The primary objective of this study is to characterize baclofen pharmacokinetics following oral and intravenous administration in patients who are on chronic oral baclofen therapy. The secondary objective is to determine the safety profile of an IV baclofen formulation. This study is a randomized crossover study with two treatment arms. All subjects will receive a dose of oral baclofen and a dose of IV baclofen on separate study days. Whether the oral or intravenous form is given on the first study day will be randomized in a 1:1 manner. The pharmacokinetic and tolerability information gained from this study will support the development of further studies to assess the use of IV baclofen to prevent or treat baclofen withdrawal syndrome.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
12
Each subject will receive one dose of oral baclofen and one dose of intravenous baclofen on different study days.
University of Minnesota
Minneapolis, Minnesota, United States
oral bioavailability
oral bioavailability is the fraction of an administered dose of unchanged drug that reaches the systemic circulation
Time frame: 5, 15, 30 minutes, and 1, 2, 4, 6, 8, 10, 12, and 24 hours after administration
Area Under the Curve From Time Zero to Extrapolated Infinite Time [AUC (0 - ∞)]
AUC (0 - ∞)= Area under the plasma concentration versus time curve (AUC) from time zero (pre-dose) to extrapolated infinite time (0 - ∞). It is obtained from AUC (0 - t) plus AUC (t - ∞).
Time frame: 5, 15, 30 min and 1, 2, 4, 6, 8, 10, 12, and 24 hours after administration
Plasma Decay Half-Life (t1/2)
Plasma decay half-life is the time measured for the plasma concentration to decrease by one half.
Time frame: 5, 15, 30 min and 1, 2, 4, 6, 8, 10, 12, and 24 hours after administration
Maximum concentration (Cmax)
The maximum concentration is the maximum baclofen concentration observed
Time frame: 5, 15, 30 min and 1, 2, 4, 6, 8, 10, 12, and 24 hours after administration
Tmax
Tmax is the time at which the maximum baclofen concentration was observed
Time frame: 5, 15, 30 min and 1, 2, 4, 6, 8, 10, 12, and 24 hours after administration
assessment of sedation
Sedation will be measured using the Stanford Sleepiness Scale.
Time frame: up to 12 hours
Ataxia
A rating scale of ataxia will be used: 0=none, 1=mild, 2=severe For those who are ambulatory, this will be assessed by gait. Ratings will be: mild-unsteady with tandem gait testing, but able to perform without assistance severe-unable to perform tandem gait testing without assistance. For non-ambulatory subjects, ataxia will be assessed by finger to nose and finger pursuit maneuvers.
Time frame: up to 12 hours after infusion
Nystagmus
Nystagmus will be measured using the following scale. 0=none, 1=mild, 2=severe mild-present on extreme gaze; severe-present on midline gaze
Time frame: up to 12 hours following drug administration
blood pressure
diastolic and systolic blood pressure will be measured
Time frame: 5 minutes immediately prior to, and during the IV infusion and oral administration, then every 15 minutes for 1 hour, then every hour for 12 hours.
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