Octanoic acid in alcohol-responsive essential tremor: a randomized controlled study

Abstract

Objective: To assess safety and efficacy of an oral, single, low dose of octanoic acid (OA) in subjects with alcohol-responsive essential tremor (ET).

Methods: We conducted a double-blind, placebo-controlled, crossover, phase I/II clinical trial evaluating the effect of 4 mg/kg OA in 19 subjects with ET. The primary outcome was accelerometric postural tremor power of the dominant hand 80 minutes after administration. Secondary outcomes included digital spiral analysis, pharmacokinetic sampling, as well as safety measures.

Results: OA was safe and well tolerated. Nonserious adverse events were mild (Common Terminology Criteria for Adverse Events grade 1) and equally present after OA and placebo. At the primary outcome, OA effects were not different from placebo. Secondary outcome analyses of digital spiral analysis, comparison across the entire time course in weighted and nonweighted accelerometry, as well as nondominant hand tremor power did not show a benefit of OA over placebo. The analysis of individual time points showed that OA improved tremor at 300 minutes (dominant hand, F = 5.49, p = 0.032 vs placebo), with a maximum benefit at 180 minutes after OA (both hands, F = 6.1, p = 0.025).

Conclusions: Although the effects of OA and placebo at the primary outcome were not different, secondary outcome measures suggest superiority of OA in reducing tremor at later time points, warranting further trials at higher dose levels.

Classification of evidence: This study provides Class I evidence that a single 4-mg/kg dose of OA is not effective in reducing postural tremor in patients with ET at a primary outcome of 80 minutes, but is effective for a secondary outcome after 180 minutes.

Figure 1. Study design

Study flow diagram including 3 visits and time plan for study interventions during the 3-day inpatient visit, during which treatment was administered. Time points in minutes. OA = octanoic acid; PICC = peripherally inserted central venous catheter; PK = pharmacokinetic sampling.

Figure 2. CONSORT 2010 flow diagram

Enrollment, treatment allocation, follow-up, and analysis. OA = octanoic acid.

Figure 3. Octanoic acid effect on tremor power up to 300 minutes after administration

Normalized tremor power of postural hand tremor at the spectral tremor frequency peak, measured with weighted accelerometry, across time points up to 300 minutes after administration, shown (A) for the dominant hand and (B) both hands. Because individual time-point data were not normally distributed, plot shows median and interquartile range. X-axes represent normalized tremor power (baseline = 1); values >1 represent larger tremor power, <1 reduction in tremor power; *time points with significant differences between octanoic acid and placebo (p < 0.05).