSBMs/week) were higher with prucalopride than placebo during the TP, but similar in all groups 1-4 weeks after treatment cessation. TEAEs were less frequent following treatment cessation. In the re-treatment trial (efficacy analyses: prucalopride, n = 189; placebo, n = 205), the proportion of responders was similar in both TPs and significantly higher (p ≤ 0.001) with prucalopride (TP1, 38.6%; TP2, 36.0%) than placebo (TP1, 10.7%; TP2, 11.2%). Most patients who responded to prucalopride in TP1 responded again in TP2 (71.2%). TEAEs were less frequent in TP2 than TP1. CONCLUSIONS AND INFERENCES: Prucalopride cessation resulted in a loss of clinical effect to baseline levels within 7 days. Similar efficacy and safety were observed between TP1 and TP2 after prucalopride was re-initiated following a washout period.