This study will test the effectiveness of topiramate to treat pain caused by lumbar
radiculopathy, or sciatica. Sciatica results from damage to the lumbar nerve roots, typically
causing back pain and sharp, shooting pain down one or both legs. Although sciatica is
common, there are no good treatments for it. Topiramate belongs to a group of medications
commonly used to treat pain caused by nerve damage.
Patients between 18 and 75 years of age who have had sciatica pain daily for at least 3
months may be eligible for this study. (This is taken from the first paragraph of the
Qualification Criteria in the consent form. The inclusion criteria on page 6 of the protocol
say "low back pain of 3 months duration or longer present at least 5 out of 7 days a week"
and signs and symptoms of lumbar radiculopathy. Which is correct?)
Participants will provide a medical history, as well as occupational and social information.
They will undergo a standard neurological examination, including a test of cognitive
(thinking) abilities, muscular function, reflexes and a sensory examination. The latter
involves testing with a pin placed on the surface of the skin. Participants will also have
routine blood tests and will fill out questionnaires on their daily functioning and
psychological well being. Additional procedures may include magnetic resonance imaging (MRI)
scans and possible referral to a psychiatrist for evaluation of depression or emotional
difficulties.
This "cross-over" study consists of two parts. In one part, patients will receive topiramate
and in the other, an active placebo. An active placebo is a drug that does not work for the
problem being studied but whose side effects are like those of the test drug. Diphenhydramine
(Benadryl) is the active placebo used in this study. Diphenhydramine is an allergy medication
with very mild side effects, such as drowsiness. During both parts of the study-topiramate
and placebo-patients will keep a daily log in which they rate their pain, record other
procedures they undergo, such as injections and manipulations, and record medication side
effects.
In the first week of the study, patients will remain on their current medications and record
pain levels once a day. After the first week, they will begin taking the study drugs-either
topiramate in increasing doses ranging from 50 to 400 mg. or diphenhydramine in doses ranging
from 6.25 to 50 mg. The drug doses will be increased gradually over 4 weeks to minimize
possible side effects. Increases will continue until the maximum tolerated dose is reached.
Patients will continue on the highest tolerated dose for two weeks and then be tapered off
gradually over 12 days. They will remain off drugs completely for a 2-day washout period and
then begin the next treatment. Those who took topiramate for the first part will take
diphenhydramine for the second part and vice versa.
A study nurse will call patients twice a week throughout the study to check for problems and
answer questions. A physician will see patients 6 weeks after the start of each treatment.
During the last visit, at the end of the study, patients will repeat the questionnaires they
filled out at the beginning of the study. Patients and their doctors will be informed of the
medications that were effective in each individual's care.
Phase:
Phase 2
Details
Lead Sponsor:
National Institute of Dental and Craniofacial Research (NIDCR)