A pilot study assessing pharmacokinetics and tolerability of oral and intravenous baclofen in healthy adult volunteers

J Child Neurol. 2015 Jan;30(1):37-41. doi: 10.1177/0883073814535504. Epub 2014 Jul 14.

Abstract

Our objective was to characterize baclofen pharmacokinetics and safety given orally and intravenously. Twelve healthy subjects were enrolled in a randomized, open-label, crossover study and received single doses of baclofen: 3 or 5 mg given intravenously and 5 or 10 mg taken orally with a 48-hour washout. Blood samples for baclofen analysis were collected pre-dose and at regular intervals up to 24 hours post-dose. Clinical response was assessed by sedation scores, ataxia, and nystagmus. Mean absolute bioavailability of oral baclofen was 74%. Dose-adjusted areas under the curve between the oral and intravenous arms were statistically different (P = .0024), whereas area under the curve variability was similar (coefficient of variation: 18%-24%). Adverse effects were mild in severity and not related to either dose or route of administration. Three- and 5-mg intravenous doses of baclofen were well tolerated. Seventy-four percent oral bioavailability indicates that smaller doses of intravenous baclofen are needed to attain comparable total drug exposures.

Keywords: baclofen; baclofen withdrawal; intravenous therapy; muscle spasticity; pharmacokinetics.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Intravenous
  • Administration, Oral
  • Adult
  • Area Under Curve
  • Baclofen / blood*
  • Baclofen / pharmacokinetics*
  • Biological Availability
  • Cross-Sectional Studies
  • Dose-Response Relationship, Drug
  • Drug Tolerance
  • Electrocardiography
  • Female
  • Healthy Volunteers
  • Humans
  • Male
  • Muscle Relaxants, Central / blood*
  • Muscle Relaxants, Central / pharmacokinetics*
  • Pilot Projects
  • Time Factors

Substances

  • Muscle Relaxants, Central
  • Baclofen