Objective: To assess safety, therapeutic response and long-term benefit of higher dose Onabotulinum toxin A (OnaA).

Background: Botulinum toxin therapy is a powerful tool for treating many neurologic disorders. The US FDA-approved maximum OnaA dose is 400 units (U) per visit. While in practice higher doses are commonly used, safety and long-term benefit are not well reported. We hypothesize that >400U OnaA doses are well-tolerated, effective and of enduring benefit.

Method: We used the prospective University of Florida INFORM database and chart review to identify patients treated with OnaA above 400U/visit. We collected demographics, OnaA dose, body regions injected, patient-reported efficacy via 7-point Clinical Global Impression Scale (CGIS) and duration of benefit. Safety was determined by reported side effects at first follow-up from >400U visit. We assessed longer-term outcomes at 6 months, 12 months and last follow-up.

Results: We identified 68 patients [43 female (63%); mean age 60yo (range 24-87)] who received OnaA above 400U/session. At first visit >400U, mean total dose was 501U (range 425-800). 43 patients were injected for dystonia; 6 had blepharospasm, 31 cervical, 2 truncal, 14 upper limb and 14 lower limb dystonia (20 had >1 region injected). 25 patients were injected for spasticity; 18 upper limb, 16 lower (9 had both). At first follow-up, 47 patients (69%) reported overall good benefit by CGIS (17 rated “very much improved”, 30 “much improved”), while 14 rated “minimally improved”, 2 “no change” and 1 “minimally worse”. Mean duration of benefit was 9 weeks (SD 3). More than 70% of patients self-reported “very much improved” or “much improved” at 6 month, 1 year and last visit. No patient reported “much or very much worse” at any time. Ten patients (15%) reported adverse effects (AEs) at first follow-up, of which 3 had more than 1 AE [weakness (n=3), head drop (n=3), bruising (n=3), dysphagia (n=2)]. At last visit, 9 patients decreased dose below 400U due to: lack of benefit (n=2), AEs (n=2), fewer indications treated (n=2), benefit from interval deep brain stimulation (n=2) and insurance barrier (n=1). 36 patients discontinued injections at our center; reasons included lost to follow-up/moved (n=19), death/hospice (n=7), and least commonly, AEs (n=1).

Conclusion: The majority of patients tolerated >400U OnaA with continued benefit. OnaA doses greater than 400U may be safe and effective in appropriate patients.

« Back to 2019 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/high-dose-botulinum-toxin-therapy-safety-benefit-and-endurance-of-efficacy/