Efficacy and safety of 5-Hydroxytryptophan on levodopa-induced motor complications in Parkinson's disease: A preliminary finding

J Neurol Sci. 2020 Aug 15:415:116869. doi: 10.1016/j.jns.2020.116869. Epub 2020 Apr 29.

Abstract

Background and purpose: Several studies have indicated that altered serotonergic neurotransmission may contribute to the motor features commonly associated with Parkinson's disease (PD) drug treatment such as levodopa-induced dyskinesias (LIDs). 5-Hydroxytryptophan (5-HTP) is the immediate precursor of serotonin. We have recently demonstrated that 5-HTP produces significant antidyskinetic effects in a rat model of PD. To date, there has been inconsistent research on the use of 5-HTP in PD. The purpose of this study was to compare the effects of 5-HTP versus placebo on levodopa-induced motor complications in PD patients.

Material and methods: A single-center, randomized, double-blind placebo-controlled cross-over study was performed. A total of 12 PD patients were diagnosed with LIDs and motor fluctuactions and subsequently were randomized to intervention; 11 subjects completed the entire 16-week protocol. Patients received placebo or 50 mg of 5-HTP daily in a cross-over design over a period of 4 weeks. For the assessment of efficacy on the motor functions and motor complications, the UPDRS (parts III and IV), Unified Dyskinesia Rating Scale (UDysRS), Wearing-Off Questionnaire (WOQ-19) and the self-reported 24-h home dyskinesia diaries were obtained at baseline and weeks 4, 8, 12 and 16 (T-end).

Results: Repeated measures analysis revealed a significant improvement of LIDs during the 50 mg 5-HTP treatment as assessed by the UDysRS and UPDRS-IV scores.

Conclusions: This study provides preliminary evidence of clinical benefit of 5-HTP against LIDs in PD. Larger studies with a longer treatment duration and a wider range of doses are warranted to corroborate these findings.

Keywords: 5-Hydroxytryptophan; Levodopa-induced dyskinesias; Motor fluctuactions; Parkinson's disease.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • 5-Hydroxytryptophan / therapeutic use
  • Animals
  • Antiparkinson Agents / adverse effects
  • Cross-Over Studies
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Dyskinesia, Drug-Induced* / drug therapy
  • Dyskinesia, Drug-Induced* / etiology
  • Humans
  • Levodopa / adverse effects
  • Parkinson Disease* / complications
  • Parkinson Disease* / drug therapy
  • Rats

Substances

  • Antiparkinson Agents
  • Levodopa
  • 5-Hydroxytryptophan