Evaluation of Pregabalin in Idiopathic Small Fiber Neuropathy
Information source: University of Alberta
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Link to the current ClinicalTrials.gov record.
Condition(s) targeted: Small-Fiber Neuropathy
Intervention: Pregabalin (Drug); Placebo (Drug)
Sponsored by: University of Alberta
Official(s) and/or principal investigator(s):
Zaeem A Siddiqi, MD, PhD, Principal Investigator, Affiliation: MD, Profesor of Medicine, Neurology
Idiopathic Small Fiber Neuropathy (called SFN for short), is a condition where nerves that
sense pain have become damaged, and often painful. SFN pain is common, and it can affect
sleep, memory, health and overall quality of life.
Pregabalin is a drug commonly used to treat painful conditions, like nerve pain. It has been
available to doctors for many years, and many studies have been performed to evaluate its
effectiveness. In these studies, pregabalin has been shown to be very effective in the
treatment of nerve pain, with fewer side effects than many other medications currently
available. The purpose of
the study is to determine if pregabalin relieves pain more effectively than a pill
containing no medication (called a placebo). The study will also investigate any side
effects as well as the effectiveness and safety of the medication.
Official title: Evaluation of Pregabalin in Idiopathic Small Fiber Neuropathy
Study design: Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Investigator), Primary Purpose: Treatment
Primary outcome: To determine if there is any difference in the mean neuropathic pain score recorded in daily pain assessment scores between the pregabalin treatment phase (escalating twice daily dose of 75mg, 150mg) versus placebo treatment phase.
Secondary outcome: To determine if there is any difference in the mean scores of other quality of life measures of Change Scales between the pregabalin treatment phase (escalating twice daily dose of 75mg, 150mg) versus placebo treatment phase.
Painful small fiber sensory neuropathy (SFN) is relatively common and a disabling medical
condition. It is the most common type of painful sensory neuropathy in patients older than
50 years of age. It is defined as a neuropathy that exclusively or predominantly affects the
A-δ (small myelinated) and nociceptive C (unmyelinated) nerve fibers and their functions.
The neuropathic pain associated with SFN is described by the patients as burning ("feet are
on fire"), sharp ("knife-like, jabbing or pins and needles"), shooting, and aching pain in
the toes and feet. The feet are described as tingling, numb, or feeling tight, wooden or
dead. The pain is disabling and often exacerbated at night interfering and disrupting the
sleep pattern. Allodynia and cramps may also occur. Some patients also describe pressure
induced pain in their feet with standing and walking. The autonomic nerves may be involved
leading to increased or decreased sweating, facial flushing, skin discoloration and erectile
dysfunction in up to 40% of males. On examination there is a dramatic mismatch between the
symptoms and observable deficits in SFN. Only abnormal findings are the loss of pinprick and
temperature sensations in feet that may extend up to the knees. Touch sensation may be
diminished but other sensations are usually preserved. By definition, patients with SFN are
allowed to have minor involvement of large fibers distally with reduced vibration in toes
but the ankle reflexes are usually preserved.
This study will be of a crossover design thus minimizing the number of subjects needed. Each
patient will act as his/her own control. Previous studies of pregabalin have shown that the
desired effect is achieved by eight weeks of treatment. Therefore each patient will start on
either placebo or pregabalin. They will be assessed on this treatment arm for eight weeks.
There will be a two-week drug tapering and washout period before switching treatments,
followed by re-assessment for an additional eight weeks. This design minimizes the amount of
time that the patient will be treated with placebo.
Minimum age: 18 Years.
Maximum age: N/A.
- A diagnosis of idiopathic SFN (based on clinical and electrodiagnostic criteria).
- Each day for 7 days prior to Visit 2 (Washout) they must complete a modified
Quadruple Visual Analogue Scale₁ showing moderate to severe pain (i. e. a daily mean
rating score of ≥ 4).
- As the safety of pregabalin in pregnancy has not been established, females of
childbearing potential must have a negative βHCG serum and agree to practice
acceptable birth control methods.
- All subjects must have screening laboratory values that are within normal limits or
abnormal values that are deemed not clinically significant by the Principle
- Have a psychological or psychiatric condition that may hinder their ability to
provide important information
- History of psychosis, drug or alcohol abuse history within the last year
- Malignancy within the last 2 years (except skin cancer)
- Clinically significant conditions (including but not limited to cardiovascular or
hepatic diseases), and seizure disorders.
- Subjects with an abnormal 2-hour glucose tolerance test (i. e., glucose >7. 8 mmol/l)
will be excluded under "clinically significant conditions" as stated above.
- May not have participated in a previous trial of pregabalin, have a history of
intolerance or hypersensitivity to pregabalin.
- Patients with renal impairment (CrCl < 60 ml/min) will be excluded.
Locations and Contacts
University of Alberta Hospital, Edmonton, Alberta T6G-2B7, Canada
Starting date: October 2008
Last updated: September 9, 2010