Studies of Dextromethorphan and Topiramate to Treat Oral and Facial Pain
Status:
Completed
Trial end date:
2002-01-01
Target enrollment:
Participant gender:
Summary
This study will evaluate the safety and effectiveness of two drugs-dextromethorphan and
topiramate-in treating orofacial (mouth and face) pain. Dextromethorphan, a commonly used
cough suppressant, and topiramate, an anti-seizure medicine, block certain receptors on brain
and spinal nerve cells that may cause the cells to produce electrical discharges and pain.
Patients 18 years of age and older with oral and facial pain with trigeminal nerve damage and
who have had pain daily for at least 3 months may be eligible for this study. Candidates will
be screened with a medical history, physical examination, blood tests and psychiatric
evaluation. These results will serve as baseline values for participants. Those enrolled in
the study will take either dextromethorphan or topiramate in a 2-part study as follows:
Dextromethorphan
In Part 1, patients will take dextromethorphan and lorazepam (a commonly used anti-anxiety
drug) separately in two 6-week periods. (Lorazepam is used in this study as an "active
placebo" for comparison with dextromethorphan. 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.) They
will take dextromethorphan for 4 weeks to determine the maximum tolerated dose (the highest
dose that does not cause troubling side effects) and will stay on that dose for the remaining
2 weeks. Then they will repeat this process with lorazepam. Patients who respond to either
drug may continue with Part 2 of the study, which compares these two drugs four more times to
confirm the response seen in Part 1. In Part 2, the maximum tolerated dose will be determined
in a 2-week period and that dose will be continued for another 2 weeks. This procedure will
be repeated eight times. Throughout the study, patients will keep a daily pain diary. They
will be contacted by telephone 2 to 3 times a week during dose escalation to check for side
effects. At the end of each of the two 6-week periods in Part 1 and at the end of each 4-week
period in Part 2 of the study, patients will have a 1-hour clinic visit. Participants who
live more than a few hours' drive from NIH will have a full telephone follow-up evaluation
instead of the clinic visits.
Topiramate
Patients who receive topiramate will follow a plan similar to that described above for
dextromethorphan, with the following exceptions. They will take topiramate and an inactive
placebo (a look-alike pill that has no active ingredients) in two separate 12-week periods.
Patients' maximum tolerated dose will be determined in the first 8 weeks and they will stay
on that dose for the remaining 4 weeks of each period. Patients who respond to the medication
in Part 1 may continue with Part 2 to confirm the response. Part 2 consists of six 6-week
periods. The first 4 weeks of each will be used to determine the maximum tolerated dose and
the patient will remain on that dose for the next 2 weeks. Patients will keep a daily pain
diary and will be contacted by phone 2 to 3 times a week while doses are being increased.
Patients who complete Part 2 of the topiramate study may participate in another phase of the
study that will last for 2 years. Those who continue for this phase will take topiramate for
the 2-year period. They will be followed regularly by a study nurse and will come to NIH
every 6 months for a follow-up visit.
Phase:
Phase 2
Details
Lead Sponsor:
National Institute of Dental and Craniofacial Research (NIDCR)