Decreased Response to Botulinum Toxin Type A Agents Observed Over Time

Doctor preparing an injection
Preliminary findings showed the decrease in botulinum toxin type A therapeutic effect over time warrants further study.

The following article is part of conference coverage from the 2019 American Academy of Neurology Annual Meeting (AAN 2019) in Philadelphia, PA. Neurology Advisor’s staff will be reporting breaking news associated with research conducted by leading experts in neurology. Check back for the latest news from AAN 2019.

PHILADELPHIA — The therapeutic effect of botulinum toxin type A agents used to treat a variety of indications is shown to decrease over time, warranting future studies. This research was presented at the 2019 American Academy of Neurology Annual Meeting, held May 4-10, 2019, in Philadelphia, Pennsylvania.

The investigators of this retrospective study sought to assess the decreased therapeutic effect of botulinum toxin type A agents. Utilizing the FDA adverse event reporting system database, the investigators searched cases in which botulinum toxin type A was considered the “primary suspect” drug. The primary study outcome was the relative rate of decreased therapeutic effect reported as an adverse event, which was calculated by the presence of decreased therapeutic responses, or drug effect, divided by all incidents of adverse events.

A total of 12,280 cases using botulinum toxin type A agents were identified for a wide set of indications, from cosmetic to therapeutic. Adverse events reporting a decreased therapeutic response were present in 2.2% of incobotulinumtoxinA cases, 9.2% of abobotulinumtoxinA cases, and 11.6% of onabotulinumtoxinA cases. Comparing the relative incidence of decreased therapeutic effect over time in patients with >1 year vs <1 year of treatment for incobotulinumtoxinA was 0.0% vs 4.5%; for abobotulinumtoxinA was 11.9% vs 4.3%; and for onabotulinumtoxinA was 19.6% vs 10.1%.

Limitations to the study included the retrospective nature of the analysis, differing lengths of time since the products were approved, and variability in market share.

The investigators suggest that further studies are needed to understand the decrease in therapeutic effect over time associated with botulinum toxin type A agents.

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Kazerooni R. Decrease in therapeutic effect among botulinum toxin type A agents: analysis of the FDA adverse event reporting system database. Presented at: 2019 American Academy of Neurology Annual Meeting; May 4-10, 2019; Philadelphia, PA. Abstract P3.9-059.

This article originally appeared on Neurology Advisor