Abstract
Objective: The aim of this study was to assess the botulinum toxin type A (BoNT-A) agents for decreased therapeutic effect.
Background: Published literature comparing BoNT-A agents for antibody formation, resistance, and loss of effect is lacking. IncobotulinumtoxinA is the only BoNT-A agent that has removed unnecessary proteins, leaving just the 150 kDa active component.
Design/Methods: The United States Food and Drug Administration (FDA) adverse event reporting system (FAERS) database was utilized. The analysis was conducted on data between March 2014 and September 2017. BoNT-A cases were included when it was considered the “Primary Suspect” drug. The primary outcome was relative incidence of decreased therapeutic effect, defined as presence of either ‘therapeutic response decreased’ and/or ‘drug effect decreased’ being reported as an adverse event, divided by all cases of adverse events. This relative rate methodology has been well described previously in the pharmacovigilance literature and should not be confused with true incidence rate.
Results: A total of 12,280 BoNT-A cases were included across a wide array of cosmetic and therapeutic indications. Presence of adverse events involving decreased therapeutic effect for incobotulinumtoxinA was 2.2% (15/689); for abobotulinumtoxinA was 9.2% (79/858); and for onabotulinumtoxinA was 11.6% (1,247/10,733). Relative incidence of decreased therapeutic effect for patients on >1 year of treatment versus <1 year for incobotulinumtoxinA was 0.0% (0/10) vs 4.5% (13/291); for abobotulinumtoxinA was 11.9% (36/302) vs 4.3% (11/257); and for onabotulinumtoxinA was 19.6% (504/2,577) vs 10.1% (539/5,350).
Conclusions: Based on these preliminary findings, the decrease in BoNT-A therapeutic effect over time warrants further study. Limitations include the inherent limitations of retrospective analyses with pharmacovigilance databases, different lengths of time since product approvals, and variability in market share.
Disclosure: Dr. Kazerooni has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Merz North America.
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