Flexible dosing with fesoterodine 4 and 8 mg: a systematic review of data from clinical trials

To systematically review dose-escalation data from flexible-dose studies of fesoterodine and summarise factors associated with dose-escalation decisions.

A PubMed search was conducted using the terms (fesoterodine AND flexible dose), with no limits. Articles were included if they contained fesoterodine dose-escalation data for efficacy or safety outcomes or factors associated with dose-escalation decisions.

Of 13 articles identified by the search, 10 articles (six clinical studies) met inclusion criteria. In flexible-dose trials of fesoterodine, 51-63% of subjects initially receiving fesoterodine 4 mg opted for dose escalation to fesoterodine 8 mg. Escalators generally reported significantly more severe overactive bladder (OAB) symptoms, greater OAB symptom bother and worse health-related quality of life at baseline than non-escalators. Escalators demonstrated less treatment benefit with fesoterodine 4 mg than non-escalators. Non-escalators generally had a higher rate of dry mouth and constipation with fesoterodine 4 mg than escalators. The decision to escalate appeared to be determined by the efficacy/tolerability responses; fesoterodine escalators demonstrated a lower sensitivity (less efficacy and fewer adverse events) before their decision to escalate. By study end (8-11 weeks after escalation decision), the efficacy and tolerability profiles were similar in escalators and non-escalators.

Data from flexible-dose studies provide strong evidence that fesoterodine provides treatment benefit to individual subjects with OAB because of its true dose-response effect. In clinical practice, it can be worthwhile to escalate to fesoterodine 8 mg in individual subjects who require additional efficacy benefit.