What is the median lethal dose (LD50) of botulinum toxin?

Updated: Mar 11, 2019
  • Author: Heather Rachel Davids, MD; Chief Editor: Elizabeth A Moberg-Wolff, MD  more...
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Botulinum toxin's median lethal dose (LD50) has been determined across several animal species but not in humans. A unit of BoNT-A usually is defined in terms of its biologic potency. One mouse unit (MU) of BoNT-A equals the LD50 for a 20-g Swiss-Webster mouse. Yet BoNT-A sensitivity varies among different species. LD50 in monkeys has been determined as 39 U/kg. Based on these findings from primate studies, human LD50 is estimated at approximately 3000 U for a 70-kg adult. Typical doses for larger muscle groups range from 60-400 total units given in a single treatment; however, because of inadequate understanding of the complete dose response curve in humans, a relative ceiling dose of 360 U, given no sooner than 12 weeks apart, is recommended.

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