3,4-diaminopyridine base effectively treats the weakness of Lambert-Eaton myasthenia

The Dapper Study Team

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16 Scopus citations


Introduction: 3,4-diaminopyridine has been used to treat Lambert-Eaton myasthenia (LEM) for 30 years despite the lack of conclusive evidence of efficacy. Methods: We conducted a randomized double-blind placebo-controlled withdrawal study in patients with LEM who had been on stable regimens of 3,4-diaminopyridine base (3,4-DAP) for ≥ 3 months. The primary efficacy endpoint was >30% deterioration in triple timed up-and-go (3TUG) times during tapered drug withdrawal. The secondary endpoint was self-assessment of LEM–related weakness (W-SAS). Results: Thirty-two participants were randomized to continuous 3,4-DAP or placebo groups. None of the 14 participants who received continuous 3,4-DAP had > 30% deterioration in 3TUG time versus 72% of the 18 who tapered to placebo (P < 0.0001). W-SAS similarly demonstrated an advantage for continuous treatment over placebo (P < 0.0001). Requirement for rescue and adverse events were more common in the placebo group. Discussion: This trial provides significant evidence of efficacy of 3,4-DAP in the maintenance of strength in LEM. Muscle Nerve 57: 561–568, 2018.

Original languageEnglish (US)
Pages (from-to)561-568
Number of pages8
JournalMuscle and Nerve
Issue number4
StatePublished - Apr 2018


  • 3,4-diaminopyridine
  • ELS
  • Eaton-Lambert syndrome
  • LEMS
  • LES
  • Lambert-Eaton myasthenia
  • Lambert-Eaton myasthenic syndrome
  • Lambert-Eaton syndrome
  • amifampridine
  • clinical trial
  • efficacy
  • timed up-and-go

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Physiology (medical)

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