The study is designed to assess if spinal cord injury patients have reduced pain after taking either pregabalin or placebo in a cross over design. Patients had either pain at the level of their injury or below the level of their injury.
This methodology study was terminated on October 13, 2008 based on interim results for an exploratory, novel endpoint. The results of the primary analysis at the interim for N=12 patients showed results that generally favored pregabalin but were not statistically significant compared to placebo. Based on the estimated conditional power, this result is unlikely to change with full recruitment of N=24 patients and therefore the data monitoring committee recommended termination of the trial. The decision to terminate the trial was not based on any safety concerns.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
DOUBLE
Enrollment
15
Pregabalin 150mg capsules BID for 7.5 days
Placebo capsules BID for 7.5 days
Pfizer Investigational Site
Randwick, New South Wales, Australia
Pfizer Investigational Site
St Leonards, New South Wales, Australia
Pfizer Investigational Site
Warrawong, New South Wales, Australia
Pfizer Investigational Site
Heidelberg, Victoria, Australia
Present Pain Intensity Score
Present pain intensity score: 0-10 numeric rating scale (NRS), 0 (no pain) to 10 (worst possible pain).
Time frame: Day 1: 0 (pre-dose), 0.5, 1, 2, 3, 4, 5, 6, 8, 10, and 12 hours (post-dose); Day 8: 0 (pre-dose), 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 24, 36, and 48 hours (post-dose)
Daily Pain Score
Daily Pain Score: Day 1 pain intensity over past 24 hours recorded on waking every morning. 0-10 numeric rating scale (NRS): 0 (no pain) to 10 (worst possible pain).
Time frame: Predose: Daily from 7 days before Visit 2 (start of Intervention 1) until the morning of Visit 5 (end of Intervention 2)
Dynamic Allodynia Area
Area of dynamic allodynia was assessed using a brush (SENSElab Brush 05; velocity approximately 20 millimeters per second \[mm/s\]) by stimulating along a pattern of 8 radial spokes. Stimulation was started from the non-painful perimetry. Subjects were asked to report change in sensation from non-painful to painful and the spot was marked onto the skin. The area of dynamic allodynia was determined from these 8 distances by calculating the area of an octagon (in centimeter squared \[cm2\]).
Time frame: Screening, Days 1 & 8: 0 (pre-dose) & 4 hours post-dose,
Dynamic Allodynia Pain Score
Five strokes (each approx. 6 centimeters \[cm\] long) were applied with a standardized brush (SENSELab Brush 05) across the painful site (and a control site) at a constant velocity (20 millimeters per second \[mm/sec\]). Pain in response to brush stimulation of the allodynic area was recorded using an 11-point numeric rating scale from 0 (no pain) to 10 (worst possible pain). Patients were asked to give a pain rating after each brush stroke. A painful sensation was considered as representing brush allodynia.
Time frame: Screening, Days 1 & 8: 0 (pre-dose), 0.5, 1, 2, 3, 4, 5, and 6 hours post-dose
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Punctate Allodynia Area
Area of punctate allodynia was determined using a von Frey filament (OptiHair2). Stimulation was started from the non-painful perimetry and repeated along a pattern of 8 radial spokes. With a movement along each spoke at steps of 5 millimeters (mm), the subjects reported sensation changes from non-painful to painful and the spot was marked on the skin. The area of punctate allodynia was determined from these 8 distances by calculating the area of an octagon (in square centimeter(s)\[cm2\]).
Time frame: Screening, Days 1 & 8: 0 (pre-dose) and 4 hours post-dose
Mechanical Pain Sensitivity Stimulus-Response Function
Mechanical pain sensitivity stimulus response function was assessed at the control and painful sites using calibrated von Frey monofilaments and the SENSElab brush. Seven different von Frey monofilaments (8 -512 milliNewtons \[mN\], force increases by a factor of two from filament to filament) and the brush were applied in a predetermined pseudo-random order. Pain rating for each stimulus: 11-point numeric rating scale (NRS) ranging from 0 (no pain) to 10 (worst possible pain).
Time frame: Screening, Days 1 & 8: 0 (pre-dose), & 2, 4, and 6 hours post-dose
Neuropathic Pain Symptom Inventory (NPSI)
NPSI: subject rated questionnaire to evaluate 5 dimensions of neuropathic pain (dimensions: burning \[superficial\] spontaneous pain, pressing \[deep\] spontaneous pain, paroxysmal pain, evoked pain, and paresthesia/dyesthesia). Includes 10 descriptors ranging from 0 (no symptoms) to 10 (worst symptoms imaginable) and 2 temporal items assessing duration of spontaneous ongoing and paroxysmal pain. Questionnaire generates a score in each relevant dimension. Total score is calculated as the sum of scores of the 10 descriptors, range: 0-100. Higher score indicates greater intensity of pain.
Time frame: Prior to morning dosing on Day 1 and prior to discharge on Day 8 for each period.
Pharmacokinetic Evaluations of Pregabalin
Pharmacokinetic (PK) results are not presented in this report due to early termination of the trial. Pregabalin PK was not measured as there was incomplete data to conduct pharmacokinetic/pharmacodynamic analyses.
Time frame: Day 1: 0 (pre-dose), 0.5, 1, 2, and 6 hours post-dose; Day 8: 0 (pre-dose), 1, 4, & 6 hours post-dose