An exploratory, placebo-controlled, dose-response study of the efficacy and safety of onabotulinumtoxinA in spinal cord injury patients with urinary incontinence due to neurogenic detrusor overactivity.

PURPOSE: To explore the dose response to onabotulinumtoxinA 50, 100, and 200 U in patients with spinal cord injury (SCI) with urinary incontinence (UI) due to neurogenic detrusor overactivity (NDO).

METHODS: Patients (N = 73) with SCI (level T1 or lower) with NDO and UI (≥14 UI episodes/week) received 30 intradetrusor injections of onabotulinumtoxinA (50 U [n = 19], 100 U [n = 21], or 200 U [n = 17]) or placebo (n = 16) via cystoscopy, avoiding the trigone. Changes from baseline in UI episodes/week, volume voided/micturition, maximum cystometric capacity, and maximum detrusor pressure (MDP) during first involuntary detrusor contraction (IDC) were evaluated. Adverse events (AEs) were assessed.

RESULTS: A significant linear dose response for UI episodes/week was identified at weeks 18, 30, 36, 42, and 54 (P < 0.05) with a similar trend (P = 0.092) at week 6 (primary time point). A significant linear dose response was observed in volume/void at all post-treatment time points up to week 54 (P < 0.05) and in MDP during first IDC at week 6 (P = 0.034). The proportion of patients who achieved continence at week 6 was highest in the 200 U group. Duration of effect was longest with the 200 U dose, compared with other treatment groups. The AEs were comparable across groups; urinary tract infection was the most common AE across all treatment groups.

CONCLUSIONS: In this exploratory dose-response study of SCI patients with UI due to NDO, onabotulinumtoxinA 200 U was the most effective dose. The AE profile was comparable across all groups.